Journal of Applied and Computational Mechanics
https://jacm.scu.ac.ir/
Journal of Applied and Computational Mechanicsendaily1Fri, 01 Oct 2021 00:00:00 +0330Fri, 01 Oct 2021 00:00:00 +0330Thermal Buckling Analysis of Circular Bilayer Graphene Sheets Resting on an Elastic Matrix Based on Nonlocal Continuum Mechanics
https://jacm.scu.ac.ir/article_14896.html
In this article, the thermal buckling behavior of orthotropic circular bilayer graphene sheets embedded in the Winkler&ndash;Pasternak elastic medium is scrutinized. Using the nonlocal elasticity theory, the bilayer graphene sheets are modeled as a nonlocal double&ndash;layered plate that contains small scale effects and van der Waals (vdW) interaction forces. The vdW interaction forces between the layers are simulated as a set of linear springs using the Lennard&ndash;Jones potential model. Using the principle of virtual work, the set of equilibrium equations are obtained based on the first-order shear deformation theory (FSDT) and nonlocal differential constitutive relation of Eringen. Differential quadrature method (DQM) is employed to solve the governing equations for simply-supported and clamped boundary conditions. Finally, the effects of the small scale parameter, vdW forces, aspect ratio, elastic foundation, and boundary conditions are considered in detail.Numerical Simulation of Unsteady Flow toward a Stretching/Shrinking Sheet in Porous Medium Filled with a Hybrid Nanofluid
https://jacm.scu.ac.ir/article_14641.html
The purpose of this study is to present simulation and numerical solutions to the unsteady flow and heat transfer near stagnation point over a stretching/shrinking sheet in porous medium filled with a hybrid nanofluid. Water (base fluid), nanoparticles of titania and copper were considered as a hybrid nanofluid. It is worth mentioning that evaluating the heat transfer enhancement due to the use of hybrid nanofluids has recently become the center of interest for many researchers. The coupled non-linear boundary-layer equations governing the flow and heat transfer are derived and reduced to a set of coupled non-dimensional equations using the appropriate transformations and then solved numerically as a nonlinear boundary value problem by bvp4c scheme from MATLAB. To validate the modeling of hybrid nanofluid and also numerical procedure, the value of the skin friction and the heat transfer rate for the limited cases of pure water, titania/water and copper/water is obtained and compared with previously reported results that demonstrate an excellent agreement. In the present investigation, the thermal characteristics of hybrid nanofluid are found to be higher in comparison to the base fluid and fluid containing single nanoparticles, respectively. It can be concluded that both skin friction coefficient and local Nusselt number enhance almost linearly with increasing the copper nanoparticle volume fraction (as second nanoparticle). Besides, the porosity and the magnetic effect amplify heat transfer rate, while the unsteadiness parameter has a reducing effect on heat transfer rate in problem conditions.Size-dependent Nonlinear Forced Vibration Analysis of Viscoelastic/Piezoelectric Nano-beam
https://jacm.scu.ac.ir/article_15269.html
In this paper, the nonlinear forced vibration of isotropic viscoelastic/ piezoelectric Euler-Bernoulli nano-beam is investigated. For this purpose, the consistent couple stress theory is utilized for modeling the viscoelastic/piezoelectric nano-beam. Hamilton&rsquo;s principle is also employed to obtain the governing equations of motion. Further, the Galerkin method is used in order to convert the governing partial differential equations to a nonlinear second-order ordinary differential one, and then multiple scale method is used to solve motion equation.Effects of Inclined Magnetic Field and Porous Medium on Peristaltic Flow of a Bingham Fluid with Heat Transfer
https://jacm.scu.ac.ir/article_15007.html
The current paper aims to explain the peristaltic mechanism of a Bingham fluid with varying viscosity. The fluid is considered to flow within a porous medium and subjected to a magnetic field with significant inclination. Heat transfer characteristics are studied with convective conditions and variable thermal conductivity. The solution is obtained by the perturbation technique, where small values of variable liquid properties are utilized. The graphs plotted indicate that variation in viscosity as well as thermal conductivity actively contribute to reduce the pressure gradient. Further, for a higher radius of the plug flow region, a higher pressure rise occurs. The magnetic parameter and Grashof number influence the trapping phenomenon by reducing the dimensions of the bolus.Heat Transfer of Hybrid-nanofluids Flow Past a Permeable Flat Surface with Different Volume Fractions
https://jacm.scu.ac.ir/article_14842.html
Nowadays, the preparation, characterization, and modeling of nanofluids are deliberated in plenty to improve the heat transfer effects. Therefore, this paper centers on the heat transfer effects of three separate hybrid nanoparticles such as Al2O3-SiO2, Al2O3-TiO2, and TiO2-SiO2 with a base fluid such as water to gratify the advances. Analytical investigations for the Marangoni convection of different hybrid nanofluids over the flat surface for the cases such as suction, injection and impermeable were analyzed. A validation table for the comparison between analytical and numerical studies is tabulated. The influence of the hybrid nanoparticles solid volume fraction and the wall mass transfer parameter are mentioned through graphs at the side of the heat transfer rate tabulation. The impact of solid volume fraction decelerates the velocity distribution and raises the temperature distribution for all the three hybrid nanofluids in the cases of suction, impermeable, and injection. While relating the surface velocity and heat transfer rate of the three hybrid nanofluids, Al2O3-SiO2/water has a higher surface velocity, TiO2-SiO2/water has a higher heat transfer rate and Al2O3-TiO2/water has lower surface velocity and heat transfer rate for the increment of wall mass transfer parameter.Nanostructure, Molecular Dynamics Simulation and Mechanical Performance of PCL Membranes Reinforced with Antibacterial Nanoparticles
https://jacm.scu.ac.ir/article_15466.html
Recently, the application of porous bio-nanocomposites has been considered by many researchers for orthopedic application. Since experimental tests for obtaining the mechanical and physical properties of these nanostructured biomaterials are very expensive and time-consuming, it is highly recommended to model and simulate these bio-nanoscale materials to predict their mechanical and physical properties. In this study, three-phase porous bio-nanocomposite membranes were fabricated with Titanium oxide (TiO2), Hydroxyapatite (HA) and Polycaprolactone (PCL) polymer. HA and TiO2 are both biocompatible and biodegradable. The samples were fabricated with various amounts of titanium oxide and the materials characterization has been performed on selected sample. The molecular dynamics technique (MD) have been used to predict the mechanical performance of the nanocomposite models. The MD simulations were performed for single phase material and the developed for two phases equivalent components as a new approach in using MD simulation results. The results indicated the close relationship between the experimental data and simulation values for the selected sample. Moreover, phase and morphology of these nanostructures have been investigated using SEM results. Therefore, based on the proposed approach, MD simulation can be applicable for predicting the properties of porous bio-nanocomposite membrane.Topology Optimization of Laminated Composite Plates and Shells using Optimality Criteria
https://jacm.scu.ac.ir/article_14895.html
Laminated composite materials have the advantage of desired properties and are vastly replacing the existing traditional materials in Civil Engineering construction. In the present study, it is aimed to extend the study on the analysis of laminated composites plates and shells towards structural optimization. Topology optimization is performed using two different objective functions namely strain energy and fundamental frequency. The results of optimization have shown clearly that the distribution of material is dependent on the laminae. The optimal arrangement of material is obtained after using a cut-off relative density. It is confirmed to be a well-connected grid and is examined in detail. The results have shown that the optimal arrangement of material for a simply supported plate carrying a uniformly distributed load is at the centre of the edges and not towards the corners, Hence, the optimal arrangement of beams using strain energy is to align by joining the centre of the edges similar to plus (+) sign.Numerical Solution of Time Fractional Cable Equation via the Sinc-Bernoulli Collocation Method
https://jacm.scu.ac.ir/article_15318.html
An important equation usually used in modeling neuronal dynamics is cable equation. In this work, a numerical method for the fractional cable equation which involves two Riemann-Liouville fractional derivatives is proposed. Our computational technique is based on collocation idea where a combination of Bernoulli polynomials and Sinc functions are used to approximate the solution to this problem. The constructed approximation by our method convert the fractional cable equation into a set of algebraic equations. Also, we provide two numerical examples to confirm the accuracy and effectiveness of the present method.A Note on the Hydromagnetic Blasius Flow with Variable Thermal Conductivity
https://jacm.scu.ac.ir/article_15467.html
In this paper, the influence of the transverse magnetic field is unraveled on the development of steady flow regime for an incompressible fluid in the boundary layer limit of a semi-infinite vertical plate. The sensitivity of real fluids to changes in temperature suggests a variable thermal conductivity modeling approach. Using appropriate similarity variables, solutions to the governing nonlinear partial differential equations are obtained by numerical integration. The approach used here is based on using the shooting method together with the Runge-Kutta-Fehlberg integration scheme. Representative velocity and temperature profiles are presented at various values of the governing parameters. The skin-friction coefficient and the rate of heat transfer are also calculated for different parameter values. Pertinent results are displayed graphically and discussed. It is found that the heat transfer rate improves with an upsurge in a magnetic field but lessens with an elevation in the fluid thermal conductivity.Evaluating the Delamination in the Drilling Process of a Melamine Coated Medium Density Fiberboard (MDF)
https://jacm.scu.ac.ir/article_14900.html
Medium density fiberboard (MDF) is an engineering product that is used in many industrial and general applications such as the furniture industry and kitchen cabinets. Generally, MDF products are generated by screw joints using the drilling process. However, the drilling process of the MDF panels leads to the delamination at the entrance and exit of the drill bit that should be controlled. In this work, the effect of the processing parameters including the feed rate and cutting speed on the delamination of melamine coated MDF is investigated. For this, two different tools with different tool geometry (a brad point drill bit and a commonly used twist drill bit) are examined. Image processing is used to measure the conventional delamination factor together with a new delamination factor referred to as area delamination factor for the drilled holes. It that the delamination value decreases with increasing cutting speed and increases with increasing feed rate. Though, there were some fluctuations in the results. The trend of changing the delamination respect to the investigated parameters was the same for both applied drill bits; however, the smaller value of delamination is obtained using the twist drill bit. Using the proposed area delamination factor, the effect of process parameters on the delamination is presented with higher magnitudes but with the same behavior. This, together with the ability of characterization of the water absorption of drilled holes has made the area delamination factor a more appropriate parameter to evaluate the delamination. The overall results are consistent with previously published works.Thermal-Aerodynamic Performance Measurement of Air Heat Transfer Fluid Mechanics over S-shaped Fins in Shell-and-tube Heat Exchangers
https://jacm.scu.ac.ir/article_15485.html
Forced-convection heat transfer of pure air-fluid inside an open channel as a section of a shell-and-tube heat exchanger is evaluated numerically. S-shaped obstacles are used in the mentioned channel. Airflow inside the channel is considered as a turbulence flow. Governing equations are solved throughout the computational Finite Volume Method (FVM). These equations are analyzed using the standard k-&epsilon; model. The results are designed based on the geometry of S-shaped obstacles. Mentioned results are shown in the form of turbulent kinetic energy (k), turbulent intensity (TI), turbulent viscosity (&mu;t), temperature (T), Nusselt numbers (Nux local, and Nu average), friction coefficients (Cf local, and f average), and the thermal aerodynamic performance factor (TEF), for a Reynolds number (Re) of 12,000 to 32,000. This type of analysis is very useful in many industries and engineering-related problems for getting a good idea about the physical model whenever the analytic solution is out of reach.Effect of Inlet Air Locations on Particle Concentration using Large Eddy Simulation based on Multi Relaxation Time Lattice Boltzmann Method
https://jacm.scu.ac.ir/article_15515.html
In this work, turbulent indoor airflow was considered by Large Eddy Simulation (LES) based on Multi Relaxation Time Lattice Boltzmann Method (MRT-LBM). The Lagrangian approach was utilized to investigate the effect of inlet air location on transport and concentration of different sizes of particles (1-10 &micro;m) in a modeled room. Simulation results showed that for the displacement ventilation system with the inlet air register on the floor, the number of 10&micro;m particles that exit through the outlet is more than the case for the mixing ventilation system with the inlet register on the ceiling. Also, for the latter case, when the inlet air is on the ceiling, the number of suspended 10&micro;m particles in the room is less than for the displacement ventilation system with inlet register on the floor. In addition, the results showed that the location of the inlet air register does not have a considerable effect on the small 1&micro;m particle motion, and the numbers of the particles that remain suspended in the room are roughly the same for both ventilation systems.Numerical Solution of the Time Fractional Reaction-advection-diffusion Equation in Porous Media
https://jacm.scu.ac.ir/article_15019.html
In this work, we obtained the numerical solution for the system of nonlinear time-fractional order advection-reaction-diffusion equation using the homotopy perturbation method using Laplace transform method with fractional order derivatives in Liouville-Caputo sense. The solution obtained is very useful and significant to analyze many physical phenomenons. The present technique demonstrates the coupling of homotopy perturbation method and the Laplace transform technique using He&rsquo;s polynomials, which can be applied to numerous coupled systems of nonlinear fractional models to find the approximate numerical solutions. The salient features of the present work is the graphical presentations of the numerical solution of the concerned nonlinear coupled equation for several particular cases and showcasing the effect of reaction terms on the nature of solute concentration of the considered mathematical model for different particular cases. To validate the reliability, efficiency and accuracy of the proposed efficient scheme, a comparison of numerical solutions and exact solution are reported for Burgers&rsquo; coupled equations and other particular cases of concerned nonlinear coupled systems. Here we find high consistency and compatibility between exact and numerical solution to a high accuracy. Presentation of absolute errors for given examples are reported in tabulated and graphical forms that ensure the convergence rate of the numerical scheme.Thermodynamic and Environmental Assessment of Mounting Fin at the Back Surface of Photovoltaic Panels
https://jacm.scu.ac.ir/article_15524.html
Nowadays, researches on different kinds of renewable energies including photovoltaic technology are developing rapidly. It is proved that the output power of a PV cell is reduced by increasing the temperature. In this paper, mounting aluminum fins at the back surface of the PV module is proposed as a simple and low-cost method to decrease the PV cell temperature. It was found that using aluminum fins caused more than 7&deg;C reduction in the cell temperature. Besides, it was shown that the entropy generation of the PV module with fin, was 3.5% lower than the conventional one. Also, the positive environmental impacts of using fins at the back surface of the PV module were estimated by RETScreen software, so that it, leads to enhance the performance of the PV power plant by more than 25 %, from an environmental viewpoint.Distributed-parameter Dynamic Modeling and Bifurcation Analysis of a Trapezoidal Piezomagnetoelastic Energy Harvester
https://jacm.scu.ac.ir/article_15085.html
In this paper, the effect of the bimorph profile on the nonlinear dynamic behavior and performance of a vibratory piezomagnetoelastic energy harvester is investigated. The proposed model is composed of upper and lower piezoelectric layers on a trapezoidal cantilever beam with one attached tip magnet as well as two external magnets. The magnetic field of two external magnets generates magnetic forces and moment on the tip magnet. The bimorph structure is considered as a distributed-parameter system, and the external forces are obtained by analyzing the magnetic field of the external magnets. Equations of motion are obtained using electromagnetic Lagrange equations based on the generalized Hamilton principle and the Euler-Bernoulli beam theory. The proposed model for the bimorph and magnetic forces is validated by previously published experimental results. In order to compare the nonlinear behavior of the rectangular and trapezoidal beam profiles, the bifurcation diagrams are depicted for various control parameters such as the separation distances of the magnets, beam root width, and beam tip width. Verification of the bifurcation diagrams is performed by the phase plane portraits and Poincare maps. Also, the harvested power level is compared for different profiles of the bimorph. Moreover, the simultaneous effects of exciting frequency and bifurcation parameters on the system performance are investigated by the waterfall diagrams. The obtained results show that the trapezoidal beam profile with a lower tip width has higher performance than the rectangular beam. In trapezoidal beam profiles, the subharmonic and chaotic motions have relatively higher output powers than periodic motions.Effect of Throughflow on the Convective Instabilities in an Anisotropic Porous Medium Layer with Inconstant Gravity
https://jacm.scu.ac.ir/article_15514.html
The significance of inconstant gravity force and uniform throughflow on the start of convective movement in an anisotropic porous matrix is investigated numerically utilizing large-term Galerkin procedure. The porous layer is acted to uniform upright throughflow and inconstant downward gravitational force which changes with the height from the layer. In this study, two types of gravity field digression were examined: (a) linear and (b) parabolic. It is found that the throughflow parameter Pe, the thermal anisotropy parameter &eta;&nbsp;and gravity deviation parameter&nbsp;&lambda; postpone the beginning of convective activity, whereas the mechanical anisotropy parameter&nbsp;&xi; rapids the onset of convective activity. The dimension of the convection cells enhances on enhancing the thermal anisotropy parameter &eta;, the mechanical anisotropy parameter&nbsp;&xi; and gravity deviation parameter&nbsp;&lambda; while, the throughflow parameter Pe decreases the extent of the convective cells. It is also noted that the structure with linear variation of gravity force is more stable.Nonlinear Convective Flow of Maxwell Fluid over a Slendering Stretching Sheet with Heat Source/Sink
https://jacm.scu.ac.ir/article_15143.html
In this study, the features of Maxwell fluid flow through a stretching sheet (variable thickness) with heat source/sink and melting heat transfer are analyzed. Leading equations of the course are transmuted with suitable similarity transmutations and resolved the subsequent equations mathematically with shooting technique. The effects of the valid parameters on the regular profiles (velocity, concentration, temperature) are elucidated through graphs in two cases (presence and absence of melting). And also, friction factor, transfer rates (mass, heat) are examined with the same parameters and the outcomes are presented in tabular form. A few of the findings are (a) the elastic parameter upsurges the velocity (b) heat source parameter raises the temperature (c) mass transfer rate is lowered by chemical reaction.Magneto-bio-thermal Convection in Rotating Nanoliquid containing Gyrotactic Microorganism
https://jacm.scu.ac.ir/article_15676.html
The magneto-convection influenced by a gyrotactic behavior of algal suspensions along with rotation in the nanoliquid layer is investigated. Linear theory based on normal mode analysis is used to find out the inquisitive results of the problem for rigid-free and rigid-rigid boundaries. Both Galerkin-method (Number of terms (N) &gt; 6) and shooting method (by taking forcing condition) are utilized to find the critical value of the Rayleigh number (both thermal and bio) in case of non-oscillatory stability. Both thermal and bio Rayleigh numbers are dependent on each other, thus advance or delay the convection. Rotation and magnetic field slow down the convective motion of microorganisms across the layer and destabilizes the system.Rotating Cylinder Turbulator Effect on the Heat Transfer of a Nanofluid Flow in a Wavy Divergent Channel
https://jacm.scu.ac.ir/article_15732.html
In this research study, the numerical Galerkin Finite Element Method (GFEM) is used for forced laminar convection heat transfer of Cu-water nanofluid in a divergent wavy channel including a rotating cylinder turbulator. The above boundary of the channel is in low temperatures and the bottom boundary is in hot temperatures as well as the cylinder wall temperature. It is assumed that the cylinder rotates in the cavity and makes vortexes to enhance heat transfers. The dimensionless governing equations including velocity, pressure, and temperature formulation are solved by the Galerkin finite element method. The results are discussed based on the governing factors such as nanoparticle volume fraction, Reynolds number, cylinder diameter and rotating velocity. As a main result, among the all studied parameters (Re, u,&nbsp;&Phi; and r), increasing the Re number has the most effect on heat transfer which has 4.8 and 1.6 Average Nu for the cylinder wall and wavy wall, respectively.Polymeric Dissipative Convection Flow from an Inclined Plane with Chemical Reaction: Numerical Study
https://jacm.scu.ac.ir/article_15241.html
An analytical model is developed to study the effects of viscous dissipation and chemical reaction in viscoelastic convection from an inclined plate as a simulation of electro-conductive polymer materials processing. The Jeffery&rsquo;s viscoelastic model is deployed to describe the non-Newtonian characteristics of the fluid and provides a good approximation for polymers, which constitutes a novelty of the present work. The normalized nonlinear boundary value problem is solved computationally with the Keller-Box implicit finite-difference technique. Extensive solutions for velocity, surface temperature and concentration, skin friction, heat, and transfer rates are visualized numerically and graphically for various thermophysical parameters. Validation is conducted with earlier published work for the case of a vertical plate in the absence of viscous dissipation, chemical reaction, and non-Newtonian effects. The boundary layer flow is accelerated with increasing Deborah number whereas temperatures and concentrations are decelerated slightly. Temperatures and concentration are boosted with increasing inclination parameter whereas velocity is lowered. A reverse trend is seen for increasing Richardson&nbsp;number. Increasing chemical reaction reduces velocity and concentration whereas it enhances temperature. Increasing the viscous dissipation parameter is found to enhance velocity and temperature whereas it suppresses concentration.Influence of Thermophysical Features on MHD Squeezed Flow of Dissipative Casson Fluid with Chemical and Radiative Effects
https://jacm.scu.ac.ir/article_16033.html
Theoretical investigation of variable mass diffusivity, thermal conductivity, and viscosity on unsteady squeezed flow of dissipative Casson fluid is presented. Physically, for any effective heat and mass transfer process, a proper account of thermophysical properties in such a system is required to attain the desired production output. The magnetized free convective flow of unsteady Casson fluid encompassing Joule dissipation, radiation, and chemical reactive influence is induced as a result of squeezing property. The governing model assisting the magnetized flow is formulated and transformed via an appropriate similarity transformation. The resulting set of ordinary differential equations is solved numerically using Chebyshev based Collocation Approach (CCA). However, variable viscosity, thermal conductivity, and mass diffusivity effects are seen to diminish the fluid flow velocities, temperature, and concentration respectively along with the lower plate. Heat and mass transfer coefficient, skin friction downsized to an increasing value of variable thermal and mass diffusivity parameters while variable viscosity pronounces the skin friction coefficient. Furthermore, the present analysis is applicable in polymer processing, such as injection molding, extrusion, thermoforming among others.Reduction in Space for Dynamic Finite Element Analysis of Assemblies of Beam-columns when the Mass is Available in Digitized Format
https://jacm.scu.ac.ir/article_15244.html
In 2008, a technique was proposed to reduce run-times in analysis of semi-discretized equation of motion against dynamic excitations available in digitized format. Later, the technique was successfully adapted to reduce numbers of degrees of freedom in finite element analysis of assemblies of beam-columns subjected to static digitized loads. In this paper, attention is paid to dynamic finite element analysis of assemblies of beam-columns. It is shown that, when the mass is available in digitized format, after small modifications in the original technique, the adaptation can simplify the analysis, regardless of the models' sizes, their linearity or non-linearity, and whether the damping is classical or non-classical. The reductions in run-time and in-core memory are considerable, while the changes in accuracy can be negligible.Turbulent Forced Convection and Entropy Generation of Impinging Jets of Water-Al2O3 Nanofluid on Heated Blocks
https://jacm.scu.ac.ir/article_16051.html
A computational analysis on water-Al2O3 nanofluid turbulent forced convection is performed to analyze heat transfer and entropy production in a channel containing heated blocks, cooled by impinging jets. The two phase mixture model (TPMM) is used. The increase in the Reynolds number (Re) and the volume fraction of nanoparticles (&phi;), the decrease in spacing between the heated block (Db) and moving the location of the second jet (J2) to the first jet (J1) contribute to increasing the heat transfer rate (HTR).In addition, the TPMM gives higher values of average Nusselt number (Nu) ̅ than the single-phase model (SPM). The thermal (𝑆𝑔̇ ,𝑡ℎ), frictional (𝑆𝑔̇ ,𝜈) and total (𝑆𝑔̇ ,𝑡) entropy generation values increase with Re and &phi;. When Db is reduced, 𝑆𝑔̇,𝑡 increases. However, 𝑆𝑔̇ ,𝑡 increases when the jet position vary from J2 to J1. Different correlations are proposed for Nu ̅. Our results are compared with data available in the literature.A Hybrid SVM-RVM Algorithm to Mechanical Properties in the Friction Stir Welding Process
https://jacm.scu.ac.ir/article_15253.html
The friction stir welding method is one of the solid-state welding methods for non-homogeneous metals. In this study, the 5XXX series aluminum sample and pure copper are subjected to four passes friction welding process and then the mechanical and metallurgical properties of the welded samples are compared with the prototype. For this purpose, the effect of welding parameters including rotational speed, forward speed and pin angle of the tool is tested by the full factorial method. In this process, hardness estimation and tensile testing are based on input process parameters in order to obtain mechanical properties is an important issue. For this purpose, a mathematical model of mechanical properties must be defined based on the input process parameters. Due to the complex nature of the effect of input process parameters on mechanical properties, this modeling is a complex mathematical problem in which the use of supervised learning algorithms is considered as an efficient alternative. In this paper, a new combination of Relevance Vector Machine (RVM) and Support Vector Machine (SVM) is presented which has a higher degree of accuracy.Magnetohydrodynamic Bio-convective Casson Nanofluid Flow: A Numerical Simulation by Paired Quasilinearisation
https://jacm.scu.ac.ir/article_15273.html
A study on the effects of gyrotactic microorganism and nanoparticles in the bio-convection magnetohydrodynamic flow of Casson fluid at the nonlinear stretching boundary is investigated. Irregular heat source/sink, Joule and viscous dissipations, Brownian motion, and thermophoresis are included in the energy equation. The model outlining the flow system is non-dimensionalised and retained in the same form. The equations are worked out by pairing, i.e. first pair momentum and gyrotactic micro-organism density equation and second pair energy and nanoparticle concentration equation. This technique is termed as a paired quasilinearisation method (PQLM). Convergence and accuracy of PQLM are shown. Obtained numerical results are depicted in graphs in order to observe further insight into the flow pattern. Interesting aspects of various controlling parameters in flow, heat, nanoparticle concentration and microorganism density are discussed.Heating Capacity of an Earth to Air Heat Exchanger in Arid Regions - Experimental Investigation
https://jacm.scu.ac.ir/article_15262.html
Heating capacity of an earth to air heat exchanger EAHE equipped with an exterior fan in the arid region like the Southwest of Algeria is investigated experimentally. In-situ measurement of annual undisturbed subsoil vertical temperature profile is shown that it was 28&deg;C at a depth of 1.5 meters. The EAHE made of 66 meters of PVC tube is demonstrated a heating capacity of 13&deg;C and a cooling capacity of 7&deg;C and a big dependence on local climate conditions. Great potentials and thermal comfort with less energy consumption are represented by earth to air or air-ground heat exchanger in the arid regions like the South of Algeria.MHD Casson Nanofluid Past a Stretching Sheet with the Effects of Viscous Dissipation, Chemical Reaction and Heat Source/Sink
https://jacm.scu.ac.ir/article_14804.html
The effects of viscous dissipation, chemical reaction and activation energy on the two-dimensional hydromagnetic convective heat and mass transfer flow of a Casson nanofluid fluid over a stretching sheet with thermal radiation, have been discussed in detail. The formulated highly nonlinear equations for the above-mentioned flow are converted into first-order ordinary differential equations (ODEs). The shooting method along with Adams-Bash forth Moulton method is used to solve the BVP by using the Fortran language program. The numerical results are computed by choosing different values of the involved physical parameters and compared with earlier published results and excellent validation of the present numerical results has been achieved for local Nusselt number and local Sherwood number. The graphical numerical results of different physical quantities of interest are presented to analyze their dynamics under the varying physical quantities. From the results, it has been remarked that the heat transfer rate escalates for the large values of radiation parameter, viscous dissipation for the Casson nanofluid.Improvement of Numerical Manifold Method using Nine-node Quadrilateral and Ten-node Triangular Elements along with Complex Fourier RBFs in Modeling Free and Forced Vibrations
https://jacm.scu.ac.ir/article_15484.html
In this paper, the numerical manifold method (NMM) with a 9-node quadrilateral element and a 10-node triangular element is developed. Furthermore, complex Fourier shape functions are used to improve the 9-node quadrilateral NMM. Also, the two approaches of higher-order NMM construction are compared, increasing the order of weight functions or local approximation ones; for this purpose, six-node triangular and three-node triangular using second-order and third-order NMM is used. For validation of the suggested method, one free vibration and two forced vibration numerical examples are assessed. The results show that the proposed methods are more accurate than conventional NMM. In addition, the superiority of complex Fourier shape functions compared to classical Lagrange ones in improving accuracy is perceived.Investigation of Nanoﬂuid Natural Convection Heat Transfer in Open Ended L-shaped Cavities utilizing LBM
https://jacm.scu.ac.ir/article_15620.html
In this paper, laminar natural convection of copper/water nanofluid in an open-ended L-shaped cavity is investigated by Lattice Boltzmann Model (LBM). The results are compared by previous studies that are in good agreement. Influences of Rayleigh number (Ra = 103, 104, 105, 106), cavity aspect ratio (AR = 0.2, 0.4, 0.6) and volume concentration of Cu nanoparticles (0 &le;&nbsp;&Phi; &le; 0.1) on the momentum, thermal ﬁelds and heat transfer in the enclosure are studied. Also, the effect of changing the boundary conditions, on the heat transfer rate has been investigated. It is observed that maximum heat transfer enhancement by adding the nanoparticles for Ra = 106 with AR = 0.4 (32.76%) occurs. Results illustrate that increasing the cavity aspect ratio decreases heat transfer rate for Ra = 103&nbsp;and Ra = 104. The least and most heat transfer rate for Ra = 105 occurs in enclosures by aspect ratios of 0.2 and 0.4 respectively, while it was observed at Ra = 106 for minimum and maximum rate of heat transfer the opposite behavior that at Ra = 105 occurs.Investigation of Jeffery-Hamel Flow for Nanofluid in the Presence of Magnetic Field by a New Approach in the Optimal Homotopy Analysis Method
https://jacm.scu.ac.ir/article_15275.html
In this article, numerical study of nanofluid flow between two inclined planes is carried out under the influence of magnetic field. Water-based nanofluid with nanoparticle of Copper (Cu) is taken into consideration for the present investigation. An efficient numerical method namely Optimal Homotopy Analysis Method (OHAM) is employed to get an approximate series solution for the related governing differential equation. A new approach is proposed to determine the convergence controller parameters used in OHAM. For the validation of the proposed technique, the convergence of the obtained results is shown for different values of involved parameters. Moreover, residual errors for the different number of terms in the obtained series solution are represented graphically. Obtained numerical results from the proposed method are incorporated with the previous results and they are found to be in very good agreement. Impacts of involved parameters like nanoparticle volume fraction, Hartmann number and Reynolds number on non-dimensional velocity are also discussed.Frequency Separation in Architected Structures using Inverse Methods
https://jacm.scu.ac.ir/article_16925.html
A major goal in the design of architected structures for low frequency vibration applications (also called mechanical metamaterials, metastructures, elastic metamaterials, auxetic structures) is the creation of regions in the frequency domain where vibration amplitudes are minimal, regardless of the source of excitation. The idea is to provide vibration suppression in manmade structures. The proposed effort is to examine approaches to produce straightforward methods of designing a given mechanical metamaterial to have a specified gap in the frequency spectrum by adjusting its local mass and stiffness values of the individual cells. Previous work in mechanical metamaterial design has focused on using optimization procedures concerned with global vibration suppression. Here our efforts are focused on frequency separation using two direct approaches by interpreting techniques from the areas of model updating and inverse eigenvalue solutions. Rather than examining the overall suppression of vibration, creating specific bandgaps eliminates the possibility of resonance occurring in a given range of excitation frequencies.&nbsp;Design, Analysis and Manufacturing of a Bone Cutting Ultrasonic Horn-Tool and Verification with Experimental Tests
https://jacm.scu.ac.ir/article_15307.html
Horn is one of the main components of ultrasonic cutting systems. The most important characteristics of the horn design are its resonant frequency and amplification factor. Closed-form equations can be used only for the design of simple horns and do not apply to more complex shapes like surgical tools. In This paper, a designing technique based on the finite element method and experimental tests is presented. The conventional design methods are improved, and designing a high performance surgical ultrasonic horn for bone cutting tools is facilitated. The new and complex bone cutting tool has both the knife-edge and toothed-edge, which could cut the bone easily and accurately. The investigations of cutting forces applied to the tool edges show less force in the toothed edge than the knife edge.Heat Transfer Enhancement and Boundary Layer Separations for a Hybrid Nanofluid Flow past an Isothermal Cylinder
https://jacm.scu.ac.ir/article_16949.html
Unsteady magnetohydrodynamic mixed convection flow of an incompressible hybrid nanofluid (Cu-Al2O3/water) past an isothermal cylinder with thermal radiation effect has been studied. Appropriate non-dimensional variables are initiated to reduce the governing equations into a convenient form. By utilizing the procedure of finite difference, reduced equations are then solved for all time. Besides, series solutions are obtained using perturbation technique for short time and asymptotic method for long time which agree with the acquired numerical solution up to a good accuracy. When the mixed convection parameter Ri, radiation conduction parameter Rd, magnetic field parameter M and the volume fractions of nanoparticles ϕ1 and ϕ2 are increased, the local skin friction coefficient and the local Nusselt number are found to increase. Results revealed that the hybrid nanofluid (Cu-Al2O3/water) enhances the heat transfer about 28.28% in comparison to the Al2O3-water nanofluid and about 51.15% than the pure fluid. Contrary to this, the heat transfer of hybrid nanofluid is augmented about 41.76% than the Cu-water nanofluid and 71.41% than the base fluid. The streamlines and isotherms reveal that higher values of Ri, M and Rd delay the boundary layer separation and accordingly shrink the vortices. Moreover, the thermal boundary layer is thickened for the increment of aforesaid quantities. The surface temperature parameter augments the local skin friction coefficient, however, the reverse characteristic is observed for the local Nusselt number.Natural Magneto-velocity Coordinate System for Satellite Attitude Stabilization: The Concept and Kinematic Analysis
https://jacm.scu.ac.ir/article_16951.html
An artificial Earth satellite with an electric charge and an intrinsic magnetic moment is considered. Due to the geomagnetic field, the satellite experiences the influence of the Lorentz and magnetic torques. To set the angular position of the satellite, we introduce natural coordinate system associated with the directions of geomagnetic induction vector and Lorentz force vector which is orthogonal both to the geomagnetic induction and relative velocity of the satellite. It is shown that such a natural magneto-velocity coordinate system is convenient for attitude stabilization of a satellite operating in the mode of scanning the Earth's surface. The properties of the trajectory of the satellite axis on the Earth's surface are analysed. The rotation tensor connecting the natural magneto-velocity and the orbital coordinate systems is obtained. The angular velocity of the natural magneto-velocity trihedron is found. Kinematic differential equations for the unit vectors of the natural magneto-velocity coordinate system are derived.Investigation on the Crack Effect in the Cylinder and Matrix on the Backscattering Field Frequency Specifications using the Finite Element Method
https://jacm.scu.ac.ir/article_15354.html
A novel method to determine the health of the industrial parts is using the ultrasound scattering waves. Any changes in the structure of the scattering object or in the boundary conditions will cause a change in the scattering field. The frequency spectrum of the scattering time signal has valuable information, which is studied by resonant ultrasound spectroscopy (RUS). Since any defect, property changes, or changes in boundary conditions can affect the scattering field. Therefore, the possible defects in the piece are detected using the response of the scattering field. One possible defect in the fiber-reinforced composites is the existence of a crack in the matrix or fibers. In the present study, the effect of crack on the far-field backscattering amplitude spectrum is investigated using the finite element method (FEM). To this end, the effect of the crack&rsquo;s direction in the cylinder and matrix on the form function is scrutinized. The results show that the Rayleigh frequency modes are more sensitive to the cracks existing in the epoxy matrix than the Whispering-gallery frequency modes. Also, the existence of the crack in the aluminum cylinder has the most effect on the Whispering-gallery frequency modes. Besides, the existence of a horizontal crack in the aluminum cylinder leads to a significant reduction in these frequency modes. The validation of the research is determined by comparing the steel cylinder form function obtained from the finite element method&rsquo;s information and the analytical and experimental form functions in addition to the comparison of the aluminum cylinder form function and reference form function.Effect of the Gravity and Magnetic Field to Find Regular Precessions of a Satellite-gyrostat with Principal Axes on a Circular Orbit
https://jacm.scu.ac.ir/article_16955.html
We consider the motion of a magnetized satellite-gyrostat in a circular orbit due to the combined influence of uniform gravity and magnetic fields. Based on the Lagrangian equations, the necessary conditions for the existence of regular precessions are determined in which the axis of precession i\s perpendicular to the orbital plane. All possible regular precessions and permanent rotations are determined and classified. We show the usage of Lagrange equations taking Eulerian angles as generalized coordinates for determining the regular precessions is more effective and accurate than utilization of Euler-Poisson equations.Mathematical Analysis of Poiseuille Flow of Casson Fluid past Porous Medium
https://jacm.scu.ac.ir/article_15394.html
In this article, the influence of microstructure in the Casson fluid flow through a porous medium is investigated, by extending the Buckingham-Reiner&rsquo;s one-dimensional model to plane-Poiseuille flow and Hagen-Poiseuille flow geometries. While analyzing the flow characteristics in single-channel/pipes or multiple channels/pipes of different width/radius, four different probability density functions are used to model the pores widths/radii distributions. It is found that when the pressure gradient increases, the Buckingham-Reiner function raises slowly in the plane-Poiseuille flow, whereas in Hagen-Poiseuille flow, it rises rapidly. In all kinds of distribution of pores, the fluid&rsquo;s mean velocity and porosity of the flow medium are considerably higher in the Hagen-Poiseuille flow than in the plane-Poiseuille flow, and this behavior is reversed for the permeability of the flow medium. The fluid&rsquo;s mean velocity, porosity, and permeability of the flow medium increases appreciably with the rise of the channel width and pipe radius. The porosity of the flow medium slumps with the rise of the periodof the channels and pipes distribution from 1 to 2, and it decreases very slowly with the further rise of the period H of the channels and pipes from 2 to 11.WaveMIMO Methodology: Numerical Wave Generation of a Realistic Sea State
https://jacm.scu.ac.ir/article_16969.html
This paper presents a methodology that allows the numerical simulation of realistic sea waves, called WaveMIMO methodology, which is based on the imposition of transient discrete data as prescribed velocity on a finite volume computational model developed in Fluent software. These transient data are obtained by using the spectral wave model TOMAWAC, where the wave spectrum is converted into a series of free surface elevations treated and processed as wave propagation velocities in the horizontal (x) and vertical (z) directions. The processed discrete transient data of wave propagation velocity are imposed as boundary conditions of a wave channel in Fluent, allowing the numerical simulation of irregular waves with realistic characteristics. From a case study that reproduces the sea state occurring on March 31st, 2014, in Ingleses Beach, in the city of Florian&oacute;polis, state of Santa Catarina, Brazil, it was concluded that the WaveMIMO methodology can properly reproduce realistic conditions of a sea state. In sequence, the proposed methodology was employed to numerically simulate the incidence of irregular realistic waves over an oscillating water column (OWC) wave energy converter (WEC). From these results, the WaveMIMO methodology has proved to be a promising technique to numerically analyze the fluid-dynamic behavior of WECs subjected to irregular waves of realistic sea state on any coastal region where the device can be installed.Thermal Performance of Oscillating Blade with Various Geometries in a Straight Channel
https://jacm.scu.ac.ir/article_15420.html
In this study, the effect of stationary and oscillating blades on the forced convection heat transfer in a channel is studied numerically. Simulations are performed in a fully-developed, laminar, unsteady, and incompressible flow with Reynolds number and Prandtl number equal to 100 and 1, respectively. The effects of the blade geometry, oscillating speed and oscillation angle on heat transfer and pressure drop are studied. The results are presented in terms of time-averaged Nusselt number, temperature, and vorticity distribution and the pressure drop. The results indicate that the oscillation angle, oscillating speed of the blade, and the number of the blades, affect the thermal performance of the channel. In most cases, it is observed that the effect of the oscillation angle is more than that for the oscillating speed on heat transfer enhancement. However, increasing the number of blades does not necessarily help to enhance the heat transfer, but it can slightly decrease the pressure drop.Size Effect on Inclined Cracking in Unidirectional Composites
https://jacm.scu.ac.ir/article_16992.html
The fracture and size effect properties of the unidirectional (UD) laminae were investigated based on the fracture energy analysis. The crack propagations on inclined fiber orientation may result in different energy release mechanisms. Therefore, the size effect behavior of these types of failures may vary according to the fracture parameters of the UD composites. This study aims to develop a fracture analysis of UD plies with inclined fibers relative to the loading axis. A numerical work with a developed material model was conducted to predict the size effect trends. The size effect law was used to fit the strength reduction with increasing size. The fundamentals of the quasibrittle fracture mechanics are shown to be applicable to analyze these types of structures. It is shown that the composite structures as quasibrittle materials, can exhibit a significant size effect.Buckling and Vibration Analysis of a Double-layer Graphene Sheet Coupled with a Piezoelectric Nanoplate
https://jacm.scu.ac.ir/article_15421.html
In this article, the vibration and buckling of a double-layer Graphene sheet (DLGS) coupled with a piezoelectric nanoplate through an elastic medium (Pasternak and Winkler models) are investigated. DLGS are subjected to biaxial in-plane forces and van der Waals force existing between each layer. Polyvinylidene fluoride (PVDF) piezoelectric nanoplate is subjected to an external electric potential. For the sake of this study, sinusoidal shear deformation theory of orthotropic plate expanded with Eringen&rsquo;s nonlocal theory is selected. The results indicate that nondimensional frequency and nondimensional critical buckling load rise when the ratio of width to thickness increases. Furthermore, incrementing the effect of elastic medium parameter results in increasing the stiffness of the system and, consequently, rising nondimensional frequency and critical buckling load.Body of Optimal Parameters in the Weighted Finite Element Method for the Crack Problem
https://jacm.scu.ac.ir/article_17020.html
In this paper, a high-accuracy weighted finite element method is constructed and investigated for finding an approximate solution of the crack problem. We consider an approximation of the Lam&eacute; system in the domain with the reentrant corner 2&pi; at the boundary. A new concept of definition of the solution of the problem is introduced. It allows us to suppress the influence of the singularity on the accuracy of finding an approximate solution, in contrast to the classical approach. We have introduced a weight function into the basis of the finite element method. The accuracy of finding an approximate solution by the weighted finite element method depends on three input parameters. We created an algorithm and establish the body of optimal parameters in the weighted finite element method for the crack problem. The choice of parameters from this set allows us to accurately and stability find an approximate solution with the smallest deviation from the best error. This is required to generate industrial codes.Computational Fluid Dynamic Analysis of Amphibious Unmanned Aerial Vehicle
https://jacm.scu.ac.ir/article_15424.html
Unmanned Aerial Vehicles (UAVs) are becoming popular due to its versatile maneuvering and high pay load carrying capabilities. Military, navy and coastal guard makes crucial use of the amphibious UAVs which includes the working functionalities of both hover craft and multi-rotor systems. Inculcation of these two systems and make it as amphibious UAV for water quality monitoring, sampling and analysis is essential to serve the human-kind for providing clean water. On this note, an amphibious UAV is designed for carrying a water sampler mechanism with an on-board sensor unit. In order to examine the stability of designed UAV under diverse wind load conditions and to examine the aerodynamic performance characteristics, computational fluid dynamic analysis (CFD) is performed. For various flight conditions such as pitch, roll, yaw and hovering, the flow characteristics around the vehicle body is examined. The aerodynamic phenomenon at the rotor section, vortex, turbulent regions, wake and tip vortex are identified. In addition, CFD analysis are conducted to determine the thrust forces during forward and hovering conditions through varying the wind speed 3 to 10 m/sec and speed of rotor 2000 to 5000 rpm. The effect of non-dimensional parameters such as advance ratio and induced inflow ratio on estimating the thrust characteristics are studied. Simulation results suggested that at 5&deg; angle of attack and 8 m/sec wind speed condition, the aerodynamic performance of the vehicle is superior and stable flight is guaranteed. The amphibious UAV with flying and gliding modes for collecting water samples in remote water bodies and also in-situ water quality measurement can be well utilized for water quality monitoring.Design of Doubly Salient Permanent Magnet Generator for Output Power Enhancement using Structural Modification
https://jacm.scu.ac.ir/article_17066.html
The doubly salient permanent magnet generator (DSPMG) is widely known as an efficient machine for electrical production from renewable energy. In this paper, we aim to improve the output power of the DSPMG using a structural modification, which is targeted for low-speed electrical generations. Structural parameters including the stator pole depth, thickness of permanent magnet, stator pole arc, and number of winding turns were adjusted, then an optimal value of those parameters was selected based on the characteristics of the generator tested during no-load and on-load conditions. Simulations were based on the finite element method. The generator was targeted to be used for the rated power of 200 W. It was found that the optimally designed generator had a higher electromotive force of 36.1%, a lower cogging torque of 20%, and a higher output power of 12.2% than the conventional structure. The leakage flux of the proposed structure was also improved from the conventional one. Thus, the generator designed in this work could be another capable choice for electrical generation from renewable energy. The proposedly modified technique can also be adapted for output profile improvement of the doubly salient permanent magnet machines which are extensively used for renewable energy production nowadays.Theoretical and Experimental Investigation on Mechanical Behavior of Aluminum to Aluminum Tubular Bonded Lap Joint under Pure Torsion and a Finite Element Comparison with Hybrid Rivet/Bonded Joint
https://jacm.scu.ac.ir/article_15433.html
The combination of mechanical and bonded joints creates a new connection type, called hybrid joint which has the benefits of both mechanical and bonded joints. In this research, the mechanical behavior of the tubular bonded lap joint between aluminum tubes subjected to pure torsion has been investigated experimentally and numerically, and the results have been compared. The mechanical behavior of the hybrid (rivet/bonded) joint has been investigated numerically and the outcomes have been compared. The adhesive and rivets have cohesive elements and bushing connector elements, respectively. The results from the hybrid joints and the damage mechanism show that the rivets change the interface shear stress and the stress distribution of the joint, and affect the joint&rsquo;s torque capacity and strengths. It has been observed that for specimens with overlap lengths close to effective length, the hybrid joint is more effective.A New Solution for the Classical Problem of a Rigid Body Motion in a Liquid
https://jacm.scu.ac.ir/article_17074.html
We consider the problem of the motion of a rigid body-gyrostat immersed in an incompressible ideal fluid. Based on Yehia's study [1, 2], the equations of the motion of the problem are introduced and they are reduced to the orbital equation. This reduced equation may be used to study the stability of certain motions of the body [3] and to obtain solutions for the classical problems in rigid body dynamics [4]. Using the orbital equation, a single new solution of the considered problem is obtained in which the angle between the body axis of symmetry and the vertical axis is constant.Simulation of Hydraulic Fracture Propagation in Fractured Coal Seams with Continuum-discontinuum Elements
https://jacm.scu.ac.ir/article_17078.html
Creating new fracture networks in coal seams with natural fractures through hydraulic fracturing techniques is an effective method for exploiting coal-bed methane. In this paper, a continuum-discontinuum element method (CDEM) is developed for simulating and assessing hydraulic fracture propagation in coal seams. An elastic-damage-fracture model is proposed for capturing the deformation and cracking processes of fractured coal. A stress-fracture percolation relation is implemented to simulate the hydro-mechanical coupling processes. The influence of X-direction angles, mechanical strengths, distances and lengths of natural fractures are analyzed in detail. The results are potentially useful to optimize the fracturing design.Analysis of Axisymmetric Vibration of Functionally-Graded Circular Nano-Plate Based on the Integral Form of the Strain Gradient Model
https://jacm.scu.ac.ir/article_16930.html
In this paper, it is aimed to analyze the linear vibrational behavior of functionally-graded (FG) size-dependent circular nano-plates using the integral form of the non-local strain gradient (NSG) model. The linear axisymmetric vibration of the circular FG nano-plates based on the non-local strain gradient (NSG) model is the focal point of this study. In this regard, the non-local elasticity theory (NET) and strain gradient (SG) models are used in conjunction with Hamilton's principle to obtain the governing equations. Discretization of the obtained governing equations is performed with the help of generalized differential quadrature rule (GDQR) and Galerkin weighted residual method (GWRM). The analysis is focused on the effect of non-local and material parameters, as well as the aspect ratio, heterogeneity index of FG material, different boundary conditions, and frequency number on the overall behavior of nano-plate. On using the Galerkin method, a system of linear differential equations is obtained and solved to determine the natural linear frequencies and mode shapes. The obtained results are then compared with the existing results in the literature. On using the proposed procedure in this paper, the dynamic behavior of nano-plate under different boundary conditions can be well described. In addition, the existing deficiencies in other non-local theories can be eliminated. The results of this investigation can be considered as a turning point in the improvement of theoretical results for achieving a better prediction of vibrational behavior in nanostructures.Experimental and Finite Element Study to Determine the Mechanical Properties and Bond Between Repair Mortars and Concrete Substrates
https://jacm.scu.ac.ir/article_15470.html
The separation between repair mortars and the concrete substrate is one of the serious problems in repairing concrete structures. One of the main causes of this separation is the lack of proper curing and, consequently, excessive shrinkage of the repair mortar, which reduces the bond strength between the concrete substrate and the repair layer and has an adverse effect on the compressive and tensile strength of the repair mortars. In this paper, the mechanical properties, shrinkage of repair mortars, as well as their shear and tensile bond strength is investigated on the concrete substrate of different ages under the curings of "abandoned in the laboratory space," "water-submerged" and "curing agent." In-situ "friction-transfer" and "pull-off" methods are used to measure adhesion. Furthermore, the relationships between compressive strength, tensile strength, and readings are obtained from "friction-transfer" and "pull-off" methods on repair mortars and the stress distribution method used in the above-mentioned methods are presented using nonlinear finite element analysis (Abaqus/CAE). The results indicate a significant effect of curing method on shrinkage and mechanical properties of repair mortars; as a result, effective curing increases the shear and tensile bond strength at the substrate and repair layer joint boundary. It is also observed that there is a linear relationship between the experimental results obtained from the two methods used in this study with a high correlation coefficient, highly consistent with the results obtained from nonlinear finite element analysis. Thus, they can be used as in-situ methods for determining the compressive and tensile strength of repair mortars.Turbulent energy cascade through equivalence of Euler and Lagrange motion descriptions and bifurcation rates
https://jacm.scu.ac.ir/article_16991.html
This work analyses the homogeneous isotropic turbulence by means of the equivalence between Euler and Lagrange representations of motion, adopting the bifurcation rates associated with Navier-Stokes and kinematic equations, and an appropriate hypothesis of fully developed chaos. The equivalence of these motion descriptions allows to show that kinetic and thermal energy cascade arise both from the convective term of Liouville equation. Accordingly, these phenomena, of nondiffusive nature, correspond to a transport in physical space linked to the trajectories divergence. Both the bifurcation rates are properly defined, where the kinematic bifurcation rate is shown to be much greater than Navier-Stokes bifurcation rate. This justifies the proposed hypothesis of fully developed chaos where velocity field and particles trajectories fluctuations are statistically uncorrelated. Thereafter, a specific ergodic property is presented, which relates the statistics of fluid displacement to that of velocity and temperature fields. A detailed analysis of separation rate is proposed which studies the statistics of radial velocity component along the material separation vector. Based on previous elements, the closure formulas of von Karman-Howarth and Corrsin equations are finally achieved. These closures, of nondiffusive kind, represent a propagation phenomenon, and coincide with those just presented by the author in previous works, corroborating the results of these latter. This analysis applies also to any passive scalar which exhibits diffusivity.A Closed-Form Solution for Electro-Osmotic Flow in Nano-Channels
https://jacm.scu.ac.ir/article_15479.html
In this article&lrm;, &lrm;a fluid dynamic code is implemented to investigate a non-linear model for electro-osmotic flow through a one-dimensional Nano-channel&lrm;. &lrm;Certain mathematical techniques are simultaneously utilized to convert the coupled system of equations into a non-linear differential correlation&lrm;. &lrm;This correlation is based on the mole fraction of anion&lrm;. &lrm;By using a modified homotopy perturbation method&lrm;, &lrm;the achieved non-linear differential equation is converted into a few linear differential equations&lrm;. &lrm;The mole fraction of anion across the channel is found by solving the linear differential equations&lrm;. &lrm;Finally&lrm;, &lrm;the distribution of the mole fraction of cation&lrm;, &lrm;electrical potential, and velocity are accurately derived based on the mole fraction of anion&lrm;. &lrm;The present study confirms that by application of a modified homotopy perturbation method&lrm;, &lrm;the results are in acceptable agreement with the previously validated data&lrm;. &lrm;However, using the proposed method here&lrm;, &lrm;a closed-form of the solution is achieved&lrm;.Scattering and Backscattering Study of Mechanical Plane Wave in Composite Materials Plates (Earth model 1066B and LiNbO3)
https://jacm.scu.ac.ir/article_15486.html
Reflection and refraction phenomenon pattern of elastic plane wave at the interface between anisotropic monoclinic elastic half-space and isotropic elastic half-spaces is studied. Closed-form expression for phase velocity is obtained. Reflection and transmission coefficients are obtained using the method of Cramer's rule in determinant form. Also, the energy ratios are calculated in terms of reflection and transmission coefficients. Numerical examples are considered to exhibit all the findings graphically. The energy conservation law is implemented at each angle of incidence to validate the numerical results, and it is found that energy ratios are in good agreement with the energy conservation law.Haar Wavelet Method for Solving High-Order Differential Equations with Multi-Point Boundary Conditions
https://jacm.scu.ac.ir/article_15499.html
In This paper, the developed Haar wavelet method for solving boundary value problems is described. As known, the orthogonal Haar basis functions are applied widely for solving initial value problems, but In this study, the method for solving systems of ODEs associated with multipoint boundary conditions is generalized in separated or non-separated forms. In this technique, a system of high-order boundary value problems of ordinary differential equations is reduced to a system of algebraic equations. The experimental results confirm the computational efficiency and simplicity of the proposed method. Also, the implementation of the method for solving the systems arising in the real world for phenomena in fluid mechanics and construction engineering approves the applicability of the approach for a variety of problems.Chaos Control in Gear Transmission System using GPC and SMC Controllers
https://jacm.scu.ac.ir/article_15500.html
Chaos is a phenomenon that occurs in some non-linear systems. Therefore, the output of the system will be heavily dependent on the initial conditions. Since the main characteristic of the chaos is an abnormal behavior of the system output, it should be considered in designing control systems. In this paper, controlling chaos phenomenon in a time-variant non-linear gear transmission system is investigated. To do this, a non-linear model for the system is introduced considering the effective parameters of the system, and then it is shown that chaos appears in the system by plotting phase plane of state-space variables. It should be noted that there is a great difference between random and chaotic behavior. In random cases, the model or input contains uncertainty, and therefore, the system behavior and output are not predictable. However, in chaotic behavior, there is only a brief uncertainty in the system model, input or initial conditions, and designing controller based on output prediction could be achieved. Therefore, model predictive control (MPC) algorithms are used to control the chaos, using the output prediction concept. In many cases, perturbation term also can be considered as uncertainty, and therefore, a robust controller family can be used for eliminating chaos. Both generalized predictive controller (GPC) and sliding mode controller (SMC) are used for chaos control here. The simulation results show the efficiency of the proposed algorithms.Numerical Scheme based on Non-polynomial Spline Functions for the System of Second Order Boundary Value Problems arising in Various Engineering Applications
https://jacm.scu.ac.ir/article_15501.html
Several applications of computational science and engineering, including population dynamics, optimal control, and physics, reduce to the study of a system of second-order boundary value problems. To achieve the improved solution of these problems, an efficient numerical method is developed by using spline functions. A non-polynomial cubic spline-based method is proposed for the first time to solve a linear system of second-order differential equations. Convergence and stability of the proposed method are also investigated. A mathematical procedure is described in detail, and several examples are solved with numerical and graphical illustrations. It is shown that our method yields improved results when compared to the results available in the literature.Hydrodynamic Behavior in Solar Oil Heat Exchanger Ducts Fitted with Staggered Baffles and Fins
https://jacm.scu.ac.ir/article_15502.html
The attachment of turbulators, such as baffles, fins, ribs, bars, and blocks, inside the thermal solar receiver ducts, is among the most effective mechanisms for important thermal exchange by creating the turbulence, extending the trajectory of the flow, increasing the surface of heat exchange, forcing recycling cells, and hence a high thermal exchange. The solar finned and baffled heat exchangers are employed in a wide application interval, and it is important to examine the design of a duct for this configuration of the flow field and its effect on the heat transport phenomenon. In This study, dynamic field simulations are reported in horizontal rectangular form ducts, using three obstacles with oil HTF (heat transfer fluid). Two various finned and baffled duct configurations are treated, i.e., case (A) with one fin and two baffles, and case (B) with two fins and one baffle. Different hydrodynamic fields, i.e., X-velocity and Y-speed, as well as various X-velocity profiles in many flow stations, related to Re value, are analyzed. A computational approach is applied in order to simulate the oil flow, using finite volume (FV) integration method, SIMPLE discretization algorithm, QUICK interpolation scheme, Standard k-epsilon turbulence model, and ANSYS FLUENT 12.0 software. Simulation results reported an unstable flow structure, with powerful recycling cells, on the backsides of each fin and baffle, as a result of fluid detachment at their upper front sharp edges, in both studied models (A and B). As expected, the first duct model, i.e., Case A, has better X- and Y-velocity values, due to its large recirculation regions. In This paper, many physical phenomena, such as the turbulence, instability, flow separation, and the appearance of reverse secondary currents, are reported. As its data confirmed by many previous numerical and experimental results, the suggested new models of finned and baffled heat exchangers filled with high thermal conductivity oil, allow an improvement in the dynamic thermal-energy behavior of many thermal devices such as flat plate solar collectors.Metal and Metallic Oxide Nanofluid over a Shrinking Surface with Thermal Radiation and Heat Generation/Absorption
https://jacm.scu.ac.ir/article_15518.html
In transport as well as manufacturing industries, the two basic aspects are heating and cooling. The use of metal or metallic oxide nanofluids has an effective cooling technique than that of conventional fluids. Therefore, the work is aimed at describing the three-dimensional MHD flow of metal and metallic oxide nanofluids past a stretching/shrinking sheet embedding with a permeable media. Further, thermal properties are enhanced by incorporating heat generation/absorption and radiative heat energy in the heat equation, enhancing the efficiency of temperature profiles. The convective boundary condition for temperature is used, which affects the temperature profile. Suitable similarity transformation is used to transform the governing equations to ordinary differential equations. The approximate analytical solution is obtained for these transformed differential equations employing the Adomian Decomposition Method (ADM). The influences of characterizing parameters are obtained and displayed via graphs, and the computation results of the heat transfer rate for various values of constraints are shown in a table. It is observed that both the momentum and energy profiles decrease with an enhance in the porosity parameter. Also, the fluid temperature decreases with an increasing thermal radiation parameter, but the opposite effect is encountered for the energy generation/absorption parameter.Elastic Limit Angular Velocity and Acceleration Investigation in Non-Uniform Rotating Disk under Time-Dependent Mechanical Loading
https://jacm.scu.ac.ir/article_15526.html
An analytical effort is made to achieve cognition on the effect of time-dependent mechanical loading &lrm;on the stress fields of rotating disks with non-uniform thickness and density. At high variable angular &lrm;velocities and accelerations, evaluation of the effect of shear stress on the values of von Mises stress is &lrm;significant and it is excellent to consider shear stress in this equivalent stress calculation alongside the &lrm;radial and tangential stress. In the proposed analytical model, the Homotopy perturbation method (HPM) &lrm;solves the general structure of rotating disks equilibrium equations in both radial and tangential &lrm;directions. HPM is an efficient tool to solve linear and nonlinear equations, providing solutions in quick &lrm;converging series. The results obtained through this process are then confirmed using the finite &lrm;difference method and the exact solution in the literature. The effect of parameters in angular velocity &lrm;and acceleration functions with the parameter in the thickness function and the effect of boundary &lrm;conditions on the values of elastic limit angular velocity and acceleration are established by performing &lrm;numerical examples. Furthermore, the effect of shear stress on the maximum values of &lrm;von Mises stress is discussed. It is shown that shear stress has more influence on the distribution of &lrm;equivalent von Mises stress in the elastic region. It is shown the introduced analytical model is useful for &lrm;evaluating rotating disk with any arbitrary shape of thickness and density function, without using the &lrm;commercial finite element simulation software.Stability Analysis of Casson Nanofluid Flow over an Extending/Contracting Wedge and Stagnation Point
https://jacm.scu.ac.ir/article_15528.html
This numerical study is conducted to scrutinize the dual solutions and stability analysis of the flow of Casson nanofluid past a permeable extending/contracting wedge and stagnation point. Momentum, heat and mass transfer behaviors of the Casson nanofluid have been modeled with the use of the Buongiorno nanofluid model. Suitable self-similarity variables are employed to convert the fluid transport equations into ordinary differential equations and the bvp4c MATLAB solver is used to solve the equations. The impacts of active parameters on fluid transport properties are illustrated graphically. The outcomes of the present analysis reveal that the influence of Casson fluid parameter on velocity and temperature distributions obtained from the first and second solutions exhibit the opposite natures. From the stability analysis, it is found that the thermophoresis and Brownian motion effects acquire the same critical point value on Nusselt number. The temperature distribution of the Casson nanofluid is higher over the wedge than stagnation point. The two solutions are found for the limited range of extending/contracting parameter. The detailed stability test is carried out to determine which of the two solutions is physically realizable and stable.Optimization of Air Distribution Patterns by Arrangements of Air Inlets and Outlets: Case Study of an Operating Room
https://jacm.scu.ac.ir/article_15534.html
In this research, possible methods to improve the air distribution patterns of an operating room (OR) employing CFD method are investigated. Laminar airflow (LAF), turbulent airflow (TAF), and LAF with the air curtain are examined. It is found that LAF and LAF with the air curtain cases are superior to TAF-based cases. The study shows that the LAF and LAF with the air curtain cases as the proposed configurations have an acceptable capability to maintain the indoor air conditions within the range recommended by the standards. According to the simulations, the LAF with the air curtain case is the most suitable case in terms of the contamination risk, and it is recommended to be implemented in the existing OR.A New Modified Hamilton-Crosser and Nan Models for Thermal Conductivity of Different Lengths Carbon Nanotubes Water-based Nanofluids
https://jacm.scu.ac.ir/article_15535.html
In order to investigate the shape effect of nanoadditives on thermal conductivity of nanofluids, different length carbon nanotubes (CNTs) are made and using a two-step method, different nanofluids are prepared. The CNTs are cut into different lengths by functionalization at different refluxing times of 1, 2 and 4 hours. To probe the effect of aspect ratio of CNTs on the obtained experimental data, modified Hamilton-Crosser and Nan models are developed. It is found that the original Hamilton-Crosser and Nan models could not predict the experimental thermal conductivities. By replacing n = 6 + xL/D&nbsp;instead of the shape factor of n=6 in the Hamilton- Crosser, where L and D were length and diameter of CNTs and also by replacing&nbsp;&phi;&nbsp;(xL/D) instead of &phi;&nbsp;(volume fraction) in the Nan model, the prediction of modified equations show very good accordance with the experimental data which means the shape of nanoadditives has high impact on nanofluids&rsquo; properties.Multi-objective Optimization of Shot-peening Parameters using Design of Experiments and Finite Element Simulation: A Statistical Model
https://jacm.scu.ac.ir/article_15536.html
Shot-peening is a mechanical surface treatment used extensively in the industry to enhance the performance of metal parts against fatigue. Thus, it is important to determine main parameters of shot-peening in order to obtain its optimal values. The purpose of this study is to achieve a statistical model to determine the important parameters of the shot-peening process by considering the effect of sample thickness on the responses and achieving the multi-objective optimal parameters. To do this, response surface methodology are used to determine the governing models between the response variable and the input parameters. Shot velocity, shot diameter, coverage percentage and sample thickness are selected as shot-peeningparameters. Residual compressive stress, its depth and roughness are considered as the response variable. Using finite element analysis, shot-peening process are simulated. The desirability function approach is used for multi-objective optimization so that the optimal shot-peeningparameters, which simultaneously provide two response variables in optimal mode, are obtained. The results show that surface stress and maximum residual stress are independent of shot velocity, whereas, the depth of the compressible stress and roughness are directly related to shot velocity. In addition, thickness modifies surface stress and the depth of the compressible stress. The optimal conditions for surface stress, maximum compressive stress, and roughness simultaneously with high-coverage and low-velocity can be achieved as well.A Comparative Study on the Efficiency of Compiled Languages and MATLAB/Simulink for Simulation of Highly Nonlinear Automotive Systems
https://jacm.scu.ac.ir/article_15549.html
In the present paper, a comparison between the simulation performance of a highly nonlinear model in MATLAB/Simulink and a compiled language has been drawn. A complete powertrain layout was formed in Simulink and the same model was developed from scratch in Fortran 2003 which led to creating a complete simulation software program named Powertrain Simulator. The results show that for a system with not many details and phase changes, both of the simulation environments offer acceptable performance. However, when the modeling layout is overly complicated, developing the model in a compiled language is a smarter choice.Thermal Analysis of Radiating Film Flow of Sodium Alginate using MWCNT Nanoparticles
https://jacm.scu.ac.ir/article_15577.html
Heat transfer of fluids plays an important role in process flows, as this has significant impacts in process configurations, energy pricing and utilization. Therefore, this paper, the heat and mass transfer of a radiating non-Newtonian Sodium alginate transported through parallel squeezing plates is examined. The radiating-squeezing fluid flows through the parallel plates arranged vertically against each other with multi walled carbon nanotube (MWCNT) particles. Transport mechanics and thermal conditions of the Sodium alginate is studied using systems of coupled nonlinear models. This higher order, governing ordinary differential models are used to analyze the thermal and mass transfer of the nanofluid using the adomian decomposition method. Results obtained from analytical study displayed graphically are used to investigate effect of thermal radiation on film flow of MWCNT nanoparticles on the Sodium alginate. As revealed from result, concentration increase of MWCNT nanoparticles increases thermal profile significantly. This can be physically explained owing to increasing concentration, increases thickness of thermal boundary due to conductivity enhancement of fluid. Improved thermal diffusivity drops thermal gradient which reduces heat transfer. Whereas, radiation effect on fluid transport shows decrease in heat transfer as thermal conductivity becomes lower than temperature gradient of the flow. Obtained analysis when compared against other methods of solution (numerical and approximate analytical) proves satisfactory. Therefore, the results obtained from the work provides a good basis for the application and improvement of the Sodium alginate in medical, pharmaceutical and manufacturing industries among other practical application.Effect of Cattaneo-Christov Heat Flux on Radiative Hydromagnetic Nanofluid Flow between Parallel Plates using Spectral Quasilinearization Method
https://jacm.scu.ac.ir/article_15631.html
In this paper, we numerically solve the equations for hydromagnetic nanofluid flow past semi-infinite parallel plates where thermal radiation and a chemical reaction are assumed to be present and significant. The objective is to give insights on the important mechanisms that influence the flow of an electrically conducting nanofluid between parallel plates, subject to a homogeneous chemical reaction and thermal radiation. These flows have great significance in industrial and engineering applications. The reduced nonlinear model equations are solved using a Newton based spectral quasilinearization method. The accuracy and convergence of the method is established using error analysis. The changes in the fluid properties with various parameters of interest is demonstrated and discussed. The spectral quasilinearization method was found to be rapidly convergent and accuracy is shown through the computation of solution errors.&nbsp;Numerical Study of Three-dimensional Boundary-layer Flow over a Wedge: Magnetic Field Analysis
https://jacm.scu.ac.ir/article_15643.html
The magnetohydrodynamic flow of a viscous fluid over a constant wedge in three- dimensional boundary-layer has been analyzed both numerically and asymptotically. The magnetic field is applied normal to the flow. The mainstream flows aligned with wedge surface are assumed to be proportional to the power of the coordinate distances. The system is described using three-dimensional MHD boundary-layer equations which are converted to couple nonlinear ordinary differential equations using similarity transformations. The resulting equations are solved numerically using the Keller-box method which is second-order accurate and asymptotically for far-field behavior. Both numerical and asymptotic solutions give good agreement in predicting the velocity behaviors and wall shear stresses. The effects of Hartmann number, pressure gradient and shear-to- strain-rate on the velocity fields are studied. Particularly, it is shown that the solutions of three-dimensional boundary-layer for variable pressure gradient exist, its effects are important on the boundary-layer flow. Results show that there are new families of solutions for some range of shear-to-strain-rate and there exists a threshold value of it beyond which no solutions exist. For some range of parameters, there is a reverse flow at which our boundary-layer assumptions are no longer valid. Various results for the velocity profiles, wall-shear stresses and displacement thicknesses are also obtained. The physical mechanisms behind these results are discussed.Analytical Solutions and Analyses of the Displacement Separating Point in Diffusers
https://jacm.scu.ac.ir/article_15663.html
The main purpose of this study is to develop an understanding of the turbulent boundary layer calculation to analyze displacement of the separating point in diffusers. An approximate method has been used which is based on an analogy with the rheological power law and is applied in the study of non-linear viscous flows. At first, the method has been validated with the experimental data in the same experimental cases study. An appropriate geometric with and without the Nano-fluids in the straight-wall and curved-wall conical diffusers has been investigated. Its analyses output was compared with the results obtained by a numerical code. Also, the proposed method is more practical and can be used in diffuser design procedures.Twin Screw Expanders Profile Optimization Using Surrogate-Based Modelling
https://jacm.scu.ac.ir/article_15667.html
Twin screw machines can be used as an expander to recover the lost power in various processes causing pressure energy loss. Twin screw expanders (TSEs) have caught the attention of many researchers due to low capital, maintenance and operation costs, long lifespan and their application in two-phase fluids. However, substantial efforts required to enhance their performance. This research describes the optimization of the profile of a TSE with 4-6 lobe configuration - using surrogate-based modeling (SBM). To do so, based on the in-house code developed within FORTRAN, a TSE profile is designed and validated against available data. Then, a mathematical model is developed viaof experiments (DOE). Next, the effects of four main profile parameters are investigated on the expander performance in the entire design space. Finally, an optimized combination of parameters is offered using a multi-objective genetic algorithm. 3D computational fluid dynamics (CFD) results show that the optimized profile had more than 7% exergy efficiency compared to the base profile.Higher-Order Slope Limiters for Euler Equation
https://jacm.scu.ac.ir/article_15684.html
High-resolution schemes are designed for resolving shocks without significant numerical dissipation and dispersion. Achieving higher-order and high-resolution is a challenging task because of the non-monotonicity of the higher-order schemes. In this article, we have presented second-order and third-order slope limiters having an improved shock resolution and accuracy. The present limiters are tested on one-dimensional and two-dimensional unstructured grids and compared with the existing limiters. The numerical result shows that the present limiters have an excellent shock resolving property and accuracy than other limiters. In blast wave problems, it has shown over 200% more accurate results than the other limiters.Nonlinear Primary Frequency Response Analysis of Self-Sustaining Nanobeam Considering Surface Elasticity
https://jacm.scu.ac.ir/article_15686.html
This paper is focused to investigate the effects of nonlinear sources, including viscoelastic foundation and geometrical nonlinearity along with the surface elasticity and residual surface stress effects on the primary frequency response of a harmonically excited nanoscale Bernoulli-Euler beam. Due to large surface-area-to-volume ratio, the theory of surface elasticity as well as residual surface stress effects are taken into account within the beam models. The Galerkin approach accompanied by trigonometric shape functions is utilized to reduce the governing PDEs of the system to ODEs. The multiple scales perturbation method theory is applied to compute the nonlinear frequency response of nanobeam. The effects of linear and nonlinear viscoelastic damping coefficient of the medium, crystallographic directions of [100] and [111] of anodic alumina, geometrical nonlinear term and geometrical property on the nonlinear primary frequency response of nanoscale beam are investigated. The results show that theses parameters have a significant effect on the nonlinear frequency response of nanobeams in the case of primary resonance.&nbsp;Non-similar Radiative Bioconvection Nanofluid Flow under Oblique Magnetic Field with Entropy Generation
https://jacm.scu.ac.ir/article_15687.html
Motivated by exploring the near-wall transport phenomena involved in bioconvection fuel cells combined with electrically conducting nanofluids, in the present article, a detailed analytical treatment using homotopy analysis method (HAM) is presented of non-similar bioconvection flow of a nanofluid under the influence of magnetic field (Lorentz force) and gyrotactic microorganisms. The flow is induced by a stretching sheet under the action of an oblique magnetic field. In addition, nonlinear radiation effects are considered which are representative of solar flux in green fuel cells. A second thermodynamic law analysis has also been carried out for the present study to examine entropy generation (irreversibility) minimization. The influence of magnetic parameter, radiation parameter and bioconvection Rayleigh number on skin friction coefficient, Nusselt number, micro-organism flux and entropy generation number (EGN) is visualized graphically with detailed interpretation. Validation of the HAM solutions with published results is also included for the non-magnetic case in the absence of bioconvection and nanofluid effects. The computations show that the flow is decelerated with increasing magnetic body force parameter and bioconvection Rayleigh number whereas it is accelerated with stronger radiation parameter. EGN is boosted with increasing Reynolds number, radiation parameter and Prandtl number whereas it is reduced with increasing inclination of magnetic field.Characterization of the Nonlinear Biaxial Mechanical Behavior of Human Ureter using Constitutive Modeling and Artificial Neural Networks
https://jacm.scu.ac.ir/article_15696.html
Characterization of the mechanical properties of soft biological tissues is a fundamental&nbsp;issue in a variety of medical applications. As such, constitutive modeling of biological tissues that serves to establish a relationship between the kinematic variables has been used to formulate the tissue&rsquo;s mechanical response under various loading conditions. However, the validation of the developed analytical and numerical models is accompanied by a length of computation time. Hence, the need for new advantageous methods like artificial intelligence (AI), aiming at minimizing the computation time for real-time applications such as in robotic-assisted surgery, sounds crucial. In this study, at first, the mechanical nonlinear characteristics of human ureter were obtained from planar biaxial test data, in which the examined specimens were simultaneously loaded along their circumferential and longitudinal directions. To do so, the biaxial stress-strain data was used to fit the well-known Fung and Holzapfel-Delfino hyperelastic functions using the genetic optimization algorithm. Next, the potential of Artificial Neural Networks (ANN), as an alternative method for prediction of the mechanical response of the tissue was evaluated such that, multilayer perceptron feedforward neural network with different architectures was designed and implemented and then, trained with the same experimental data. The results showed both approaches were practically able to predict the ureter nonlinearity and in particular, the ANN model can follow up the tissue nonlinearity during the entire loading phase in both low and high strain amplitudes (RMSE&lt;0.02). Such results confirmed that neural networks can be a reliable alternative for modeling the nonlinear mechanical behavior of soft biological tissues.A Simple Approach for Dealing with Autonomous Conservative Oscillator under Initial Velocity
https://jacm.scu.ac.ir/article_15713.html
The current study is involved to analytical solution of nonlinear oscillators under initial velocity. By using energy conservation principle, system initial condition converts to condition which oscillator&rsquo;s velocity become zero. When oscillator&rsquo;s speed is zero and placed out of movement&rsquo;s origin, the relation between frequency and amplitude could be extracted. By paying attention to energy conservation principle and relation between the initial velocity and amplitude, the frequency-amplitude relation is extended to frequency-initial velocity relationship. In order to demonstrate the effectiveness of proposed method, Duffing oscillator with cubic nonlinearity and oscillator with discontinuity are considered. Comparison of results with numerical solution shows good agreement. The proposed method is simple and efficient enough to achieve the analytical approximation of nonlinear autonomous conservative oscillator with initial velocity.Transient Response of Longitudinal Fins under Step Changes in Base Temperature and Heat Flux using Lattice Boltzmann Method
https://jacm.scu.ac.ir/article_15760.html
The present article reports the transient response of longitudinal fins having linear and non-linear temperature dependent thermal conductivity, convection coefficient and internal heat generation under two cases of base boundary condition, (i) step change in base temperature and (ii) step change in base heat flux. The fin tip is assumed to be adiabatic. Both, linear and non-linear, temperature dependency of thermo-physical properties is addressed in the mathematical formulation and the solution for the above cases is obtained using Lattice Boltzmann method (LBM) implemented in an in-house source code. LBM, being a dynamic method, simulates the macroscopic behavior by using a simple mesoscopic model and offers enormous advantages in terms of simple algorithm to handle even the most typical of boundary conditions that are easy and compact to program even in case of complicated geometries too. Although the transient response of longitudinal fins has been reported earlier, however power law variation of thermophysical properties for the above two base condition has not been reported till date. The present article first establishes the validity of LBM code with existing result and then extends the code for solving the transient response of the longitudinal fin under different sets of application-wise relevant conditions that have not been treated before. Results are reported for several combination of thermal parameter and are depicted in form of graphs.An Experimental Comparison between Wing Root and Wingtip Corrugation Patterns of Dragonfly Wing at Ultra-low Reynolds Number and High Angles of Attack
https://jacm.scu.ac.ir/article_15936.html
This study presents the empirical comparison between the wing root and wingtip corrugation patterns of dragonfly wing in the newly-built wind-tunnel at the IAUN. The main objective of the research is to investigate the effect of wingtip and wing root corrugations on aerodynamic forces and the flow physics around the cross-sections at Re=10000 and the angle of attack of 0&deg; to 30&deg;. For this aim, two cross-sections are extracted from wing root (first cross-section) and wingtip (second cross-section). The first cross-section has corrugations with higher density than the second cross-section. The comparison of lift coefficients obtained from pressure distribution and force measurement indicates an acceptable agreement between the results. Also, Particle Image Velocity (PIV) technique is used to measure the velocity field. The results show that all corrugation patterns do not have positive effects on the aerodynamic forces. The second cross-section can generate considerable aerodynamic forces compared to the first cross-section. At &alpha;=25&deg;, the lift coefficient generated by the second cross-section is 90% and 25% higher than that of the first cross-section and the flat plate, respectively. Based on results, corrugations in the wing root's vicinity have a crucial role in the solidity of insect wings; however, corrugations in the wing tip's vicinity play a vital role in generating adequate aerodynamic forces. The comparison conducted in the current research reveals the second cross-section is an appropriate replacement for the flat plate in MAVs due to generating more essential forces for flight.Optimization of Spark Ignition Engine Performance using a New Double Intake Manifold: Experimental and Numerical Analysis
https://jacm.scu.ac.ir/article_16030.html
In this study, the effect of different intake manifold geometries on the performance of a spark-ignited engine is investigated both numerically and experimentally. 1D and 1D-3D simulations are carried out to find the optimal dimensions of different intake manifold designs. The numerical simulations are successfully validated with real data. The results show that the manifold design utilizing two-valve throttle has a better performance. The superior design is constructed and mounted on the engine to compare the output result with the base design. The operation tests are performed at various rotational speeds in the range of 1000-6000 rpm. Regarding the experimental tests, the superior double intake manifold increases the engine brake power and torque by 6.814%.&nbsp;Combined Impacts of Fin Surface Inclination and Magnetohydrodynamics on the Thermal Performance of a Convective-Radiative Porous Fin
https://jacm.scu.ac.ir/article_16073.html
In this work, the combined impacts of magnetohydrodynamics and fin surface inclination on thermal performance of convective-radiative porous fin with temperature-invariant thermal conductivity is numerically study using finite difference method. Parametric studies reveal that as the inclination of fin, convective, radiative, magnetic and porous parameters increase, the adimensional fin temperature decreases which leads to an increase in the heat transfer rate through the fin and the thermal efficiency of the porous fin. It is established thatthe porous fin is more efficient and effective for low values of convective, inclination angle, radiative, magnetic and porous parameters. The thermal performance ratio of the fin increases with the porosity parameter.&nbsp;A New Approach for Exergoeconomics Evaluation by Considering Uncertainty with Monte Carlo Method
https://jacm.scu.ac.ir/article_16189.html
The exergoeconomics analysis combines thermodynamic assessments based on exergy analysis with economic concepts. this article suggests a new method for exergoeconomics analysis and evaluation of energy systems by considering uncertainty in economic parameters. As the first step, the future values of economic parameters that influence the operating cost of the energy system are forecasted by the Monte Carlo Method. Then, as a novel approach, principles of exergoeconomics analysis method are coupled with the Monte Carlo Method for exergoeconomics evaluation of energy systems. Also, three new parameters, i.e. Risk Factor (RF), Risk Factor Sensitivity (RFS), and Product Cost Sensitivity (PCS), are proposed. Two different approaches are considered in the evaluation process to improve the system: a) decreasing the total cost of products and b) reducing the risk of the cost of products. Also, the proposed method is applied to the CGAM system as a benchmark. Eventually, the results of the first and second approaches show that the total cost of products can be reduced 4.1% (from 22.270 $/GJ to 21.358 $/GJ) and also the risk of the cost of the products can be reduced 5.8% (from 25.8% to 24.3%).An Exact Analytical Solution for Heat Conduction in a Functionally Graded Conical Shell
https://jacm.scu.ac.ir/article_16222.html
In this study, an exact analytical solution for the heat conduction problem in a truncated conical shell is presented. The cone is made of functionally graded materials and it is considered that the material properties vary according to power-law functions. The general thermal boundary conditions are applied to cover a wide variety of actual applications. The results are successfully validated. Two examples, which are tried to mimic practical conditions, are studied using the derived solution, and a parametric study is done to shed light on the problem. The outcomes of this research provide useful information for understanding the nature of heat transfer behavior in the specific geometry of a cone. Regarding the specific applications of conical shells, the results can be used in the prefabrication process of these shells and tailoring the design parameter of functionally graded materials.MHD Non-Newtonian Fluid Flow past a Stretching Sheet under the Influence of Non-linear Radiation and Viscous Dissipation
https://jacm.scu.ac.ir/article_16509.html
This work reports the heat and mass transfer of the 2- D MHD flow of the Casson and Williamson motions under the impression of non-linear radiation, viscous dissipation, and thermo-diffusion and Dufour impacts. The flow is examined through an extending zone along with inconsistent thickness. The partial differential equations are extremely nonlinear and lessen to ODEs throughout of the appropriate similarity transformation. The system of nonlinear and coupled ODEs is handled applying a numerical approach with shooting procedure. Numerical solutions for momentum and energy descriptions are deliberated through graphs and tabular form for the impacts of magnetic parameter, Soret and Dufour variables, momentum power index variable, Schmidt number, wall thickness variable, without dimensions velocity slip, heat jump and mass jump variable. Outcomes illustrate that the momentum, temperature, and concentration transfer of the laminar boundary layers of equally non-Newtonian liquid motions are non-consistent. A comparison made with the existing literature which shows an good agreement and confidence of the present outcomes. It shows that Casson parameter restricted the skin friction, local heat and mass transfer while l enhanced the skin friction, local heat and mass transfer. Velocity slip constant decreases the skin friction, local heat and mass transfer and a similar observation for thermal slip constant while an opposite phenomena for the solutal slip constant.&nbsp;Nonstandard Dynamically Consistent Numerical Methods for MSEIR Model
https://jacm.scu.ac.ir/article_16581.html
In this paper, two numerical methods for solving the MSEIR model are presented. In constructing these methods, the non-standard finite difference strategy is used. The new methods preserve the qualitative properties of the solution, such as positivity, conservation law, and boundedness. Numerical results are presented to express the efficiency of the new methods.Theoretical Investigation of Viscosity and Thermal Conductivity of a Gas along a Non-isothermal Vertical Surface in Porous Environment with Dissipative Heat: Numerical Technique
https://jacm.scu.ac.ir/article_16667.html
The prime objective of the current investigation is to explore the variation of viscosity and thermal conductivity impacts on MHD convective flow over a moving non-isothermal vertical plate in presence of the viscous-dissipative heat and thermal-radiation. The compatible transformation of similarity are employed to obtain the non-linear ODE with the appropriate boundary conditions from the governing equations and the numerical solution of the boundary value problem so obtained are solved via MATLAB bvp4c solver. Naturally, the fluid viscosity and thermal-conductivity may vary from liquid to metal with temperatures and therefore, the impact of viscosity and thermal-conductivity in this investigation is quite significant. The physical parameters along with several influences on momentum, temperature, and concentration are explicated and portrayed with graphs. In addition, the velocity, temperature and concentration gradients at the surface are evaluated and displayed in tabular form. A decent agreement is found in the present outcomes with previously issued work. Furthermore, it is found that the growth of the thermal-radiation increases the gas temperature. The present study is useful for various industrial applications like metal and polymer extrusion, continuous casting, cooling process, nuclear plant and many more.Numerical and Experimental Investigation on Post-buckling Behavior of Stiffened Cylindrical Shells with Cutout subject to Uniform Axial Compression
https://jacm.scu.ac.ir/article_16692.html
In this paper, post buckling behavior of thin steel and aluminum cylindrical shells with rectangular cutouts under axial loading was studied experimentally and also using the finite element method. Riks method is used for analyzing the cylindrical shells. The effect of longitudinal and circumferential stiffeners (ribs and stringer) was studied on the buckling load and the post buckling behavior as the stiffeners used individually and in combination with each other. It was shown that by adding stringer, the buckling load improves and the rib has a positive effect on the post buckling behavior of the structure. Some tests were performed by ZwickRoell tensile/compression testing machine and it was carried out for both types of steel and aluminum shells with and without stiffeners. Comparing the experimental results with the FEA results shows good agreement. Nonlinear analysis of cylindrical steel and aluminum shells with cutout have demonstrated that, in some cases, a local buckling called snap-back can be seen in the load-displacement path. Snap-back which is a decrease in the amount of both load and displacement indicates this local buckling. This phenomenon is because of appearing mode shapes sequentially during the numerical buckling analysis of shells. Although these local buckling happened, the structure is still endured the higher loads.Free Convection of Micropolar Fluid over an Infinite Inclined Moving Porous Plate
https://jacm.scu.ac.ir/article_16703.html
The present paper analyzes free convective heat and mass transfer of non-conducting micropolar fluid flow over an infinitely inclined moving porous plate in the presence of heat source and chemical reaction. Moreover, the effect of thermal radiation is also taken care of in the same study. The present investigation is relevant to the fabrication system in industries corresponding to the materials composed with high-temperature. Similarity technique is adopted with similarity variable to transform the non-dimensional form of the partial differential equations into ordinary differential equations. To get the approximate solution of these transformed complex nonlinear set of ODEs we have employed fourth order Runge&ndash;Kutta method in conjunction with shooting technique. The validation of the present result as well as critical issues is addressed in the discussion section refereeing to the previously published work as a particular case. The behavior of physical parameters governs the flow phenomena are displayed via graphs and tables.Potential of Semi-Empirical Heat Transfer Models in Predicting the Effects of Equivalence Ratio on Low Temperature Reaction and High Temperature Reaction Heat Release of an HCCI Engine
https://jacm.scu.ac.ir/article_16712.html
In this paper, the influence of equivalence ratio on the low-temperature reaction heat release (LTR-HR) and high-temperature reaction heat release (HTR-HR) of homogeneous charge compression ignition engine has been experimentally and numerically examined. The numerical study was performed using zero-dimensional (0D) single-zone model by considering the chemical kinetic of fuel combustion. Annand, Woschni, Hohenberg, Chang (Assanis), and Hensel semi-empirical heat transfer models were employed in the 0D single-zone simulations. In this study, the in-cylinder pressure, rate of heat release, LTR-HR and HTR-HR were investigated. The Hensel heat transfer model was the only model that predicted the combustion in all of the operating conditions. The Hohenberg model properly recognized the effects of equivalence ratio changes on the HTR-HR.A Novel Flexible Lane Changing (FLC) Method in Complicated Dynamic Environment for Automated Vehicles
https://jacm.scu.ac.ir/article_16757.html
Decision making and path planning in case of highly transient dynamics of the surrounding as well as the effect of road condition are the issues that are not completely solved in the previous researches. The goal is to perform a safe and comfortable lane change that includes flexible re-planning capabilities. In this paper, a novel structure for path planning and decision making part of a vehicle automatic lane change has been introduced which comprehensively considers both longitudinal and lateral dynamics of the vehicle. The presented method is able to perform re-planning even in the middle of a lane change maneuver according to new traffic condition. Inclusion of the dynamics of all involved vehicles and providing online performance are the other advantages of the proposed system. The algorithm is simulated and various scenarios are constructed to evaluate the efficiency of the system. The results show that the system has completely acceptable performance.Performance Investigation of Simple Low-dissipation AUSM (SLAU) Scheme in Modeling of 2-D Inviscid Flow in Steam Turbine Cascade Blades
https://jacm.scu.ac.ir/article_16773.html
This study evaluates the performance of the SLAU, AUSM+UP upwind schemes, and CUSP artificial dissipation scheme for the flow through the convergent-divergent nozzles and turbine stator blades under different pressure ratios by developing an in-house code. By comparing the results with analytical and experimental results, it is found that, despite the simplicity of the SLAU scheme in the absence of tuning variables, it provides reasonable predictions for different turbine blades in point of location and strength of the shocks. The SLAU scheme could converge at a much higher rate, leading to very much lower values of residuals. The SLAU scheme causes about 30% and 20% improvements over the prediction of the shock-induced losses in supersonic and subsonic outlet flows, respectively.Theoretical Study on Poiseuille Flow of Herschel-Bulkley Fluid in Porous Media
https://jacm.scu.ac.ir/article_16840.html
This theoretical study analyses the effects of geometrical and fluid parameters on the flow metrics in the Hagen-Poiseuille and plane-Poiseuille flows of Herschel-Bulkley fluid through porous medium which is considered as (i) single pipe/single channel and (ii) multi&ndash;pipes/multi-channels when the distribution of pores size in the flow medium are represented by each one of the four probability density functions: (i) Uniform distribution, (ii) Linear distribution of Type-I, (iii) Linear distribution of Type-II and (iv) Quadratic distribution. It is found that in Hagen-Poiseuille and plane-Poiseuille flows, Buckingham-Reiner function increases linearly when the pressure gradient increases in the range 1 - 2.5 and then it ascends slowly with the raise of pressure gradient in the range 2.5 - 5.In all of the four kinds of pores size distribution, the fluid&rsquo;s mean velocity, flow medium&rsquo;s porosity and permeability are substantially higher in Hagen-Poiseuille fluid rheology than in plane-Poiseuille fluid rheology and, these flow quantitiesascend considerably with the raise of pipe radius/channel width and a reverse characteristic is noted for these rheological measures when the power law index parameter increases.The flow medium&rsquo;s porosity decreases rapidly when the period of the pipes/channels distribution rises from 1 to 2 and it drops very slowly when the period of the pipes/channels rises from 2 to 11.A Deep Learning Approach to Predict the Flow Field and Thermal Patterns of Nonencapsulated Phase Change Materials Suspensions in an Enclosure
https://jacm.scu.ac.ir/article_16903.html
The flow and heat transfer of a novel type of functional phase change nanofluids, nano-&lrm;encapsulated phase change suspensions, is investigated in the present study using a deep neural &lrm;networks framework. A deep neural network was used to learn the natural convection flow and &lrm;heat transfer of the phase change nanofluid in an enclosure. A dataset of flow and heat transfer &lrm;samples containing 3290 samples of the flow field and temperature distributions was used to &lrm;train the deep neural network. The design variables were fusion temperature of nanoparticles, &lrm;Stefan number, and Rayleigh number. The results showed that the proposed combination of a &lrm;feed-forward neural network and a convolutional neural network as a deep neural network could &lrm;robustly learn the complex physics of flow and heat transfer of phase change nanofluids. The &lrm;trained neural network could estimate the flow and heat transfer without iterative and costly &lrm;numerical computations. The present neural network framework is a promising tool for the design &lrm;and prediction of complex physical systems&lrm;.Theoretical Study of Convective Heat Transfer in Ternary Nanofluid Flowing past a Stretching Sheet
https://jacm.scu.ac.ir/article_16910.html
A new theoretical tri-hybrid nanofluid model for enhancing the heat transfer is presented in this article. This model explains the method to obtain a better heat conductor than the hybrid nanofluid. The tri-hybrid nanofluid is formed by suspending three types of nanoparticles with different physical and chemical bonds into a base fluid. In this study, the nanoparticles TiO2, Al2O3 and SiO2 are suspended into water thus forming the combination TiO2-SiO2-Al2O3-H2O. This combination helps in decomposing harmful substances, environmental purification and other appliances that requires cooling. The properties of tri-hybrid nanofluid such as Density, Viscosity, Thermal Conductivity, Electrical Conductivity and Specific Heat capacitance are defined mathematically in this article. The system of equations that governs the flow and temperature of the fluid are converted to ordinary differential equations and are solved using RKF-45 method. The results are discussed through graphs and it is observed that the tri-hybrid nanofluid has a better thermal conductivity than the hybrid nanofluid.A Modified Couple Stress-Based Model for the Nonlinear Vibrational Analysis of Nano-Disks Using Multiple Scales Method
https://jacm.scu.ac.ir/article_16935.html
In this article, the nonlinear vibrational behavior of a nano-disk was analyzed using the multiple scales method (MSM). The modified couple stress theory was used to consider the small-scale effect via the application of nonlocal parameter. Employing Hamilton's principle, two coupled nonlinear differential equations were derived based on the nonlinear von-K&aacute;rm&aacute;n strain-displacement relation and the classical plate theory. The Galerkin-based procedure was utilized to obtain a Duffing-type nonlinear ordinary differential equation with a cubic nonlinear term and solved by the application of MSM. The effects of nonlocal parameter, aspect ratio, different boundary conditions, and the nonlinear shift frequencies, were obtained on the overall behavior of the nano-disk. Results indicate that increasing the central dimensionless amplitude of the nano-disk, the nonlinear frequency, and the shift index exhibit an increasing behavior, while the increase in the non-dimensional nonlocal parameter, causes a decrease in the nonlinear frequency ratios and the shift index. Additionally, the increase in h/r increases the effect of dimensionless central amplitude on the nonlinear frequencies ratios. Additionally, comparison of the current results with those previously published in the literature shows good agreements. This indicates that the MSM can ease up the solution, and hence, can be applied to the solution of nonlinear nano-disks with high accuracy.Numerical Study on the Ferrofluid Droplet Splitting in a T-junction with Branches of Unequal Widths using Asymmetric Magnetic Field
https://jacm.scu.ac.ir/article_16956.html
Research on the microdroplet splitting phenomenon has intensified in recent years. Microdroplet splitting has numerous applications in chemical synthesis, biology, and separation processes. The current paper covers the numerical study of ferrofluid microdroplet splitting at various lengths and velocities inside the T-junction with branches of unequal widths under asymmetric magnetic fields. Microdroplet splitting can be controlled by using an asymmetric magnetic field and the asymmetry in the width of T-junctions branches. Three geometrical models of the T-junction with different widths ratio (0.7, 0.85, and 1), along with a magnetic field with various intensities are studied. This magnetic field is generated by a line dipole. In this study, the distance between the dipole and origin is kept constant. The splitting ratio of ferrofluid microdroplets at different velocities (different capillary numbers), different non-dimensional lengths and different magnetic force (different magnetic Bond numbers) at the center of T-junction are calculated for each amount of branch width. The results are verified with previous works and their correctness is proved. The splitting ratio is defined as the volumetric ratio of the larger daughter droplet to the mother droplet. The results indicate that generally, the stronger the asymmetric magnetic force is, the more asymmetric the splitting will become, with the splitting ratio becoming closer to 1. Also, as asymmetry increases between the widths of the two branches of the T-junction, the splitting ratio approaches 1.On the Analytical and Computational Methodologies for Modelling Two-wheeled Vehicles within the Multibody Dynamics Framework: A Systematic Literature Review
https://jacm.scu.ac.ir/article_16970.html
In this paper, a literature review on two-wheeled vehicle systems is methodically performed and presented. For this purpose, the principal aspects concerning the kinematic, dynamic, control, and identification features of articulated mechanical systems described within the multibody formulation approach are emphasized in this review article. First, the scientific investigations on two-wheeled vehicle modelling are chronologically described employing a historical literature review approach. This is done to set a consistent context for the subsequent developments analyzed in the paper. Then, following the systematic literature review methodology described in this work, a rich corpus of relevant documents in the time span between 2013-present. Moreover, bibliometric methods are used to construct the conceptual structure map of the research field, which also allowed for formulating a thematic classification. Thus, considering the full-texts of the identified corpus of documents, this work presents a synthetic analysis of the fundamental issues about the multibody approaches for modelling two-wheeled vehicles. Finally, future research perspectives are pointed out in this articleDynamic Response of Functionally Graded Carbon Nanotube-Reinforced Hybrid Composite Plates
https://jacm.scu.ac.ir/article_16974.html
Dynamic instability behavior of functionally graded carbon nanotube reinforced hybrid composite plates subjected to periodic loadings is studied. The governing equations of motion of Mathieu-type are established by using the Galerkin method with reduced eigenfunctions transforms. With the Mathieu equations, the dynamic instability regions of hybrid nanocomposite plates are determined by using the Bolotin&rsquo;s method. Results reveal that the dynamic instability is significantly affected by the carbon nanotube volume fraction, layer thickness ratio, bending stress, static and dynamic load parameters. The effects of important parameters on the instability region and dynamic instability index of hybrid nanocomposite plates are discussed.Size Effect on the Axisymmetric Vibrational Response of Functionally Graded Circular Nano-Plate Based on the Nonlocal Stress-Driven Method
https://jacm.scu.ac.ir/article_17033.html
In this work, the axisymmetric-vibrational behavior of a size-dependent circular nano-plate with functionally graded material with different types of boundary conditions was investigated. The analysis was performed based on the Stress-driven model (SDM) and Strain-gradient theory (SGT) in conjunction with classical plate theory. The governing equations of motion and their corresponding equations for boundary conditions were obtained based on Hamilton&rsquo;s principle and solved using the generalized differential quadrature rule. Results show that this method is applicable to the vibrational analysis of such structures with a fast convergence rate; as N approaches 6 for the first mode, and 10 for the second as well as the third and fourth modes, regardless of the type of boundary condition. In both models, the influences of various parameters such as size-effect parameter Lc, material heterogeneity index n, and types of boundary conditions were obtained on the first four modes and compared with each other. Results indicate that the natural frequencies in these modes increase with an increase in the heterogeneity index n, and size-effect parameter Lc. Additionally, these parameters appear to have a stiffening effect on the nano-plate vibrational behavior. However, for a nano-plate resting on a knife or simply supported edge, in the first mode, the SDM shows a more stiffening effect on the plate behavior as compared with the SGT. Nonetheless, for the clamped and free edge boundary conditions, both models predicted the same behavior. The SGT showed a higher-stiffening effect only in the fourth mode, for all types of considered boundary conditions.Magnetized Bi-convective Nanofluid Flow and Entropy Production Using Temperature-sensitive Base Fluid Properties: A Unique Approach
https://jacm.scu.ac.ir/article_17080.html
The flow mechanism and entropy production of a bi-convective, magnetized, radiative nano-liquid flow for an inverted cone considering temperature-sensitive water properties is accomplished numerically. The functional nanomaterial comprises Copper, Alumina in the base liquid, water. The mathematical equations representing the system's physical characteristics are solved numerically by adopting a robust numerical approach for indulgencing non-similar solutions to understand numerous parameters' effect on temperature, velocity, salient gradients, and entropy production. The investigation summarizes that buoyancy force and injection heighten the velocity, and suction, particle percentage, radiation elevate the heat transfer. At the same time, the radiation and Brinkman number enhance the entropy generation. It is also detected from this investigation that the magnetic effect shows dual behaviour in entropy generation.Development of an Educational Code of Deriving Equations of Motion and Analyzing Dynamic Characteristics of Multibody Closed Chain Systems using GNU Octave for a Beginner
https://jacm.scu.ac.ir/article_17099.html
In this study, an automatic GNU Octave code, a free high-level language, for the educational purposes was developed to derive equations of motion and constrain equations of a multibody closed chain system and to calculate the response of the system. The code for calculating the dynamic response was developed by formulating several equations in symbolic expression and extracting differential-algebraic equations in matrix form. The code has a similar structure to the previous code for the open chained system, but it deals with the constraint equation and different numerical integration. The examples of closed chain systems provide an additional procedure to derive the constraint equations by using Lagrangian multiplication theory and to solve the differential-algebraic equations using the Runge-Kutta method. The code was made to understand the theory of analysis and the structure of calculation easily. In addition, the code has an automatic process of the derivation of the Lagrange equation and the constraint equations in matrix form after inputting the number of symbolic information such as position and velocity coordinates and design variables of the system that the user wants to review. The code was validated by comparing the dynamic response of the four-bar linkage with the same design variables and initial conditions of the previous work. By using the code, the reader's ability to exchange information such as symbols and matrices will be expected to be improved.Prediction Capabilities of a One-dimensional Wall-flow Particulate Filter Model
https://jacm.scu.ac.ir/article_17101.html
This work is focused on the formulation of a numerical model for prediction of flow field inside a particulate filter. More specifically, a one-dimensional mathematical model of the gas flow in a particulate trap-cell is deduced and solved numerically. The results are given in terms of velocity, pressure, and filtration velocity. In addition, the dependence of the pressure drop on the main governing parameters has been investigated. More specifically, the permeability of the porous medium and the hydraulic diameter play a fundamental role in the pressure drop.Computational Enhancement of a Mixed 3D Beam Finite Element with Warping and Damage
https://jacm.scu.ac.ir/article_17104.html
This paper describes the computational aspects of the beam Finite Element formulation recently developed by the authors to simulate the nonlinear response of structural members subjected to shear and torsion, accounting for cross-section warping. The paper focuses on an efficient consistent solution algorithm that by-passes the iterative procedure required in force-based and mixed Finite Elements and makes the model easy to be implemented in a standard code. Moreover, it proposes a new non-iterative technique to condense out the stress components derived by the three-dimensional constitutive response and not directly included in the fiber section formulation. The efficiency and accuracy of the proposed numerical model are validated by simulating the response of steel and reinforced concrete structural members.Mixed Convection Heat Transfer and Entropy Generation in a Water-Filled Square Cavity Partially Heated from Below: Effect of the Richardson and Prandtl numbers
https://jacm.scu.ac.ir/article_17105.html
In the present study, fluid flow, heat transfer, and entropy generation for mixed convection inside a water-filled square cavity were investigated numerically. The sidewalls of the cavity, which move upwards, are kept at low-temperature 𝑇𝑐 while only a part in the center of the bottom wall is kept at high-temperature 𝑇ℎ and the remaining parts are kept adiabatic. The governing equations, in stream function&ndash;vorticity form, are discretized and solved using the finite difference method. Particular attention was paid to the influence of the Prandtl numbers of 5.534, 3.045, and 2, corresponding respectively to the water temperatures of 303,15 K, 333,15 K, and 363,15 K. The numerical results are presented in the form of streamlines, isotherms, and entropy generation contours for different values of the Richardson numbers at an arbitrary Reynolds number Re=102. Besides this, the evolution of the average Nusselt number and the average entropy generation is also reported. The obtained results show interesting behaviors of the flow and thermal fields, which mainly involve stable symmetric and non-symmetric steady-state solutions, as well as unsteady regimes, depending on specific values of the Richardson and Prandtl numbers. It is additionally observed that the average Nusselt number increases and the average entropy generation decreases when both the Richardson and Prandtl numbers increase.Investigation of Aspen Properties at Elevated Temperature
https://jacm.scu.ac.ir/article_17107.html
The results of dynamic compression tests of aspen under elevated temperature up to +60&deg;C are presented. The tests were carried out based on the Kolsky method using the split Hopkinson pressure bar. To study the anisotropy of properties, aspen samples were fabricated and tested by cutting along and across the fibers direction. Dynamic stress-strain curves were obtained as well as the average values of modulus of active loading sites. The greatest steepness of the loading branches and the highest breaking stresses are observed for the samples loaded along the fiber direction, while the smallest values are noted under loading across the fiber direction. Also the effect of elevated temperature on strength and deformation properties of aspen is estimated.