Journal of Applied and Computational MechanicsJournal of Applied and Computational Mechanics
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http://jacm.scu.ac.ir/
Feed provided by Journal of Applied and Computational Mechanics. Click to visit.Micropolar Fluid Flow Induced due to a Stretching Sheet with Heat Source/Sink and Surface Heat ...
http://jacm.scu.ac.ir/article_14132_1754.html
Computational and mathematical models provide an important compliment to experimental studies in the development of solar energy engineering in case of electro-conductive magnetic micropolar polymers. Inspired by further understanding the complex fluid dynamics of these processes, we examine herein the non-linear steady, hydromagnetic micropolar flow with radiation and heat source/sink effects included. The transformed non-dimensional governing partial differential equations are solved with the R-K fourth order with shooting technique subjected to appropriate boundary conditions. The characteristics of the embedded parameters are obtained and presented through graphs. Velocity and microrotation of the fluid decreased with enhancing values of material parameter and suction/injection parameter. Electric field parameter has ability to enhance velocity, but temperature shows opposite behaviour. Microrotation increases for both magnetic field and surface temperature parameters.Mon, 30 Sep 2019 20:30:00 +0100An Analytical and Semi-analytical Study of the Oscillating Flow of Generalized Burgers’ Fluid ...
http://jacm.scu.ac.ir/article_14140_1754.html
Unsteady oscillatory flow of generalized Burgers’ fluid in a circular channel tube in the porous medium is investigated under the influence of time-dependent trapezoidal pressure gradient given by an infinite Fourier series. An exact analytical expression for the solution for the fluid velocity and the shear stress are recovered by using the similarity arguments together with the integral transforms. The solution is verified with a semi-analytical solution obtained by employing the Stehfest's method. Using the software Mathcad, numerical calculations have been carried out, and results are presented in graphical illustrations in order to analyze the effects of various fluid parameters on the fluid motion. As expected, with the increase in the permeability of the porous medium, the drag force decreases, which results in an increase in the velocity profile for all kinds of fluid models (a generalized Burgers’ fluid, a Burgers’ fluid, a Maxwell fluid, and an Oldroyd-B fluid). Moreover, it has been observed that the material constants of the generalized Burgers’ fluid, as well as the Burgers’ fluid, are other important factors that enhance the flow velocity performance of the fluid. The velocity-time variation for the generalized Burgers’ fluid, the Oldroyd-B fluid, and the Newtonian fluid is similar to the trapezoidal waveform, whereas it is different for the Burgers’ and Maxwell fluid.Mon, 30 Sep 2019 20:30:00 +0100Irreversibility Analysis of MHD Buoyancy-Driven Variable Viscosity Liquid Film along an ...
http://jacm.scu.ac.ir/article_14130_1754.html
Analysis of intrinsic irreversibility and heat transfer in a buoyancy-driven changeable viscosity liquid along an incline heated wall with convective cooling taking into consideration the heated isothermal and isoflux wall is investigated. By Newton’s law of cooling, we assumed the free surface exchange heat with environment and fluid viscosity is exponentially dependent on temperature. Appropriate governing model equations for momentum and energy balance with volumetric entropy generation expression are obtained and then transformed using dimensionless variables to form set of nonlinear boundary valued problem. Using shooting method with Runge-Kutta-Fehlberg integration scheme, the model is numerically tackled. Pertinent results for the fluid velocity, temperature, skin friction, Nusselt number, entropy generation rate and Bejan number are obtained and discussed.Mon, 30 Sep 2019 20:30:00 +0100A Paired Quasi-linearization on Magnetohydrodynamic Flow and Heat Transfer of Casson Nanofluid ...
http://jacm.scu.ac.ir/article_14156_1754.html
Present study explores the effect of Hall current, non-linear radiation, irregular heat source/sink on magnetohydrodynamic flow of Casson nanofluid past a nonlinear stretching sheet. Viscous and Joule dissipation are incorporated in the energy equation. An accurate numerical solution of highly nonlinear partial differential equations, describing the flow, heat and mass transfer, by a new Spectral Paired Quasi-linearization method is obtained and effect of various physical parameters such as hall current parameter, radiation parameter, Eckert number, Prandtl number, Lewis number, thermophoresis parameter and Brownian motion parameter on the thermal, hydro-magnetic and concentration boundary layers are observed. The analysis shows that variation of different thermo-magnetic parameter induces substantial impression on the behaviour of temperature and nanoparticle distribution. Thermal boundary layer is greatly affected by conduction radiation parameter.Mon, 30 Sep 2019 20:30:00 +0100Numerical Analysis of the Effect of External Circumferential Elliptical Cracks in Transition ...
http://jacm.scu.ac.ir/article_14293_1754.html
The present work investigates the effect of the elliptical three-dimensional (3D) cracks on a pipe with thickness transition, considering internal pressure. Level sets were defined using the extended finite element method (XFEM), the stress intensity factors (SIFs) of 3D cracks were investigated and compared between straight pipes and pipes with thickness transition. The results show that the XFEM is an effective tool for modeling crack in pipes. A pressurized pipe with thickness transition is more sensitive to the feature compared to the straight pipe. Parameters of the transition zone have an influence on stress intensity factors. Quantification of the SIFs associated with cracks in the transition zone of pipes with thicknesses is performed.Mon, 30 Sep 2019 20:30:00 +0100On Bending Response of Doubly Curved Laminated Composite Shells Using Hybrid Refined Models
http://jacm.scu.ac.ir/article_14263_1754.html
This paper presents a static analysis of laminated composite doubly-curved shells using refined kinematic models with polynomial and non-polynomial functions recently introduced in the literature. To be specific, Maclaurin, trigonometric, exponential and zig-zag functions are employed. The employed refined models are based on the equivalent single layer theories. A simply supported shell is subjected to different mechanical loads, specifically: bi-sinusoidal, uniform, patch, hydrostatic pressure and point load. The governing equations are derived from the Principle of Virtual displacement and solved via Navier-Type closed form solutions. The results are compared with results from Layer-wise solutions and different higher order shear deformation theories available. It is shown that refined models with non-polynomial terms are able to accurately predict the through-the-thickness displacement and stress distributions maintaining less computational effort compared to a Layer-wise models.Mon, 30 Sep 2019 20:30:00 +0100Vibration and Buckling Analysis of Functionally Graded Flexoelectric Smart Beam
http://jacm.scu.ac.ir/article_14245_1754.html
In this paper, the buckling and vibration behaviour of functionally graded flexoelectric nanobeam is examined. The vibration and buckling formulations of functionally graded nanobeam are developed by using a new theory that’s presented exclusively for flexoelecteric nano-materials. So by considering Von-Karman strain and forming enthalpy equation based on displacement, polarization and electric potential, electromechanical coupling equations are developed base on Hamilton’ principle. By considering boundary condition of simply support and clamped-clamped and also Euler-Bernoulli beam model, pre-buckling, buckling and the vibration behavior of functionally graded nanobeam affected by flexoelectric will be investigated.Mon, 30 Sep 2019 20:30:00 +0100Asymptotic Approximations of the Solution for a Traveling String under Boundary Damping
http://jacm.scu.ac.ir/article_14288_1754.html
Transversal vibrations of an axially moving string under boundary damping are investigated. Mathematically, it represents a homogenous linear partial differential equation subject to nonhomogeneous boundary conditions. The string is moving with a relatively (low) constant speed, which is considered to be positive. The string is kept fixed at the first end, while the other end is tied with the spring-dashpot system. The asymptotic approximations for the solution of the equations are obtained by application of two time-scale perturbation technique and the characteristic coordinates method. The vertical displacement of the moving system under boundary damping is computed by using specific initial conditions. It is shown that how the introduced damping at the boundary may affect the vertical displacement of the axially moving system.Mon, 30 Sep 2019 20:30:00 +0100Love Wave Propagation in a Fiber-reinforced Layer with Corrugated Boundaries Overlying ...
http://jacm.scu.ac.ir/article_14167_1754.html
Love-type wave generation in a fiber-reinforced medium placed over an inhomogeneous orthotropic half-space is analysed. The upper and lower boundary surfaces of the fiber reinforced medium are periodically corrugated. Inhomogeneity of half-space is caused by variable density and variable shear modules. Displacement components for layer and half-space are derived by applying separable variable technique. Dispersion relation for Love wave is obtained in closed form. Numerical calculations for the achieved dispersion equation are performed. In the numerical examples, the main attention is focused on the effect of corrugation investigation, reinforced parameters and inhomogeneity on the relations between wave number and phase velocity.Mon, 30 Sep 2019 20:30:00 +0100Analysis of the Coupled Nonlinear Vibration of a Two-Mass System
http://jacm.scu.ac.ir/article_14262_1754.html
This paper presents a fixed-end two-mass system (TMS) with end constraints that permits uncoupled solutions for different masses. The coupled nonlinear models for the present fixed-end TMS were solved using the continuous piecewise linearization method (CPLM) and detailed investigation on the effect of mass-ratio on the TMS response was conducted. The investigations showed that increased mass-ratio leads to decreased oscillation frequency and an asymptotic response was obtained at very large mass-ratios. Theoretical solutions to determine the asymptotic response were derived. Also, it was observed that distinct responses can be obtained for the same mass-ratio depending on the mass combination in the TMS. The present fixed-end TMS and the analyses presented give a broader understanding of fixed-end TMS.Mon, 30 Sep 2019 20:30:00 +0100Heat and Mass Transfer Analysis on MHD Peristaltic Prandtl Fluid Model through a Tapered ...
http://jacm.scu.ac.ir/article_14148_1754.html
This paper deals with a theoretical investigation of heat and mass transfer with thermal radiation analysis on hydromagnetic peristaltic Prandtl fluid model with porous medium through an asymmetric tapered vertical channel under the influence of gravity field. Analytical results are found for the velocity, pressure gradient, pressure rise, frictional force, temperature and concentration. The influence of varied governing parameters is discussed and illustrated diagrammatically through a set of figures. It can be seen that the axial velocity enhances with an increase in gravity parameter. It is observed that the temperature of the fluid reduces within the tapered asymmetric vertical channel by an increase in thermal radiation parameter. Blood flow in concentration profile increases with an increase in thermal radiation parameter. It is worth mentioning that the rate of pumping rises in all the four regions, i.e. retrograde pumping region, peristaltic pumping region, free pumping region and an augmented region with an increase in Prandtl fluid parameter.Mon, 30 Sep 2019 20:30:00 +0100Numerical and Analytical Approach for Film Condensation on Different Forms of Surfaces
http://jacm.scu.ac.ir/article_14164_1754.html
This paper tries to achieve a solution for problems that concern condensation around a flat plate, circular and elliptical tube in by numerical and analytical methods. Also, it calculates entropy production rates. At first, a problem was solved with mesh dynamic and rational assumptions; next it was compared with the numerical solution that the result had acceptable errors. An additional supporting relation is applied based on the characteristic of the condensation phenomenon for condensing elements. As it is shown here, due to higher rates of heat transfer for elliptical tubes, they have more entropy production rates, in comparison to circular ones. Findings showed that the two methods were efficient. Furthermore, analytical methods can be used to optimize the problem and reduce the entropy production rate.Mon, 30 Sep 2019 20:30:00 +0100MHD Flow and Heat Transfer of SiC-TiO2/DO Hybrid Nanofluid due to a Permeable Spinning Disk by ...
http://jacm.scu.ac.ir/article_14184_1754.html
This study intends to semi-analytically investigate the steady 3D boundary layer flow of a SiC-TiO2/DO hybrid nanofluid over a porous spinning disk subject to a constant vertical magnetic field. Here, the novel attitude to single-phase hybrid nanofluid model corresponds to considering nanoparticles and base fluid masses to compute solid equivalent volume fraction, solid equivalent density, and also solid equivalent specific heat at constant pressure. The basic PDEs are transformed into dimensionless ODEs using Von Kármán similarity transformations, which are then solved numerically using bvp4c function. Results indicate that mass suction and magnetic field effects diminish all hydrodynamic and thermal boundary layer thicknesses. Finally, a significant report is presented to investigate quantities of engineering interest due to governing parameters’ effects.Mon, 30 Sep 2019 20:30:00 +0100Finite Integral Transform Based Solution of Second Grade Fluid Flow between Two Parallel Plates
http://jacm.scu.ac.ir/article_14247_1754.html
The importance of the slip flow over the no-slip condition is widely accepted in microscopic scaled domains with the direct impact on microfluidic and nanofluidic systems. The popular Navier Stoke’s (N-S) flow model is largely utilized with the slip flow phenomenon. In the present study, the finite integral transform scheme along with the shift of variables is implemented to solve the equation of motion of second grade fluid having third-order mixed partial derivative term. The velocity over the flow regime is studied with both the slip and no-slip boundary conditions for Newtonian and non-Newtonian characteristics by considering the generalized Couette flow. The impact of the pressure gradient and flow time on the velocity is investigated analytically. The output of the present research reveals that due to the slip flow velocity randomly varies at the vicinity of wall surface and such nature hasn’t been found for the no-slip condition. The validation of the present work was done by comparison with the published work and the numerical values, and it shows well verified.Mon, 30 Sep 2019 20:30:00 +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 our study. Two obstacles of the form ꞌ+ꞌ interlaced within a two-dimensional and rectangular channel are the subject of our study. Fluid is Newtonian, turbulent, non-compressible and has constant properties. The number of Reynolds 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 +0100The Development and Application of the RCW Method for the Solution of the Blasius Problem
http://jacm.scu.ac.ir/article_14159_0.html
In this research, a numerical algorithm is employed to investigate the classical Blasius equation which is the governing equation of boundary layer. The base of this algorithm is on the development of RCW (Rahmanzadeh-Cai-White) method. In fact, in this paper, an attempt is made to solve the Blasius equation by using the sum of Taylor and Fourier series. While, in the most common numerical methods, the answer is considered only as a Taylor series. It should be noted that in these algorithms which use Taylor expansion, the values of the truncation error is considerable. But, adding the Fourier series to the Taylor series leads to reduce the amount of the truncation error. However, the results of this research show the RCW method has the ability to achieve the accuracy of analytical solution. Besides, it is well illustrated that the accuracy of RCW method is higher than the Runge-Kutta one.Mon, 04 Mar 2019 20:30:00 +0100Buckling and free vibration analysis of fiber metal-laminated plates resting on partial elastic ...
http://jacm.scu.ac.ir/article_14158_0.html
This research presents, buckling and free vibration analysis of fiber metal-laminated (FML) plates on a total and partial elastic foundation using the generalized differential quadrature method (GDQM). The partial foundation consists of multi-section Winkler and Pasternak type elastic foundation. Taking into consideration the first-order shear deformation theory (FSDT), FML plate is modeled and its equations of motion and boundary conditions are derived using Hamilton’s principle. The formulations include Heaviside function effects due to the nonhomogeneous foundation. The novelty of this study is considering the effects of partial foundation and in-plane loading, in addition to considering the various boundary conditions of FML plate. A computer program is written using the present formulation for calculating the natural frequencies and buckling loadings of composite plates without contact with elastic foundation and composite plates resting on partial foundations. The validation is done by comparison of continuous element model with available results in the literature. The results show that the constant of total or partial spring, elastic foundation parameter, thickness ratio, frequency mode number and boundary conditions play an important role on the critical buckling load and natural frequency of the FML plate resting on partial foundation under in-plane force.Mon, 04 Mar 2019 20:30:00 +0100A new adaptive extended Kalman filter for a class of nonlinear systems
http://jacm.scu.ac.ir/article_14168_0.html
This paper proposes a new adaptive extended Kalman filter (AEKF) for a class of nonlinear systems perturbed by noise which is not necessarily additive. The proposed filter is adaptive against the uncertainty in the process and measurement noise covariances. This is accomplished by deriving two recursive updating rules for the noise covariances, these rules are easy to implement and reduce the number of noise parameters that need to be tuned in the extended Kalman filter (EKF). Furthermore, the AEKF updates the noise covariances to enhance filter stability. Most importantly, in the worst case, the AEKF converges to the conventional EKF. The AEKF performance is determined based on the mean square error (MSE) performance measure and the stability is proven. The results illustrate that the proposed AEKF has a dramatic improved performance over the conventional EKF, the estimates are more stable with less noise.Thu, 07 Mar 2019 20:30:00 +0100Upgrading the Seismic Capacity of Pile-Supported Wharfs Using Semi-Active Liquid Column Gas Damper
http://jacm.scu.ac.ir/article_14185_0.html
One of the most important structures in the ports is the wharf and the most common of these wharfs is the pile-supported wharf. In addition to the conventional loads that this structure should withstand, in seismic areas, pile-supported wharfs should have the necessary capacity and strength against seismic excitations. There are some ways to increase the seismic capacity of the berth. One of these methods is to control the vibrations of the pile-supported wharf against earthquake loads using a damper. In this research, for the first time, a new semi-active damper called the semi active liquid column gas damper (SALCGD), was used to reduce the response of pile supported wharf under seismic loads. In the first step by applying different records of the earthquake, the most important parameter of this damper - the optimal opening ratio of the horizontal column- was obtained for this particular structure. In the following, the performance of this damper and its comparison with the similar passive damper (tuned liquid column gas damper (TLCGD)) were discussed. This study showed that the use of this semi-active damper (SALCGD) reduces the displacement of the pile-supported wharf by 35% and reduces the acceleration of the structure by 50% on average. This is while the passive damper (TLCGD) is about 20 percent reducing the displacement and about 30 percent reducing the acceleration of the structure. Therefore, it was observed that the semi-activation of the damper (SALCGD) had a significant improvement in its performance in controlling the vibrations of pile-supported wharf.Sun, 10 Mar 2019 20:30:00 +0100Analysis of transient Rivlin-Ericksen fluid and irreversibility of exothermic reactive ...
http://jacm.scu.ac.ir/article_14202_0.html
The study analysed unsteady Rivlin-Ericksen fluid and irreversibility of exponentially temperature dependent variable viscosity of hydromagnetic two-step exothermic chemical reactive flow along the channel axis with walls convective cooling. The non-Newtonian Hele-Shaw flow of Rivlin-Erickson fluid is driven by bimolecular chemical kinetic and unvarying pressure gradient. The reactive fluid is induced by periodic changes in magnetic field and time. The Newtons law of cooling is satisfied by the constant heat coolant convection exchange at the wall surfaces with the neighboring regime. The dimensionless non-Newtonian reactive fluid equations are numerically solved using a convergent and consistence semi-implicit finite difference technique which are confirmed stable. The response of the reactive fluid flow to variational increase in the values of some entrenched fluid parameters in the momentum and energy balance equations are obtained. A satisfying equations for the ratio of irreversibility, entropy generation and Bejan number are solved with the results presented graphically and discussed quantitatively. From the study, it was obtained that the thermal criticality conditions with the right combination of thermo-fluid parameters, the thermal runaway can be prevented. Also, the entropy generation can minimize by at low dissipation rate and viscosity.Thu, 14 Mar 2019 20:30:00 +0100Entropy generation of variable viscosity and thermal radiation on magneto nanofluid flow with ...
http://jacm.scu.ac.ir/article_14243_0.html
The present literature illustrates the variable viscosity of dust nanofluid runs over a permeable stretched sheet with thermal radiation. The problem has been modelled mathematically introducing the mixed convective condition and magnetic effect. Additionally analysis of entropy generation and Bejan number provides the fine points of the flow. The model equations are transformed into non-linear ordinary differential equations which are then transformed into linear form using the spectral quasi-linearization method (SQLM) for direct Taylor series expansions that can be applied to non-linear terms in order to linearize them. The validity of our model is established using relative entropy generation analysis. A convergence schematic was obtained graphically. Consequence of various parameters on flow features have been delivered via graphs. Some important findings reported in this study that entropy generation analysis have significant impact in controlling the rate of heat transfer in the boundary layer region. Convergence of the numerical solutions was monitored using the convergence graph. The initial guess values are automatically satisfied the boundary conditions. The resulting equations are then integrated using the SQLM. The effects of varying certain physical parameters of interest are examined and presented.Thu, 04 Apr 2019 19:30:00 +0100Stress Redistribution Analysis of Piezomagnetic Rotating Thick-Walled Cylinder with ...
http://jacm.scu.ac.ir/article_14246_0.html
In this article, the problem of time-dependent stress redistribution of a piezomagnetic rotating thick-walled cylinder under an axisymmetric hygro-thermo-magneto-electro-mechanical loading is analyzed analytically for the condition of plane strain. Using the constitutive equations, a differential equation is found in which there are creep strains. Primarily, eliminating creep strains, an analytical solution for the primitive electric and magnetic potential in addition to stresses is obtained. Then, creep strains are kept and creep stress rates are found by utilizing Norton’s law and Prandtl-Reuss equations for steady-state hygrothermal boundary condition. Lastly, the history of stresses and radial displacement as well as magnetic and potential fields during the time is obtained using an iterative method. In the numerical examples, the effect of angular velocity, hygrothermal loading and thermal and moisture concentration dependency of elastic constants is investigated comprehensively.Mon, 08 Apr 2019 19:30:00 +0100Sequential Implicit Numerical Scheme for Pollutant and Heat Transport in a Plane-Poiseuille Flow
http://jacm.scu.ac.ir/article_14258_0.html
A sequential implicit numerical scheme is proposed for a system of partial differential equations governing the transport of heat and mass in the channel flow of a variable-viscosity fluid. By adopting the backward difference scheme for time derivatives and the central difference scheme for spatial derivatives, an implicit finite difference scheme is formulated. The variable-coefficient diffusive term in each equation is first expanded by differentiation, and the sequential approach then consists in first solving for the temperature and concentration, before solving for the velocity. To verify the numerical scheme, we compare the results with those of a Matlab solver and found very good agreements. We further conduct a numerical convergence analysis and found that the method is convergent. Again, we probe the numerical results against the model equations by studying the time evolution of the flow fields and found that the data, such as the boundary conditions, are perfectly verified. We then study the effects of the flow parameters on the flow fields. The results show that the Solutal and thermal Grashof numbers, as well as the pressure gradient parameter, increased the flow, while the Prandtl number and the pollutant injection parameter both decrease the flow. The conclusion of the study is, therefore that the sequential scheme is of good numerical accuracy and convergent, while a change in the pollutant concentration leads to a small change in the flow velocity due to the opposing effects of viscosity and momentum source.Fri, 12 Apr 2019 19:30:00 +0100Nonlocal elasticity effect on Linear Vibration of Nano-circular plate using Adomian ...
http://jacm.scu.ac.ir/article_14265_0.html
In this study, the small scale effect on the linear free-field vibration of a nano-circular plate has been investigated using nonlocal elasticity theory. The formulation is based on the classical theory and the linear strain in cylindrical coordinates. To take into account the small scale and the linear geometric effects, the governing differential equation based on the nonlocal elasticity theory was extracted from Hamilton principle while the inertial effect as well as the shear stresses effect was ignored. Effect of nonlocal parameter is investigated by solving the governing equation using Adomian decomposition method (ADM) for the clamped and simply supported boundary conditions. By using this method, first five axisymmetric natural frequencies and displacements of nano-circular plate are obtained one at a time and some numerical results are given to illustrate the influence of nonlocal parameters on the natural frequencies and displacements of nano-circular plate. For the purpose of comparison, the linear equations were solved by the analytical method. Excellent agreements were observed between the two methods. This indicates that the latter method can be applied to seek the linear solution of nano-circular plate with a high accuracy while simplifying the problem.Wed, 17 Apr 2019 19:30:00 +0100VISCOELASTIC MICROPOLAR CONVECTION FLOWS FROM AN INCLINED PLANE WITH NONLINEAR TEMPERATURE: ...
http://jacm.scu.ac.ir/article_14296_0.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. The 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.Sat, 11 May 2019 19:30:00 +0100THREE DIMENTIONAL CASSON - CARREAU NANO FLUID FLOW
http://jacm.scu.ac.ir/article_14411_0.html
The current work inquired the computational analysis of three dimensional Casson and Carreau nanofluid flow concerning the convective conditions. After using appropriate self-similarity functions, the flow equations are modified to nonlinear ODEs system. The solution to the modified system is evaluated by numerical technique. The significant results are to inquire the impacts of involving variables on flow characteristics. We have evaluated the outcomes to the friction factors. The outcomes to local Nusselt are evaluated. The outputs to Sherwood number are evaluated. Favourable comparison was performed with before available outcomes for correlating the present results. The achieved results are matched to solutions which are obtained by other researchers. The solution is presented for flow characteristics in the case of Casson and Carreau fluids. Velocities reduce for 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 thermohoresis 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, rate of heat transfer and increase in the rate of mass transfer in case of Casson and Carreau nanofluids.Mon, 13 May 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 (600Tue, 14 May 2019 19:30:00 +0100Efficient solution of nonlinear Duffing oscillator
http://jacm.scu.ac.ir/article_14428_0.html
In this paper, the efficient multi-step differential transform method (EMsDTM) is applied in order to get 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 the MsDTM and EMsDTM methods are obtained and contrasted with the exact solution or the numerical solution Runge Kutta 4th order (RK4) method. This approach can be easily extended to other nonlinear systems and is therefore widely applicable in engineering and other sciences.Thu, 16 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, the 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, the 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 +0100Exploration of the significance of autocatalytic chemical reaction and Cattaneo-Christov heat ...
http://jacm.scu.ac.ir/article_14430_0.html
During the homogeneous-heterogeneous autocatalytic chemical reaction in the dynamics of micropolar fluid, relaxation of heat transfer is inevitable; hence Cattaneo-Christov heat flux model is investigated in this report. In this study, radiative heat flux through an optically thick medium is treated as nonlinear due to the fact that thermal radiation at low heat energy is distinctly different from that of high heat energy, hence classical approach of using Taylor series for simplification was ignored and implicit differentiation was used leading to temperature parameter. Uniqueness of the present analysis is the consideration of cubic autocatalytic chemical reaction between the homogeneous bulk fluid and two species of catalyst at the wall. Application of similarity analysis enabled us to recast the flow equations in to a set of coupled nonlinear ODEs. The resulting equations along with the appropriate conditions are solved computationally. Graphical illustrations of the effect of pertinent parameters on momentum, heat and mass boundary layers are presented and discussed. The concentration of the homogeneous bulk fluid with microstructures and catalyst at the surface decreases and increases with diffusion ratio respectively. Buoyancy has a decreasing effect on temperature distribution.Thu, 16 May 2019 19:30:00 +0100Analysis of high-order approximations by spectral interpolation applied to one- and ...
http://jacm.scu.ac.ir/article_14444_0.html
The implementation of high-order (spectral) approximations associated with FEM is an approach to overcome the difficulties encountered in the numerical analysis of complex problems. This paper proposes the use of the spectral finite element method, originally developed for computational fluid dynamics problems, to achieve improved solutions to these types of problems. Here, the interpolation nodes are positioned in the zeros of orthogonal polynomials (Legendre, Lobatto, or Chebychev) or equally spaced nodal bases. A comparative study between these bases in the recovery of solutions to 1D and 2D elastostatic problems is performed. Examples are evaluated, and a significant improvement is observed when the SFEM, particularly the Lobatto approach, is used in comparison to the equidistant base interpolation.Sun, 19 May 2019 19:30:00 +0100Beam & Shell Models for Composite Straight or Curved Bridge Decks with Intermediate ...
http://jacm.scu.ac.ir/article_14445_0.html
In this research effort, the generalized warping and distortional problem of straight or horizontally curved composite beams of arbitrary cross section, loading and boundary conditions is presented. An inclined plane of curvature is considered. Additionally, the stiffness of diaphragmatic plates has been introduced in the formulation in order to compare with the case where rigid diaphragms are assumed. Isogeometric tools (NURBS) are employed in order to obtain the results for the 1D formulation and 3D shell models are developed in FEM commercial software for composite cross sections with diaphragms. The number of intermediate diaphragms according to bridges design specifications is compared to the analyzed diaphragmatic arrangements in order to assess the overall structural behavior of bridges decks. For this purpose, examples of curved beam models with open or closed cross sections and various arrangements of diaphragms have been studied.Sun, 19 May 2019 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_0.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.Mon, 20 May 2019 19:30:00 +0100Numerical analysis of transient heat transfer in radial porous moving fin with temperature ...
http://jacm.scu.ac.ir/article_14456_0.html
In this article, a time dependent partial differential equation is used to model the nonlinear boundary value problem describing heat transfer through a radial porous moving fin of a rectangular profile. The study is performed by applying a numerical solver in MATLAB (pdepe), which is a centered finite difference scheme. The thermal conductivity and fin surface emissivity are linearly dependent on temperature while the heat transfer coefficient is given by power law function of temperature. The effects of thermo-physical parameters, such as the Peclet number, surface emissivity coefficient, power index of heat transfer coefficient, convective-conductive parameter, radiative-conductive parameter and non-dimensional ambient temperature on temperature is studied.Thu, 23 May 2019 19:30:00 +0100A parameter uniform numerical scheme for singularly perturbed differential-difference equations ...
http://jacm.scu.ac.ir/article_14461_0.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 a lower order of accuracy. So, to increase the convergence, we propose a hybrid finite difference scheme, in which we use 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.Sun, 26 May 2019 19:30:00 +0100Nonlinear bending analysis of functionally graded plates using SQ4T elements based on twice ...
http://jacm.scu.ac.ir/article_14483_0.html
This paper develops a computational model for nonlinear bending analysis of functionally graded (FG) plates using a four-node quadrilateral element SQ4T within the context of the first order shear deformation theory (FSDT). In particular, the construction of the nonlinear geometric equations are based on Total Lagrangian approach in which motion at the present state compared with the initial state is considered large. Small strain-large displacement theory of von Kármán is used in nonlinear formulations of the quadrilateral element SQ4T with the twice interpolation strategy (TIS). The solution of the nonlinear equilibrium equations is obtained by the iterative method of Newton-Raphson with the appropriate convergence criteria. The present numerical results are compared with the other numerical results available in the literature in order to demonstrate the effectiveness of the developed element. These results also contribute a better knowledge and understanding of nonlinear bending behaviors of these structures.Tue, 04 Jun 2019 19:30:00 +0100Melting Heat Transfer Analysis on Magnetohydrodynamics Buoyancy Convection in an Enclosure: A ...
http://jacm.scu.ac.ir/article_14492_0.html
The roll of melting heat transfer on magnetohydrodynamic natural convection in a square enclosure with heating of bottom wall is examined numerically in this article. The dimensionless governing partial differential equations are transformed into vorticity and stream function formulation and then solved using the finite difference method (FDM). The effects of thermal Rayleigh number (Ra), melting parameter (M) and Hartmann number (Ha) are illustrated graphically. With an increasing melting parameter and Rayleigh number, the rate of fluid flow and temperature gradients are seen to increase. And in the presence of magnetic field, the temperature gradient reduces and hence the conduction mechanism dominated for larger Ha. Greater heat transfer rate is observed in the case of uniform heating compared with non-uniform case. The average Nusselt number reduces with increasing magnetic parameter in the both cases of heating of bottom wall.Tue, 11 Jun 2019 19:30:00 +0100