Journal of Applied and Computational MechanicsJournal of Applied and Computational Mechanics
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Feed provided by Journal of Applied and Computational Mechanics. Click to visit.Viscoelastic Micropolar Convection Flows from an Inclined Plane with Nonlinear Temperature: A ...
http://jacm.scu.ac.ir/article_14296_1889.html
An analytical model is developed to study the viscoelastic micropolar fluid convection from an inclined plate as a simulation of electro-conductive polymer materials processing with nonlinear temperature. Jeffery’s viscoelastic model is deployed to describe the non-Newtonian characteristics of the fluid and provides a good approximation for polymers. Micro-structural is one of the characteristics of non-Newtonian fluid that represents certain 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, angular velocity, skin friction, heat transfer rate and wall couple stress 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. This particle study finds applications in different industries like reliable equipment design, nuclear plants, paint spray, thermal fabrication, water-based gel solvents, polymeric manufacturing process, gas turbines and different propulsion devices.Tue, 31 Mar 2020 19:30:00 +0100Exact Solution for Nonlinear Local Fractional Partial Differential Equations
http://jacm.scu.ac.ir/article_14550_1889.html
In this work, we extend the existing local fractional Sumudu decomposition method to solve the nonlinear local fractional partial differential equations. Then, we apply this new algorithm to resolve the nonlinear local fractional gas dynamics equation and nonlinear local fractional Klein-Gordon equation, so we get the desired non-differentiable exact solutions. The steps to solve the examples and the results obtained, showed the flexibility of applying this algorithm, and therefore, it can be applied to similar examples.Tue, 31 Mar 2020 19:30:00 +0100Effect of Corrugated Baffles on the Flow and Thermal Fields in a Channel Heat Exchanger
http://jacm.scu.ac.ir/article_14531_1889.html
The performance of corrugated baffles inserted in a rectangular channel heat exchanger is investigated. The fluid flows and thermal distribution are determined via numerical simulations. The working fluid has a shear thinning behavior. The influence of the baffle design is explored, we interest to the “wavy” shape. The corrugation angle of baffle (α) is changed from 0° (i.e. a straight baffle) to 45°. Also, the height (h) of the corrugated baffle is changed and three cases are considered, namely: h/H = 0.4, 0.5 and 0.6, where “H” is the channel height. In comparison with the unbaffled channel, the overall performance factor has increased from 1.27 up to 1.53 when the corrugation angle is increased from 0° to 45°. Concerning the corrugation height, the predicted results allowed us to select the case h/H = 0.5 as the best configuration from the cases studied.Tue, 31 Mar 2020 19:30:00 +0100Efficient Solution of Nonlinear Duffing Oscillator
http://jacm.scu.ac.ir/article_14428_1889.html
In this paper, the efficient multi-step differential transform method (EMsDTM) is applied to get the accurate approximate solutions for strongly nonlinear duffing oscillator. The main improvement of EMsDTM which is to reduce the number of arithmetic operations, is thoroughly investigated and compared with the classic multi-step differential transform method (MsDTM). To illustrate the applicability and accuracy of the new method, six case studies of the free undamped and forced damped conditions are considered. The periodic response curves of both MsDTM and EMsDTM methods are obtained and contrasted with the exact solution or the numerical solution of Runge Kutta 4th order (RK4) method. This approach can be easily extended to other nonlinear systems and therefore is widely applicable in engineering and other sciences.Tue, 31 Mar 2020 19:30:00 +0100Implicit RBF Meshless Method for the Solution of Two-dimensional Variable Order Fractional ...
http://jacm.scu.ac.ir/article_14509_1889.html
In the present work, the numerical solution of two-dimensional variable-order fractional cable (VOFC) equation using meshless collocation methods with thin plate spline radial basis functions is considered. In the proposed methods, we first use two schemes of order O(τ2) for the time derivatives and then meshless approach is applied to the space component. Numerical results obtained from solving considered model on regular and irregular domains, demonstrate the accuracy and efficiency of the proposed schemes.Tue, 31 Mar 2020 19:30:00 +0100On the Influence of Riveting Process Parameters on Fatigue Life of Riveted Lap Joint
http://jacm.scu.ac.ir/article_14533_1889.html
In this paper, influence of riveting process parameters, namely, riveting force, sheet thickness, friction coefficient and clearance fit are investigated on residual stress field and fatigue life of single riveted lap joint of AA2024 type. According to the effect of riveting induced residual stresses on fatigue life of riveted lap joint, these parameters are optimized to maximize the residual stress field. For this purpose, finite element simulations are performed for various combinations of the parameters according to Taguchi design of experiments. Afterwards, the parameter combination that maximize the residual stress field and the most effective parameters are obtained. The joint with maximum residual stress field is considered to have a semi-elliptical crack emanating from the rivet hole as an initial defect. Stress intensity factors are calculated by implementing two approaches: First, formulation overview that considers the effect of residual stress field, geometry and secondary bending, and second, the finite element method. The fatigue life of the joint is estimated using the obtained stress intensity factors and Paris-Erdogan rule. Finally, good accordance is found between results of these two approaches.Tue, 31 Mar 2020 19:30:00 +0100Unsteady Hydromagnetic Flow of Eyring-Powell Nanofluid over an Inclined Permeable Stretching ...
http://jacm.scu.ac.ir/article_14580_1889.html
The present analysis deals with an unsteady magnetohydrodynamic flow of Eyring-Powell nanofluid over an inclined permeable stretching sheet. Effects of thermal radiation, Joule heating, and chemical reaction are considered. The effects of Brownian motion and thermophoresis on the flow over the permeable stretching sheet are discussed. Using Runge-Kutta fourth-order along with shooting technique, numerical and graphical results were obtained for the governing flow equations. The influence of various parameters on flow variables have been examined in detail. The results reveal that the temperature of the fluid enhanced with increasing Brownian and thermophoresis parameters. The increase of fluid velocity with the local Grashof number, the solutal Grashof number has been noticed. Further, the nanoparticles concentration decreased for a given increase in Brownian motion and chemical reaction parameters, while it increased with an increase in the thermophoresis parameter.Tue, 31 Mar 2020 19:30:00 +0100Numerical Simulation of Non-Newtonian Inelastic Flows in Channel based on Artificial ...
http://jacm.scu.ac.ir/article_14699_1889.html
In this study, inelastic constitutive modelling is considered for the simulation of shear-thinning fluids through a circular channel. Numerical solutions are presented for power-law inelastic model, considering axisymmetric Poiseuille flow through a channel. The numerical simulation of such fluid is performed by using the Galerkin finite element approach based on artificial compression method (AC-method). Usually, the Naiver-Stoke partial differential equations are used to describe fluid activity. These models consist of two partial differential equations; a continuity equation (mass conservation) and time-dependent conservation of momentum, which are maintained in the cylindrical coordinate system (axisymmetric) flow in current study. The effects of many factors such as Reynolds number (Re) and artificial compressibility parameter (ßac) are discussed in this study. In particular, this study confirms the effect of these parameters on the convergence level. To meet the method analysis, Poiseuille flow along a circular channel under an isothermal state is used as a simple test problem. This test is conducted by taking a circular section of the pipe. The Findings reveal that, there is a significant effect from the inelastic parameters upon the the velocity temporal convergence-rates of velocity, while for pressue, the change in convergence is modest. In addition, the rate of convergence is increased as the values of artificial compressibility parameter (ßac) are decreased.Tue, 31 Mar 2020 19:30:00 +0100Effect of Coating Materials on the Fatigue Behavior of Hip Implants: A Three-dimensional Finite ...
http://jacm.scu.ac.ir/article_14665_1889.html
This study aims to validate, using finite element analysis (FEA), the design concept by comparing the fatigue behavior of hip implant stems coated with composite (carbon/PEEK) and polymeric (PEEK) coating materials corresponding to different human activities: standing up, normal walking and climbing stairs under dynamic loadings to find out which of all these models have a better performance in the prosthesis-bone systems. A 3D finite element models of hip implants, femur, coating layers with polymeric (PEEK) and composite (carbon/PEEK) coating materials are created for FEA. The cyclic loads are applied on the prosthesis head. Fatigue life durations are calculated based on the Goodman mean-stress fatigue theory. The fatigue safety factor for the coated implant is increased more than 12.73% at least compared to the uncoated implant. The carbon/PEEK composite material with 0, +45, -45, and 90 degrees fiber orientation (configuration I) has the highest fatigue life and fatigue safety factor. The numerical result show that the carbon/PEEK composite material (configuration I) seems to be a good solution to increase the values of fatigue safety factor of coating layers due to highest fatigue life and fatigue safety factor. It distributes the applied load and transfers it to the bone, reducing stress-shielding effects and prolong the bone-prosthesis system life span.Tue, 31 Mar 2020 19:30:00 +0100Slip Effects on Ohmic Dissipative Non-Newtonian Fluid Flow in the Presence of Aligned Magnetic Field
http://jacm.scu.ac.ir/article_14453_1889.html
The present paper deals with the effects of Ohmic dissipative Casson fluid flow over a stretching sheet in the presence of aligned magnetic field. The present phenomenon also includes the interaction of thermal radiation and velocity slip. The governing boundary layer equations are transformed into a set of ordinary differential equations using the similarity transformations. The dimensionless velocity and temperature profiles are solved analytically using hypergeometric function and numerically by using fourth order Runge-Kutta method with shooting technique. It is noted that the increasing values of Eckert number increases the temperature profile and decreases the local Nusselt number.Tue, 31 Mar 2020 19:30:00 +0100Mesoscopic Simulation of Forced Convective Heat Transfer of Carreau-Yasuda Fluid Flow over an ...
http://jacm.scu.ac.ir/article_14545_1889.html
In the current study, non-Newtonian flow pattern and heat transfer in an enclosure containing a tilted square are examined. In order to numerically simulate the problem, the mesoscopic lattice Boltzmann method is utilized. The non-Newtonian Carreau-Yasuda model is employed. It is able to adequately handle the shear-thinning case. The simulation results of flow and heat transfer have been successfully verified with the previous studies. Several parameters such as Nusselt number, Drag coefficient, and Carreau number are investigated in details. Considering the temperature-dependent viscosity, it is seen that with increasing thetemperature-thinning index, the drag coefficient increases, but the Nusselt number decreases. By rotating the square obstacle, the results display that increasing the angle of inclination from zero to 45 degrees, increases both the drag coefficient and the Nusselt number. Also, the highest rate of heat transfer occur at the angle of 45 degrees (diamond); however it has a negative impact on the Drag coefficient.Tue, 31 Mar 2020 19:30:00 +0100A Modified Energy Balance Method to Obtain Higher-order Approximations to the Oscillators with ...
http://jacm.scu.ac.ir/article_14667_1889.html
This article analyzes a strongly nonlinear oscillator with cubic and harmonic restoring force and proposes an efficient analytical technique based on the modified energy balance method (MEBM). The proposed method incorporates higher-order approximations. After applying the proposed MEBM, a set of complicated higher-order nonlinear algebraic equations are obtained. Higher-order nonlinear algebraic equations are cumbersome to investigate especially in the case of a large initial oscillation amplitude. This limitation is overcome in the proposed method by using the iterative procedure based on the homotopy perturbation method. The approximated results agree well with the numerically obtained exact solutions. These third-order approximate solutions are found to be almost the same as exact solutions, which cannot be found using the existing energy balance method. Highly accurate result and simple solution procedure are advantages of this proposed method, which could be applied to other nonlinear oscillatory problems arising in nonlinear science and engineering.Tue, 31 Mar 2020 19:30:00 +0100Experimental Investigation and Optimizing Geometrical Characteristics and Surface Quality in ...
http://jacm.scu.ac.ir/article_14643_1889.html
The aim of this paper is to investigate and optimize surface quality and geometrical characteristics in drilling process of AISI H13 steel, because they are critical items for precision manufacturing. After conducting the experiments, two regression models are developed to extensively evaluate the effect of drilling parameters on process outputs. After that, evolutionary multi-objective optimization algorithm is employed to find the optimal drilling conditions. Non-dominated Sorting Genetic Algorithm (NSGA-ІІ) is developed and regression functions are taken into account as objective functions of algorithm to simultaneously optimize the surface roughness and deviation of circularity. The optimization results are successfully in agreement with experimental findings and finally the set of optimal drilling conditions is reported that can be selected by process engineer according to the priority and application. It is shown that, an increase in Cutting speed and liquid coolant intensity decreases the surface quality, while higher depth of cut, tool diameter and reed rate improve it. It is also found that tool diameter and depth of cut are the most effective input parameters on deviation of circularity. Finally, it can be concluded that, the implemented approach in this research provides an efficient method for other manufacturing processes to increase the performance and reduction of production costs.Tue, 31 Mar 2020 19:30:00 +0100A Parameter Uniform Numerical Scheme for Singularly Perturbed Differential-difference Equations ...
http://jacm.scu.ac.ir/article_14461_1889.html
In this paper, we consider a second-order singularly perturbed differential-difference equations with mixed delay and advance parameters. At first, we approximate the model problem by an upwind finite difference scheme on a Shishkin mesh. We know that the upwind scheme is stable and its solution is oscillation free, but it gives lower order of accuracy. So, to increase the convergence, we propose a hybrid finite difference scheme, in which we use the cubic spline difference method in the fine mesh regions and a midpoint upwind scheme in the coarse mesh regions. We establish a theoretical parameter uniform bound in the discrete maximum norm. To check the efficiency of the proposed methods, we consider test problems with delay, advance and the mixed parameters and the results are in agreement with our theoretical findings.Tue, 31 Mar 2020 19:30:00 +0100An Analytical Approach of Nonlinear Thermo-mechanical Buckling of Functionally Graded ...
http://jacm.scu.ac.ir/article_14642_1889.html
This paper deals with an analytical approach to predict the nonlinear buckling behavior of functionally graded graphene-reinforced composite laminated cylindrical shells under axial compressive load surrounded by Pasternak’s elastic foundation in a thermal environment. Piece-wise functionally graded graphene-reinforced, composite layers are sorted with different types of graphene distribution. The governing equations are established by using Donnell’s shell theory with von Kármán nonlinearity terms and three-term solution of deflection is chosen for modeling the uniform deflection of pre-buckling state, linear and nonlinear deflection of post-buckling state. Galerkin method is applied to determine the critical axial compressive buckling load expression, post-buckling load-deflection and load-end shortening relations of the shell. The effects of environment temperature, foundation, geometrical properties, and graphene distribution on buckling behavior of shell, are numerically evaluated.Tue, 31 Mar 2020 19:30:00 +0100Finite Element Analysis of Low Velocity Impact on Carbon Fibers/Carbon Nanotubes Reinforced ...
http://jacm.scu.ac.ir/article_14510_0.html
An effort is made to gain insight on the effect of carbon nanotubes (CNTs) on the impact response of carbon fiber reinforced composites (CFRs) under low velocity impact. Certain amount of CNTs could lead improvements in mechanical properties of composites. In the present investigation, ABAQUS/Explicit finite element code (FEM) is employed to investigate various damages modes of nano composites including matrix cracking, fiber damage and delamination by employing Hashin’s criterion and cohesive zone modeling. The obtained results for 0, 0.5, 1, 2 and 4% CNTs demonstrate that by including CNTs in composite plates, damage could be reduced. However, adding further CNTs causes sudden reduction of impact tolerance capability of the composite plates, particularly, damage due to delamination.Wed, 19 Jun 2019 19:30:00 +0100Simple Two Variable Refined Theory for Shear Deformable Isotropic Rectangular Beams
http://jacm.scu.ac.ir/article_14620_0.html
In this paper, a displacement-based, variationally consistent, two variable refined theory for shear deformable beams is presented. The beam is assumed to be of linearly elastic, homogeneous, isotropic material and has a uniform rectangular cross-section. In this theory, the beam axial displacement and beam transverse displacement consist of bending components and shearing components. The assumed displacement field of this theory is such that, bending components do not take part in the cross-sectional shearing force, and shearing components do not take part in the cross-sectional bending moment. This theory utilizes linear strain-displacement relations. The displacement functions give rise to the beam transverse shear strain (and hence to the beam transverse shear stress) which varies quadratically through the beam thickness and maintains transverse shear stress-free beam surface conditions. Hence the shear correction factor is not required. Hamilton’s principle is utilized to derive governing differential equations and variationally consistent boundary conditions. This theory involves only two governing differential equations of fourth-order. These governing equations are only inertially coupled for the case of dynamics and are decoupled for the case of statics. This theory is simple and has a strong resemblance with the Bernoulli-Euler beam theory. To demonstrate the efficacy of the present theory, illustrative examples pertain to the static bending and free vibrations of shear deformable isotropic rectangular beams are presented.Fri, 26 Jul 2019 19:30:00 +0100Vibration Analysis of Different Types of Porous FG Conical Sandwich Shells in Various Thermal ...
http://jacm.scu.ac.ir/article_14572_0.html
Vibration behavior of different types of porous functionally graded (FG) conical sandwich shells are investigated based on a modified high order sandwich shells theory for the first time. Sandwich shell includes FG face sheets covering a homogeneous core and the second one includes homogeneous face sheets and a FG core. Power law rule modified by considering two types of porosity distributions is used to model the functionally graded materials. All materials are temperature dependent and uniform, linear and nonlinear temperature distributions are used to model the effect of the temperature variation in the sandwiches. Governing equations are obtained by the Hamilton's energy principle and solved with Galerkin method. To verify the results, they are compared with ones achieved by finite element method obtained by Abaqus software for special cases with the results in literatures.Wed, 03 Jul 2019 19:30:00 +0100Heat Transfer Analysis of Nanofluid Flow with Porous Medium through Jeffery Hamel ...
http://jacm.scu.ac.ir/article_14616_0.html
In this paper, flow and heat transfer of nanofluid through a converging or diverging channel with porous medium is investigated. The fluid constantly flows under the effect of magnetic field through the channel. The diverging/converging fluid motion is modeled using the momentum and energy equations. The influence of some parameters such as opening channel angle, Reynolds number and Darcy’s number when the nanofluid flows through the non-parallel plates are studied. It is seen that high Reynolds number enhances the fluid viscosity while decreases velocity. Similarly, heat transfer reduces at high Darcy’s number owing to decreased flow consequently internal friction reduces. The obtained results in comparison with the similar studies in the literatures show satisfactory agreement.Mon, 22 Jul 2019 19:30:00 +0100On Green and Naghdi Thermoelasticity Model without Energy Dissipation with Higher Order Time ...
http://jacm.scu.ac.ir/article_14668_0.html
In the present work, a modified model of heat conduction including higher order of time derivative is derived by extending Green and Naghdi theory without energy dissipation. We introduce two phase lag times to include the thermal displacement gradient and the heat flux in the heat conduction and depict microscopic responses more precisely. The constructed model is applied to study thermoelastic waves in a homogeneous and isotropic perfect conducting unbounded solid body containing a spherical cavity. We use the Laplace transform method to analyze the problem. The solutions for the field functions are obtained numerically using the numerical Laplace inversion technique. The results are analyzed in different tables and graphs and compared with those obtained earlier in the contexts of some other theories of thermoelasticity.Wed, 21 Aug 2019 19:30:00 +0100Fluid Flow and Heat Transfer over Staggered ꞌ+ꞌ Shaped Obstacles
http://jacm.scu.ac.ir/article_13989_0.html
The inclusion of complex obstacles within solar channels is the aim of this article. Two obstacles of the form ꞌ+ꞌ interlaced within a two-dimensional and rectangular channel are the subject of our study. The fluid is Newtonian, turbulent, incompressible and has constant properties. The Reynolds number varies from 12,000 to 32,000 with a constant temperature along the upper surface of the channel. The thermal and dynamic analysis of the channel's internal structure has been carefully processed. Different fields of speed and heat, with various profiles of frictions and heat exchange coefficients, have been included in this research. Future work will involve more complex geometries and using nanofluids to assess the optimum conditions for heat transfer enhancements.Fri, 14 Dec 2018 20:30:00 +0100Non-similar solutions of MHD mixed convection over an exponentially stretching surface: ...
http://jacm.scu.ac.ir/article_14133_0.html
In this paper, an analysis of MHD mixed convection over an exponentially stretchingsurface in the presence of a non-uniform heat source/sink and suction/injection is presented. Thegoverning boundary layer equations are transformed into a set of non-dimensional equations byusing a group of non-similar transformations. The resulting highly non-linear coupled partialdifferential equations are solved by using the implicit finite difference method combined with thequasilinearization technique. Numerical results for the velocity, temperature and concentrationprofiles, as well as the skin friction coefficient, wall heat transfer and mass transfer rates arecomputed and presented graphically for various parameters.Mon, 18 Feb 2019 20:30:00 +0100Numerical Scrutinization of Three Dimensional Casson-Carreau Nano Fluid Flow
http://jacm.scu.ac.ir/article_14411_0.html
This study presents the computational analysis of three dimensional Casson and Carreau nanofluid flow concerning the convective conditions. To do so, the flow equations are modified to nonlinear system of ODEs after using appropriate self-similarity functions. The solution for the modified system is evaluated by numerical techniques. The results show the impacts of involving variables on flow characteristics and the outcomes of the friction factors are evaluated as well. In this study, the outcomes to local Nusselt number and Sherwood numbers are evaluated. Favourable comparison is performed with previously available outcomes. The achieved results are similar to solutions obtained by other researchers. The results are presented for flow characteristics in the case of Casson and Carreau fluids. Velocities are reduced for the growing values of permeability and velocity slip parameters in case of Casson and Carreau nanofluids. Temperature field enhances with the hike in the estimations of thermophoresis parameter and the thermal Biot number in case of Casson and Carreau nanofluids. Enhancing values of velocity slip parameter results in decrease in the skin friction coefficients and the rate of heat transfer, and rise in the rate of mass transfer in case of Casson and Carreau nanofluids.Sat, 20 Jul 2019 19:30:00 +0100Prediction of Entrance Length for Magnetohydrodynamics Channels Flow using Numerical simulation ...
http://jacm.scu.ac.ir/article_14420_0.html
This paper focuses on using the numerical finite volume method (FVM) and artificial neural network (ANN) in order to propose a correlation for computing the entrance length of laminar magnetohydrodynamics (MHD) channels flow. In the first step, for different values of the Reynolds (Re) and Hartmann (Ha) numbers (600<ReL increases.Tue, 14 May 2019 19:30:00 +0100A Hybrid Particle Swarm Optimization and Genetic Algorithm for Truss Structures with Discrete ...
http://jacm.scu.ac.ir/article_14429_0.html
A new hybrid algorithm of Particle Swarm Optimization and Genetic Algorithm (PSOGA) is presented to get the optimum design of truss structures with discrete design variables. The objective function chosen in this paper is the total weight of the truss structure, which depends on upper and lower bounds in the form of stress and displacement limits. The Particle Swarm Optimization basically modeled the social behavior of birds on the basis of the fact that Individual birds exchange information about their position, velocity, fitness, and on the basis that the behavior of the flock is then influenced to increase the probability of migration to other regions with high fitness. One of the problems of PSO is that it is easily trapped at the local point due to its non-uniform movement. The present study uses the mutation, random selection, and reproduction to reach the best genetic algorithm with the operators of natural genetics. Therefore, only identical chromosomes or particles can be converged. In other words, PSO and GA algorithm goes from one point in the search space to another point, interacting with each other. In this way, this helps them to find the optimum design by means of deterministic and probabilistic rules. The present study merged the two algorithms together in order to design several benchmark truss structures, and then the results of the new algorithm compared to those of other evolutionary optimization methods.Thu, 16 May 2019 19:30:00 +0100Effect of Tool Shoulder and Pin Cone Angles in Friction Stir Welding using Non-circular Tool Pin
http://jacm.scu.ac.ir/article_14534_0.html
In friction stir welding frictional heat is generated by the rotating tool, sliding over the stationary plate along the weld centre. Tool being the only source of heat producing member, its geometrical design influences the heat generation rate. In this present work, effects of variation in tool shoulder and tool pin taper angles on thermal history during joining are analysed. Tools with triangular and hexagonal tool pins are used to understand the influence of tool pin shape on process temperature. An analytical heat input model is developed for tools with non-circular tool pins and a comparative study is carried out between the hexagonal and triangular tool pins on temperature distribution using a three dimensional Matlab model. Proposed model is validated through experimental analysis. Apart from this, regression model based comparative study is carried out on the variation in temperature response to the change in tool pin shape, tool shoulder and tool pin taper angle.Sat, 22 Jun 2019 19:30:00 +0100On the Six Node Hexagon Elements for Continuum Topology Optimization of Plates Carrying in ...
http://jacm.scu.ac.ir/article_14535_0.html
The need of polygonal elements to represent the domain is gaining interest among structural engineers. The objective is to perform static analysis and topology optimization of a given continuum domain using the rational fraction type shape functions of six node hexagonal elements. In this paper, the main focus is to perform the topology optimization of two-dimensional plate structures using Evolutionary Swarm Intelligence Firefly Algorithms (ESIFA) and three-dimensional shell structures using optimality criteria. The optimization of plates carrying in plane loading is performed with minimum weight as objective. Two different types of shell structures are optimized using maximum strain energy as criteria. The optimal distribution of the material in the design domain obtained using six node hexagon elements is compared with the optimal distribution of material obtained using quadrilateral elements. A few problems from the literature have been solved and this study has proved that hexagon element gives better results over traditional quadrilateral elements.Sun, 23 Jun 2019 19:30:00 +0100Impact of Blood Vessel Wall Flexibility on the Temperature and Concentration Dispersion
http://jacm.scu.ac.ir/article_14536_0.html
The analysis of solute and thermal dispersion in pulsatile flow through the stenotic tapered blood vessel is presented. The present problem is an extension of the work done by Ramana et al. who considered the time-invariant arterial wall. In the present model, the flexible nature of the arterial wall through the obstruction (called stenosis) is considered and it is achieved with the help of period trigonometric function. In the present study, the impact of the time-dependent arterial wall on the blood flow dynamics is discussed in details. The rheology of the blood is modeled as a couple stress fluid. The proposed fluid model is the isothermal inclusion of temperature-sensitive drug coated Titanium dioxide Nano-particles in the couple stress fluid for examining the concentration and temperature dispersion. The effects of the catheter and permeability of the stenosis are considered in the model. Care has been taken to model the thermo-physical properties of the fluid with the immersed nanoparticle, e.g., TiO2, Ag and Cu. The modeled non-linear and coupled equations are solved by using the Homotopy Perturbation Method. The temperature and concentration dispersion effects are in the flexible stenotic arterial vessel under the pulsatile physiological pressure gradient are studied and reported in details. The alterations in the axial velocity, resistance to the flow, and wall shear stress are studied and found out that the high intense vortex regions are identified in the stenotic region. The model has direct applications in the pharmaceutical industry in design and developing the drug to treat stenotic conditions.Wed, 26 Jun 2019 19:30:00 +0100Sealing Performance of the End Fitting of a Marine Unbonded Flexible Pipe under Pressure Penetration
http://jacm.scu.ac.ir/article_14570_0.html
The sealing performance of end fittings is very important for offshore oil and gas pipelines. To investigate the sealing behavior of a ring-shaped wedge seal, global and local numerical models of the ring–pipe interaction have been developed based on the finite-element method. First, the sealing process of the ring under pressure is simulated. Second, a criterion for the penetration of fluid pressure is applied in these models to assess how the sealing capacity changes along the contact surface. Finally, the contact magnitude of interference and the shape of the sawtooth heaves on the sealing ring are predicted and compared. The results show an interesting concentration of von Mises stress in the sealing ring and also that the peak contact pressure appears in the sealing zone. However, the penetration of fluid pressure has obvious effects on the distributions of von Mises stress and contact pressure. The best sealing performance is when the axial displacement of the sealing ring is 1.4 mm and the contact magnitude of interference is 0.3 mm. Given the sawtooth heave of sealing ring, semicircular heave gives the better sealing capacity compared with trapezoidal heave.Mon, 01 Jul 2019 19:30:00 +0100Multivariate Jeffrey Fluid Flow past a Vertical Plate through Porous Medium
http://jacm.scu.ac.ir/article_14579_0.html
An analysis is suggested to study the impact of Hall currents in Jeffrey fluid which is chemically reactive through a porous medium limited by a semi-infinite vertical permeable plate within the existence of heat generation. An evenly distributed magnetic field turns vertically on the porous surface which absorbs the Jeffrey fluid with a changed suction velocity with time. The analytical expressions are solved by means of three terms harmonic and non-harmonic functions. Statistical calculations are carried out for the point of resultant outcomes which are shown graphically and the impacts of the parameters velocity, temperature and concentration are listed. In addition, the results of skin-friction coefficient (τ), Nusselt number (Nu) and Sherwood number (Sh) are taken in to consideration. It is revealed that the impact of the Hall parameter on the channel velocities and skin friction coefficient is subjected to the estimation of the wall suction parameter.Tue, 09 Jul 2019 19:30:00 +0100Designing and Creating a Mouse Using Nature-Inspired Shapes
http://jacm.scu.ac.ir/article_14621_0.html
Human beings have always made their tools and instruments they need using patterns in nature. Mimicking nature has become the foundation of a new science called Biomimetics. In the present article, multiple forms and levels in nature were utilized to design and create a mouse. The rivers are a good source for choosing the shape of a mouse with lots of stones abraded through the centuries which also have smooth surfaces. In this research, a significant number of stones fitted to hand size were collected and then the best ones were scanned by an optical scanner. The point cloud model obtained was used to design and create the mouse and determine the geometric parameters of the mouse. After extracting the 3D model of the point cloud using a rapid prototyping technique with the Fused Deposition Modeling (FDM) method, some mouse models were designed ambidextrously for left-handed and right-handed people. Considering the results of the mouse evaluation by 30 people who were provided with the mouse, it can be concluded that the created mouse provided a high rate of satisfaction.Sat, 27 Jul 2019 19:30:00 +0100A FEM Multiscale Homogenization Procedure using Nanoindentation for High Performance Concrete
http://jacm.scu.ac.ir/article_14634_0.html
This paper aims to develop a numerical multiscale homogenization method for prediction of elasto-viscoplastic properties of a high performance concrete (HPC). The homogenization procedure is separated into two-levels according to the microstructure of the HPC: the mortar or matrix level and the concrete level. The elasto-viscoplastic behavior of individual microstructural phases of the matrix are identified from nanoindentation data using an inverse identification method. The micromechanical results are then used as input parameters for numerical elasto-viscoplastic homogenization at microscale. The mortar level is analyzed with numerical homogenization by using the finite element simulation to predict the overall elasto-viscoplastic properties of HPC. The results are compared with macroscopic experimental and analytical results from the literature showing a good agreement.Mon, 29 Jul 2019 19:30:00 +0100Numerical simulation of unsteady flow toward a stretching/shrinking sheet in porous medium ...
http://jacm.scu.ac.ir/article_14641_0.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.Sat, 03 Aug 2019 19:30:00 +0100Multiple Solutions for Slip Effects on Dissipative Magneto-Nanofluid Transport Phenomena in ...
http://jacm.scu.ac.ir/article_14645_0.html
The present paper considers a numerical investigation of transport phenomena in electrically-conducting nanofluid flow within porous bed utilizing Buongiorno’s transport model and Runge-Kutta-Fehlberg fourth-fifth order method. Induced flow by non-isothermal stretching/shrinking sheet along with magnetic field impact, dissipation effect and slip conditions at the surface are also included. The numerical results show the existence of two branches of the solution for a selected range of the governing parameters. The physical significance of both branches of solutions is ensured by performing a stability analysis in which a linearized eigenvalue problem is solved. The multiple regression analysis with help of MALTAB LinearModel.fit package has also been conducted to estimate the dependency of the parameters on Nusselt number.Thu, 08 Aug 2019 19:30:00 +0100Emotional Learning Based Intelligent Controller for MIMO Peripheral Milling Process
http://jacm.scu.ac.ir/article_14664_0.html
During the milling process, one of the most important factors in reducing tool life expectancy and quality of workpiece is the chattering phenomenon due to self-excitation. The milling process is considered as a MIMO strongly coupled nonlinear plant with time delay terms in cutting forces. We stabilize the plant using two independent Emotional Learning-based Intelligent Controller (ELIC) in parallel. Control inputs are considered as forces Ux and Uy in two directions x and y, which are applied by the piezoelectrics. The ELIC consists of three elements; Critic, TSK controller and the learning element. The results of the ELIC have been compared with a Sliding Mode Controller (SMC). The simulation for the nominal plant shows better performance of the ELIC in IAE and ITSE values at least 86% in the x-direction and 79% in the y-direction. Similar simulation for an uncertain plant also shows an improvement of at least 89% in the x-direction and 97% in the y-direction.Wed, 14 Aug 2019 19:30:00 +0100Dynamic Analysis of the Biomechanical Model of Head Load Impact Using Differential Transform Method
http://jacm.scu.ac.ir/article_14666_0.html
The dynamic analysis of the biomechanical model of the head load impact using Differential Transform Method is presented in this paper. In many parts of the world, the problem of traumatic brain injuries (TBI) which has led to neurodegenerative dementing disorders and diseases as a result of head load impact from sporting activities, accidents involving the head, etc. have serious effects on humanity. The head load impact and its control have been modeled as a rigid linkage head-neck manipulator. This rigid link manipulator is governed by a system of nonlinear ordinary differential matrix equations with three degrees of freedom which requires special techniques for its solution. The system of equations was solved using Differential Transform Method (DTM) and the results were compared with results obtained in earlier studies and validated with the fourth-order Runge-Kutta numerical method (RK4). Good agreements are reached in all these results. From the model, the effects of head loads, head mass, neck mass, upper and lower linkage lengths, head and neck moments of inertia were investigated. As the head loads increased, there were increases in both axial and angular displacement of the head motion and the neck region. The study provides a theoretical basis for the design and understanding of the effects of head load carriage on vital organs that are susceptible to pains, damages, and even failure.Tue, 20 Aug 2019 19:30:00 +0100Comprehensive Investigating on the Aerodynamic Influences of the Wheel Contact Patch
http://jacm.scu.ac.ir/article_14700_0.html
The wheel contact patch is an important part of the real car model which cannot be neglected in the numerical simulations. The aerodynamic influences of wheel contact patch have not studied enough to show its impact on the aerodynamics coefficients. This paper investigates the influence of the wheel contact patch on the global car aerodynamics by computational fluid dynamics. Two main aspects of the problem are contact step and patch shape. There are three important parameters: step height, cut angle and tire tread shape that are taken into consideration. Experimental data are also applied for validations of the simulation results. The obtained results show that the step height may not significantly affect the global flow field. But cut angle and tire tread shape can significantly change the aerodynamics coefficients. When the cut angle increases, the flow separations on the two sides of the front wheel patch will be suppressed successively, which generates two critical points and a sudden drag decrease is achieved. Besides, the tiny differences on tread shape can effectively change the flow rate of underbody and make a huge drag discrepancy in the results. In conclusion, the cut angle and tire tread shape must be considered as two significant parameters and be dealt with carefully in the aerodynamic applications of automotive engineering.Wed, 28 Aug 2019 19:30:00 +0100Modelling of Love Waves in Fluid Saturated Porous Viscoelastic Medium resting over an ...
http://jacm.scu.ac.ir/article_14702_0.html
The present article is devoted to a theoretical study on Love wave vibration in a pre-stressed fluid-saturated anisotropic porous viscoelastic medium embedded over an inhomogeneous isotropic half-space influenced by gravity. The expression of dispersion has been achieved with the help of mathematical tools such as variable separable method and Whittaker’s function’s expansion under certain boundary conditions. After that, the obtained result has been coincided with the pre-established classical equation of Love wave, as shown in the section of particular case and validation. The substantial influence of various affecting factors like gravity, initial stress, porosity, viscosity and inhomogeneity on dispersion curves of Love wave has been investigated extensively by means of graphical depictions and discussions accomplished by numerical results.Thu, 29 Aug 2019 19:30:00 +0100Experimental and numerical buckling analysis of carbon fiber composite lattice conical ...
http://jacm.scu.ac.ir/article_14704_0.html
In this research, the numerical and experimental analysis of the composite lattice conical structure made of carbon has been investigated. This research investigates the buckling stability of the structure before and after a lateral impact. In the experimental analysis, the composite lattice conical structures made of carbon were constructed with the winding method and using elastic molds and metal mandrel. In order to investigate the buckling stability of the structures before each lateral impact, each of the structures was subjected to be compressive- axial loading. Then, the other structures first were subjected under axial-compressive loading and in the next step, a compressive loading was applied to determine the effect of the impact on the compressive strength of the damaged structures. In the numerical analysis, the ABAQUS finite-element software was used for modeling and performing the mentioned analysis. In the end, the results from both methods used in this study were compared, and the results from these comparisons showed that effect of the lateral impact to each of the structures causes how many the reduction in the buckling strength, so that, it could be considered during the design of the applied structures. On the other hand, the low difference between the numerical and experimental simulations of this research shows that experimental and numerical methods can be used to analyze structures of this type with different geometric characteristics and material, and also to save time and cost.Sat, 31 Aug 2019 19:30:00 +0100An Efficient Implementation of Phase Field Method with Explicit Time Integration
http://jacm.scu.ac.ir/article_14725_0.html
The phase field method integrates the Griffith theory and damage mechanics approach to predict crack initiation, propagation, and branching within one framework. No crack tracking topology is needed, and complex crack shapes can be captures without user intervention. In this paper, a detailed description of how the phase field method is implemented with explicit dynamics into LS-DYNA is provided. The displacement field and the damage field are solved in a staggered approach and the phase field equation is solved every Nth time step (N is refered to as calculation cycle) to save computational time. An N value smaller than 1/400 of the total time step numbers is suggested. Several simulations are presented to demonstrate the feasibility of this solving scheme.Thu, 05 Sep 2019 19:30:00 +0100Optimization of the prismatic core sandwich panel under buckling load and yield stress ...
http://jacm.scu.ac.ir/article_14740_0.html
In this study, weight optimization of the prismatic core sandwich panel under transverse and longitudinal loadings has been independently investigated. To solve the optimization problems corresponding to the mentioned loadings, a new Improved Constrained Differential Evolution (ICDE) algorithm based on the multi-objective constraint handling method has been used. The Constrains of the problems are buckling load and yield stress. By comparing the results of the ICDE with those obtained by the other evolutionary algorithms based on the penalty function method in the previous studies, it can be seen that the results of the transverse loading obtained in this study are equal to those of the previous works, but the results of the ICDE in the longitudinal loading are better. In addition to its better results and ease of implementation, another advantage of ICDE is that there is no need to the process of trial and error to fine tuning of the penalty function parameters. It can be observed that for the both types of loading, values of the panel height, the face and core member thickness in addition to the weight index are increased by increasing the load index to avoid yielding and buckling of the panel. But in a constant value of the load index, by increasing the core corrugate number the weight index has a lowering behavior in the transverse loading and a rising behavior in the longitudinal loading.Thu, 12 Sep 2019 19:30:00 +0100Stability Assessment of the Flexible System using Redundancy
http://jacm.scu.ac.ir/article_14741_0.html
In this study, dynamic behavior of a mooring line in a floating system is analyzed by probability approaches. In dynamics, most researches have shown the system model and environments by mathematical expression. We called this process as the forward dynamics. However, there is a limit to define the exact environments because of uncertainty. To consider uncertainty, we introduce the redundancy in flexible system, mooring line. For verifying the effectiveness and stability of the mooring line, criterion of axial breaking load of the mooring line is applied to joint reaction forces according to the various path of the mooring line. To cover the limits for defining the non-linearity of the environments, various responses of the mooring line along the redundancy that is used in Robotics, are derived by probability distribution. By using the Newton-Euler formulation, the inverse kinematics and the linear acceleration theorem to get joint displacements, velocities and accelerations, the joint reaction forces and moments are calculated and probability distribution of the mooring about stability and compatibility is investigated. Lastly, we simulate the flexible systems in various null motions, calculated each joint torque and force, and evaluated failure probabilities using the Monte-Carlo method.Thu, 12 Sep 2019 19:30:00 +0100Thermal Buckling Analysis of Functionally Graded Euler-Bernoulli Beams with ...
http://jacm.scu.ac.ir/article_14742_0.html
Thermal buckling behavior of functionally graded Euler-Bernoulli beams in thermal conditions is investigated analytically. The beam with material and thermal properties dependent on the temperature and position is considered. Based on the transformed-section method, the functionally graded beam is considered as an equivalent homogeneous Euler-Bernoulli beam with an effective bending rigidity under an eccentric thermal load. Then, the thermal elastic buckling equation associated with the bending deflection about the neutral axis is established. The easily usable closed-form solutions for the critical thermal buckling temperature of functionally graded beams under uniform and non-linear temperature rise are obtained and used to calculate the thermal buckling temperature. Some results are evaluated and compared with those by other investigators to validate the accuracy of the presented method. The effects of material compositions, temperature-dependent material properties, slenderness ratios and restraint conditions on thermal buckling behaviors are discussed. It is believed that the proposed model provides engineers and designers an easy and useful method to investigate the effects of various parameters affecting the thermal buckling characteristics of functionally graded beams.Thu, 12 Sep 2019 19:30:00 +0100Mechanics of 2D Elastic Stress Waves Propagation Impacted by Concentrated Point Source ...
http://jacm.scu.ac.ir/article_14748_0.html
Green’s function, an analytical approach in inhomogeneous linear differential equations, is the impulse response, which is applied for deriving the wave equation solution in composite materials mediums. This paper investigates the study of SH wave’s transmission influenced by concentrated point source disturbance in piezomagnetic material resting over heterogeneous half-space. Green function approach is used to solve differential equation and obtain the dispersion relation in determinant form and match with existing classical Love wave equation for the authenticity for the article. The properties of SH wave throughout the considered framework and their state of relying on varied geometrical and physical parameters are scrutinized. The simulated outcomes of disparate physical quantities viz., dimensionless phase velocity, elastic parameter, group velocity, initial stress, piezomagnetic/heterogeneity parameter and stress distribution of SH wave in the considered structure are investigated and used to regulate the behavior of dispersion characteristics of smart material waveguides.Fri, 13 Sep 2019 19:30:00 +0100Three dimensional non-linear radiative nanofluid flow over a Riga plate
http://jacm.scu.ac.ir/article_14751_0.html
Numerous techniques in designing zones happen at high temperature and functions under high temperature are in a way that involves with non-linear radiation. In weakly conducting ﬂuids however, the currents induced by an external magnetic ﬁeld alone are too small, and an external electric ﬁeld must be applied to achieve an efﬁcient ﬂow control. Gailitis and Lielausis, deviced Riga plate to generate a crossed electric and magnetic ﬁelds which can produce a wall parallel Lorentz force in order to control the ﬂuid ﬂow. It acts as an efﬁcient agent to reduce the skin friction. So, in this paper, we start the numerical investigation on the three-dimensional flow of nanofluids with the inclusion of non-linear radiation past a Riga plate. Water (H_2 O) and Sodium Alginate (NaC6H9O7) are the base fluids, whereas Magnetite (Fe_3 O_4) and Aluminium oxide (Al2O3) are the nanoparticles. The mathematical formulation for Sodium Alginate base fluid is separated through the Casson model. Suitable transformations on governing partial differential equations yield strong non-linear ordinary differential equations. Numerical solutions for the renewed system are constructed by fourth-order Runge-Kutta method with shooting technique. Various deductions for flow and heat transfer attributes are sketched and discussed for various physical parameters. Furthermore, the similarities with existing results were found for the physical quantities of interest. It was discovered, that the temperature ratio parameter and the radiation parameter enhance the rate of heat transport. Further the NaC6H9O7- Al2O3 nanofluid improves the heat transfer rate. Likewise, H2O-Fe3O4 nanofluid stimulates the local skin friction coefficients.Sat, 14 Sep 2019 19:30:00 +0100Experimental Study of the Heat Transfer Enhancement in Concentric Tubes With Spherical and ...
http://jacm.scu.ac.ir/article_14754_0.html
In the current research project, the thermal performance of a series of newly designed mixers has been investigated. Each mixer has two concentric cylinders comprising two annular slot flow channels around a solid cylindrical rod at the center. In each mixer, the first cylinder around the central solid rod has either spherical or pyramidal protrusions throughout the outer surface. It has been observed that with varying mass flow rate of cold and hot water (1 kg/m3-sec to 5 kg/m3-sec), 17% increase in rate of heat transfer for cold water & 73% for hot water has been observed with a variation in mass flow rate of 1-3 kg/m3-sec with all combination of angles of holes in spherical protrusions. In the case of pyramidal protrusions, the rate of heat transfer has been raised from 16% for cold water & 88% for hot water at varying a mass flow rate of 1-3 kg/m3-sec in all combinations of angles of the top vortex in each protrusion. The effect of imparting the centrifugal force has raised the rates of heat transfer in the range of 24-36% at varying rpm from 60-180 rpm of the central cylinder, with the highest with 120 rpm. A comparison of the heat transfer rates reveals that with increasing the mass flow rates, rpm, angle of the holes in spherical protrusions and angle of the traversed angle at the top corner of each pyramidal protrusion didn’t contribute linearly in terms of rising in the rate of heat transfer.Sun, 15 Sep 2019 19:30:00 +0100Using the Finite Element Analysis Method to Study the 3-point Bending Test for the ...
http://jacm.scu.ac.ir/article_14755_0.html
An elastic finite element analysis was conducted to evaluate the stress distribution in the initiation zone of the adhesive rupture during the 3-point bending test. This test is used to measure the adherence between a polyepoxy adhesive and aluminum alloy with different surface treatments. The purpose is to compare, in the high stress concentration areas, the stress fields calculated using finite element method with the experimental data obtained in different configurations. Focusing on the load level at crack initiation, on the localization and the size of adhesive failure initiation, a local criterion for adhesive fracture is proposed based on the value of the stress normal to the interface.Sun, 15 Sep 2019 19:30:00 +0100Traveling wave solutions of 3D fractionalized MHD Newtonian fluid in porous medium with heat ...
http://jacm.scu.ac.ir/article_14757_0.html
In the present paper, we get exact solutions of Magnetohydrodynamic (MHD) of the fractionalized three-dimensional flow of Newtonian fluid with porous and heat transfer through traveling wave parameter. The governing equations are produced dependent on established Navier-stokes equations which can be diminished to ordinary differential equation by wave parameter ξ=ax+by+nz+ (Ut^α)/Γ(1-α) . The new exact solutions are established for three various cases. In special cases the solution for Newtonian fluid with and without MHD and porous effects can also be found from general solution by putting M,ϕ →0 and solutions for simple Newtonian fluid can also be obtained by putting α→1 in general solutions. Finally, the effect of the parameter of interest on the stream motion, as well as difference among the Newtonian fluids is also examined by 2D and 3D graphical interpretations.Tue, 17 Sep 2019 19:30:00 +0100Magnetohydrodynamics Fluid Flow and Heat Transfer over a Permeable Shrinking Sheet with Joule ...
http://jacm.scu.ac.ir/article_14759_0.html
A laminar, two dimensional, steady boundary layer Newtonian conducting fluid flow passes over a permeable shrinking sheet in the presence of a uniform magnetic field is investigated. The governing equations have converted to ordinary nonlinear differential equations (ODE) by using appropriate similarity transformations. The main idea is to transform ODE with infinite boundary condition into other sets of variables in a way that infinite boundary condition becomes a finite boundary condition. The effects of physical parameters affecting the velocity and temperature are shown. The results show that with increasing of the magnetic and suction parameters, the normal velocity component of fluid increases over the sheet whereas the tangential velocity component of fluid decreases. Moreover, when the suction parameter, the Prandtl and Eckert numbers increase, the rate of the heat transfer increases. However, when the magnetic parameter increases, the rate of heat transfer reduces. Finally, the solution shows that the results of the analytical method using a special technique have an excellent agreement with numerical solutions.Wed, 18 Sep 2019 19:30:00 +0100Dufour and Soret effects on unsteady heat and mass transfer for Powell-Eyring fluid flow over ...
http://jacm.scu.ac.ir/article_14762_0.html
In the present analysis, the Dufour and Soret effects on unsteady heat-mass transfer of a viscous incompressible Powell-Eyring fluids flow past an expanding/shrinking permeable sheet are reported. The fluid boundary layer develops over the variable sheet with suction/injection to the non-uniform free stream velocity. Under symmetry group of transformations, the governing equations along with three independent variables are converted into a system of PDEs with two independent variables. Finally, by employing the order-reduction technique the PDEs are transformed into ODEs which are then solved numerically. The results are presented graphically and analyzed. The main advantage of this technique is that without any prior knowledge, one can easily find the scaling transformations, expanding velocity, suction/injection velocity, and free-stream velocity. From computed numerical results many important findings are obtained. Most importantly, thermal and concentration overshoots are found for larger values of Dufour and Soret numbers, respectively. Also, thermal and concentration crossing over found for different values of Soret and Dufour numbers, respectively.Sat, 21 Sep 2019 20:30:00 +01003D Optimization of Gear Train Layout Using Particle Swarm Optimization Algorithm
http://jacm.scu.ac.ir/article_14764_0.html
Optimization of the volume/weight in the gear train is of great importance for industries and researchers. In this paper, using the particle swarm optimization algorithm, a general gear train is optimized. The main idea is to optimize the volume/weight of the gearbox in 3 directions. To this end, the optimization process based on the PSO algorithm occurs along the height, length, and width of the gearbox to achieve the smallest possible gearbox. The constraints are divided into three types named geometrical, design and control constraints. The optimization process is presented for two and three-stage gear trains and by choosing different values for the gear ratio, input power and hardness of gears. The practical graphs for the optimum value of the weight/volume and all necessary design parameters of gearbox such as the number of stages, position, modulus of gears, face width of gears, and diameter of shafts are also presented. The results are validated by comparing with the results reported in the previous publications.Sun, 22 Sep 2019 20:30:00 +0100Effects of non-uniform suction, heat generation/absorption and chemical reaction with ...
http://jacm.scu.ac.ir/article_14765_0.html
The present investigation focuses on the magnetohydrodynamic Falkner-Skan flow of tangent hyperbolic nanofluids over a stretching/shrinking wedge with variable suction, internal heat generation/absorption and chemical reaction with activation energy. Nanofluid model is composed of ``Brownian motion’’ and ``thermophoresis’’. Transformed non-dimensional coupled non-linear equations are solved by adopting fourth-order R-K method along with the shooting technique. A comprehensive analysis of nanofluid velocity, the relative temperature and its concentration profiles has been addressed. The major outcomes of the current study include that augmentation in Weissenberg parameter, Hartmann number along with suction impede fluid flow and the shrinkage of the related boundary layer while internal heating develops an ascending thermal boundary layer for static and moving (stretching/shrinking) wedge. An increment in reaction rate undermines the nanoparticle concentration while that of activation energy exhibits a reverse trend.Mon, 23 Sep 2019 20:30:00 +0100On Approximate Stationary Radial Solutions for a Class of Boundary Value Problems Arising in ...
http://jacm.scu.ac.ir/article_14788_0.html
In this paper, we consider a non-self-adjoint, singular, nonlinear fourth order boundary value problem which arises in the theory of epitaxial growth. It is possible to reduce the fourth order equation to a singular boundary value problem of second order given by w''-1/r w'=w^2/(2r^2 )+1/2 λ r^2. The problem depends on the parameter λ and admits multiple solutions. Therefore, it is difficult to pick multiple solutions together by any discrete method like finite difference method, finite element method etc. Here, we propose a new technique based on homotopy perturbation method and variational iteration method. We compare numerically the approximate solutions computed by Adomian decomposition method. We study the convergence analysis of both iterative schemes in C^2 ([0,1]). For small values of λ, solutions exist whereas for large values of λ solutions do not exist.Fri, 27 Sep 2019 20:30:00 +0100Optimum design of Liquified Natural Gas Bi-lobe tanks using Finite Element, Genetic Algorithm ...
http://jacm.scu.ac.ir/article_14801_0.html
A comprehensive set of 10 artificial neural networks was developed to suggest optimal dimensions of type ‘C’ Bi-lobe tanks used in shipping of liquefied natural gas. Multi-objective optimization technique considering maximum capacity and minimum cost of vessels were implemented for determining optimum vessel dimensions. Generated populations from genetic algorithm were used by Finite Element Analysis to develop new models and find primary membrane and local stresses to compare with their permissible ranges using PYTHON coding. The optimum design space was mathematically modeled by training 10 artificial neural networks with design variables generated by Taguchi method. The results were compared with actual design data and the 93% achieved accuracy shows the precision of the developed design system.Sun, 06 Oct 2019 20:30:00 +0100Torsional Aeroelasticity of a Flexible VAWT Blade using a Combined Aerodynamic Method by ...
http://jacm.scu.ac.ir/article_14789_0.html
The present research investigates the torsional aeroelasticity of the blade of an H-type vertical axis wind turbine subject to stall and post-stall conditions in various Reynolds regimes, which is experienced by the blade in a full revolution. In order to simulate the aerodynamics, a new model based on a combination of the Double Multi Streamtubes (DMST) model and the nonlinear multi-criteria Cl-a equations, which is depended on the local Reynolds number of the flow, has been proposed. The results indicate that using of multi-criteria function dependent on the Reynolds number for the Cl-a curve has improved the prediction of the torsional behavior of the blade in azimuthal rotation of the blade compared to using single-criterion functions and linear aerodynamics. The blade’s aeroelastic torsion has been studied for various TSR values.Sat, 28 Sep 2019 20:30:00 +0100Influence of Temperature Pulse on a Nickel Microbeams under Couple Stress Theory
http://jacm.scu.ac.ir/article_14800_0.html
In this paper, the vibration of microbeams due to a temperature pulse has been investigated. The thermoelastic coupled equations for microbeam resonator have been derived via the modified theory of couple stress in connection with the generalized thermoelasticity with relaxation time. The analytical expressions for studied fields due to modified couple stress for the microbeam have been obtained by applying the Laplace transform method. In addition, some comparisons have been displayed in graphs to estimate the effects of different parameters such as the couple stress parameter and pulse of temperature on the considered fields. Numerical conclusions demonstrate that the estimation of deflection expected by the new theory is lower than that of the classical one. Comparisons are made with the results of different models in the absence and presence of couple stress theory. Particular cases of interest are also derived.Wed, 02 Oct 2019 20:30:00 +0100Numerical Solution of Caputo-Fabrizio Time Fractional Distributed Order Reaction-diffusion ...
http://jacm.scu.ac.ir/article_14803_0.html
In this paper, we derive a novel numerical method to find out the numerical solution of fractional partial differential equations (PDEs) involving Caputo-Fabrizio (C-F) fractional derivatives. We first find out the approximation formula of C-F derivative of function tk. We approximate the C-F derivative in time with the help of the Legendre spectral method and approximation formula of tk. The unknown function and their derivatives in spatial direction are approximated with the quasi wavelet-based numerical method. We apply this newly derived method to solve the nonlinear distributed order reaction-diffusion in which time-fractional derivative is of C-F type. The accuracy and validity of the proposed method is exhibited by giving a solution to some numerical examples. The obtained numerical results are compared with the analytical results and conclude that our proposed numerical method achieves accurate results. On the other hand, the method is easy to apply on higher-order fractional partial differential equations and variable-order fractional partial differential equations.Tue, 08 Oct 2019 20:30:00 +0100Casson Nanofluid Past a Stretching Sheet with the Effects of Viscous Dissipation, Chemical ...
http://jacm.scu.ac.ir/article_14804_0.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.Tue, 08 Oct 2019 20:30:00 +0100Effect of Chemical Reaction on Bioconvective Flow in Oxytactic Microorganisms Suspended Porous ...
http://jacm.scu.ac.ir/article_14811_0.html
In this paper, the bioconvective flow in a porous square cavity containing oxytactic microorganism in the presence of chemical reaction, is investigated. The bioconvection flow and heat transfer in porous media is formulated based on Darcy model of Boussinesq approximation. The governing partial differential equations are solved using Galerkin finite element method. The computational numerical results are exhibited by the streamlines, isotherms, isoconcentrations of oxygen, isoconcentrations of microorganisms, average Nusselt number, average Sherwood numbers of oxygen concentration and microorganisms. The effects of key parameters such as bioconvection Rayleigh number (Rb), chemical reaction parameter (Kr) and thermal Rayleigh number (Ra) are presented and analyzed. The main finding of this paper is that chemical reaction reduces the strength of isoconcentrations of both oxygen and microorganisms. Chemical reaction shows greater effect on the swimming of the microorganisms, average Nusselt number and average density number.Thu, 10 Oct 2019 20:30:00 +0100Variational Principle for the Generalized KdV-Burgers Equation with Fractal Derivatives for ...
http://jacm.scu.ac.ir/article_14813_0.html
The unsmooth boundary will greatly affect motion morphology of a shallow water wave, and a fractal space is introduced to establish a generalized KdV-Burgers equation with fractal derivatives. The semi-inverse method is used to establish a fractal variational formulation of the problem, which provides conservation laws in an energy form in the fractal space and possible solution structures of the equation.Fri, 11 Oct 2019 20:30:00 +0100