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.Preface
http://jacm.scu.ac.ir/article_14260_1754.html
The Special Issue contains six peer -reviewed papers. The papers cover various aspects of computational models of material failure which has been the topic of this special issue. The prediction of fracture and failure of engineering systems and materials has been of interest for many years. Methods to predict material failure can be categorized into continuous approaches to fracture and discrete crack approaches. Gradient-enhanced models, non-local models and phase field models are among the most common representatives of the first class of methods while the extended finite element method (XFEM), meshfree methods, peridynamics or efficient remeshing techniques belong to the latter type. The published papers cover several new methodological aspects of computational methods such as the cracking element method presented by Sun et al., the coupled SFEM-SBFEM by Surendran et al. or new fracture criteria in the context of peridynamics suggested by Zhao. Some contributions also focus on application of computational methods to predict material failure in concrete.Tue, 30 Apr 2019 19:30:00 +0100Modelling of Crack Growth Using a New Fracture Criteria Based Peridynamics
http://jacm.scu.ac.ir/article_13213_1754.html
Peridynamics (PD) is a nonlocal continuum theory based on integro-differential equations without spatial derivatives. The elongation fracture criterion is implicitly incorporated in the PD theory, and fracture is a natural outcome of the simulation. On the other hand, a new fracture criterion based on the crack opening displacement combined with peridynamic (PD-COD) is proposed. When the relative deformation of the PD bond between two particles reaches the critical crack tip opening displacement of the fracture mechanics, we assume that the bond force vanishes. The new damage rule of fracture criteria similar to the local damage rule in conventional PD is introduced to simulate the fracture. In this paper, first, a comparative study between XFEM and PD is presented. Then, four examples, i.e., a bilateral crack problem, double parallel crack, monoclinic crack, and the double inclined crack are given to demonstrate the effectiveness of the new criterion.Tue, 30 Apr 2019 19:30:00 +0100Cyclic and Monotonic Behavior of Strengthened and Unstrengthened Square Reinforced Concrete Columns
http://jacm.scu.ac.ir/article_13349_1754.html
The use of composite materials is an effective technique to enhance the capacity of reinforced concrete columns subjected to the seismic loading due to their high tensile strength. In this paper, numerical models are developed in order to predict the experimental behavior of square reinforced concrete columns strengthened by glass fiber reinforced polymer and steel bars and unstrengthened column under cyclic and monotonic loadings, respectively. Two columns are modeled in the present work. The first one corresponds to the column without strengthening subjected to lateral monotonic loading, and the second one corresponds to the column strengthened by glass fiber reinforced polymer and steel bars subjected to lateral cyclic loading. Comparison of the numerical modeling and the experimental laboratory test results are performed and discussed. A good agreement between the numerical and experimental force-displacement responses is obtained. Moreover, improvements in the strength of the reinforced concrete column subjected to the cyclic loading along with the comparison of the behavior of the strengthened column with the unstrengthened reference column are discussed. The results show a good improvement in the load carrying capacity and ductility of the column. The main objectives of this numerical modeling are to contribute the comprehension of the monotonic and cyclic behavior of the square reinforced concrete columns and to compare the numerical results with the experimental ones.Tue, 30 Apr 2019 19:30:00 +0100Modeling of Self-Healing Concrete: A Review
http://jacm.scu.ac.ir/article_13355_1754.html
Self-healing concrete (SHC) has received a tremendous attention due to its advanced ability of automatic crack detection and crack repairing compared to the standard concrete. Two main approaches which considered as to-date self-healing mechanisms are autogenous and autonomous healing. In the past several years, the effort of the research has been focused on experimental works instead of numerical models to simulate the healing process. The purpose of this study is to provide a comprehensive comparison of different self-healing concrete (cement based materials) modeling approaches which are available. In this review, special attention is given to the autonomous healing model and a few of recent works related to the autogenous healing model are also investigated. Moreover, this review covers both analytical and numerical simulation methods of self-healing concrete model.Tue, 30 Apr 2019 19:30:00 +0100Evaluation of Fracture Parameters by Coupling the Edge-Based Smoothed Finite Element Method and ...
http://jacm.scu.ac.ir/article_13372_1754.html
This paper presents a technique to evaluate the fracture parameters by combining the edge based smoothed finite element method (ESFEM) and the scaled boundary finite element method (SBFEM). A semi-analytical solution is sought in the region close to the vicinity of the crack tip using the SBFEM, whilst, the ESFEM is used for the rest of the domain. As both methods satisfy the partition of unity and the compatibility condition, the stiffness matrices obtained from both methods can be assembled as in the conventional finite element method. The stress intensity factors (SIFs) are computed directly from their definition. Numerical examples of linear elastic bodies with cracks are solved without requiring additional post-processing techniques. The SIFs computed using the proposed technique are in a good agreement with the reference solutions. A crack propagation study is also carried out with minimal local remeshing to show the robustness of the proposed technique. The maximum circumferential stress criterion is used to predict the direction of propagation.Tue, 30 Apr 2019 19:30:00 +0100Electro-magneto-hydrodynamics flows of Burgers fluids in cylindrical domains with time ...
http://jacm.scu.ac.ir/article_13836_0.html
This paper investigates the axial unsteady flow of a generalized Burgers’ fluid with fractional constitutive equation in a circular micro-tube, in presence of a time-dependent pressure gradient and an electric field parallel to flow direction and a magnetic field perpendicular on the flow direction. The mathematical model used in this work is based on a time-nonlocal constitutive equation for shear stress with time-fractional Caputo-Fabrizio derivatives; therefore, the histories of the velocity gradient will influence the shear stress and fluid motion. Thermal transport is considered in the hypothesis that the temperature of the cylindrical surface is constant. Analytical solutions for the fractional differential momentum equation and energy equation are obtained by employing the Laplace transform with respect to the time variable t and the finite Hankel transform with respect to the radial coordinate r. It is important to note that the analytical solutions for many particular models such as, ordinary/fractional Burgers fluids, ordinary/fractional Oldryd-B fluids, ordinary/fractional Maxwell fluids and Newtonian fluids, can be obtained from the solutions for the generalized fractional Burgers' fluid by particularizing the material coefficients and fractional parameters. By using the obtained analytical solutions and the Mathcad software, we have carried out numerical calculations in order to analyze the influence of the memory parameters and magnetic parameter on the fluid velocity and temperature. Numerical results are presented in graphical illustrations. It is found that ordinary generalized Burgers’ fluids flow faster than the fractional generalized Burgers’ fluids.Thu, 11 Oct 2018 20:30:00 +0100Cracking Elements Method for Simulating Complex Crack Growth
http://jacm.scu.ac.ir/article_13932_1754.html
The cracking elements method (CEM) is a novel numerical approach for simulating fracture of quasi-brittle materials. This method is built in the framework of conventional finite element method (FEM) based on standard Galerkin approximation, which models the cracks with disconnected cracking segments. The orientation of propagating cracks is determined by local criteria and no explicit or implicit representations of the cracks' topology are needed. CEM does not need remeshing technique, cover algorithm, nodal enrichment or specific crack tracking strategies. The crack opening is condensed in local element, greatly reducing the coding efforts and simplifying the numerical procedure. This paper presents numerical simulations with CEM regarding several benchmark tests, the results of which further indicate the capability of CEM in capturing complex crack growths referring propagations of existed cracks as well as initiations of new cracks.Tue, 30 Apr 2019 19:30:00 +0100Transient MHD convective flow of fractional nanofluid between vertical plates
http://jacm.scu.ac.ir/article_13837_0.html
Effects of the uniform transverse magnetic field on the transient free convective flowsof a nanofluid with generalized thermal transport between two vertical parallel plates have beenanalyzed. The fluid temperature is described by a time-fractional differential equation withCaputo derivatives. Closed form of the temperature field is obtained by using the Laplacetransform and fractional derivatives of the Wright’s functions. A semi-analytical solution for thevelocity field is obtained by using the Laplace transform coupled with the numerical algorithmsfor the inverse Laplace transform elaborated by Stehfest and Tzou. Effects of the derivativefractional order and physical parameters on the nanofluid flow and heat transfer are graphicallyinvestigated.Thu, 11 Oct 2018 20:30:00 +0100A New Stress Based Approach for Nonlinear Finite Element Analysis
http://jacm.scu.ac.ir/article_14244_1754.html
This article demonstrates a new approach for nonlinear finite element analysis. The methodology is very suitable and gives very accurate results in linear as well as in nonlinear range of the material behavior. Proposed methodology can be regarded as stress based finite element analysis as it is required to define the stress distribution within the structural body with structural idealization and modelling assumptions. The methodology eliminates the lengthy and tedious procedure of step by step and then iterative procedure adopted classically for nonlinear analysis problems. One dimensional problem of a simple bar loaded axially is solved to formulate the basic principles. Two dimensional problem of a cantilever beam bending and a torsional problem are solved for further demonstrating and strengthening the method. Results of torsional problem are verified with experimental results. The method is applicable for material nonlinear analysis only.Tue, 30 Apr 2019 19:30:00 +0100Residual power series method for solving time-fractional model of vibration equation of large ...
http://jacm.scu.ac.ir/article_13838_0.html
The primary aim of this manuscript is to present the approximate analytical solutions of the time fractional order Vibration Equation (VE) of large membranes with the use of aniterative technique namely Residual Power Series Method (RPSM). The fractional derivative isdefined in Caputo sense. Example problems have been solved to demonstrate the efficacy of the present method and the results obtained are verified graphically. The convergence analysis of the proposed method has also been included in this article. It is seen that the present method is found to be reliable, very effective and easy to implement for various kinds of fractional differential equations used in science and engineering.Thu, 11 Oct 2018 20:30:00 +0100The solar air channels: Comparative analysis, introduction of arc-shaped fins to improve the ...
http://jacm.scu.ac.ir/article_13839_0.html
The problem under investigation contains a computational simulation of a specific heat exchanger with complex geometry fins. The problem solved is potentially interesting for researchers and engineers working on solar collectors and aerospace industry. It is known that heat transfer enhancement can be achieved by creating longitudinal vortices in the flow. These vortices can be generated by arc-shaped fins, and a computational analysis of such solar air channels is not a simple task. Therefore, we used a present-day commercial CFD code to solve the problem. The mathematical problem including the main equations and their explanation, as well as the numerical procedure was presented. The impact of arc-fins’ spacings on streamlines and temperature distributions was completely investigated, as well as the heat transfer rate, pressure drop and thermal enhancement factor. The Nusselt number (Nu) and friction loss (f) values of the solar air channel at AR = 1.321 (aspect ratio of channel width-to-height) and S = Pi/2 are found to be around 11.963 % and 26.006 %; 21.645 % and 40.789 %; 26.196 % and 50.314 %; and 30.322 % and 58.355 % higher than that with S = 3Pi/4, Pi, 5Pi/4 and 3Pi/2, respectively. Importantly, the arc-fins with Re = 12,000 at S = Pi/2 showed higher thermal enhancement performance than the one at S = 3Pi/4, Pi, 5Pi/4 and 3Pi/2 around 2.530 %, 6.576 %, 6.615 % and 6.762 %, respectively. This study contains the information which seems to be important for practical engineers.Thu, 11 Oct 2018 20:30:00 +0100Modified multi-level residue harmonic balance method for solving nonlinear vibration problem of ...
http://jacm.scu.ac.ir/article_13841_0.html
Nonlinear vibration behavior of beam is an important issue of structural engineering. In this study, a mathematical modeling of a forced nonlinear vibration of Euler-Bernoulli beam rest on nonlinear elastic foundation is presented and the nonlinear vibration behavior of the beam is investigated by using a modified multi-level residue harmonic balance method. The main advantage of the method is that only one nonlinear algebraic equation is generated at each solution level. The computational time of using the new method is much less than that spent on solving the set nonlinear algebraic equations generated in the classical harmonic balance method. Besides the new method can generate higher-level nonlinear solutions neglected by previous multi-level residue harmonic balance methods. The results obtained from the proposed method compared with the results obtained by a classical harmonic balance method to verify the accuracy of the method which shows good agreement between the proposed and classical harmonic balance method. Besides, the effect of various parameters such as excitation magnitude, linear and nonlinear foundation stiffness, shearing stiffness etc. on the nonlinear vibration behaviors are examined.Sat, 13 Oct 2018 20:30:00 +0100Scalings of inverse energy transfer and energy decay in 3-D decaying isotropic turbulence with ...
http://jacm.scu.ac.ir/article_13845_0.html
Energy development of decaying isotropic turbulence in a 3-D periodic cube with non-rotating or rotating frames of reference is studied through direct numerical simulation using GPU accelerated lattice Boltzmann method. The initial turbulence is isotropic, generated in spectral space with prescribed energy spectrum E(κ)~κm in a range between κmin and κmax. The Taylor microscale Reynolds number Reλ and Rossby number Ro are introduced to characterize the inertial, viscous, and rotational attributes of the system. The focus of this study is on the scalings of early inverse energy transfer and late energy decay in the development of turbulent energy under various conditions through combinations of m, κmin, κmax, Reλ and Ro. First, we demonstrate the validity of the simulation by confirming the quantitative dependence of the decay exponent n on the initial energy spectrum exponent m, at Reλ =255 and Ro=∞, varying the values of m, κmin and κmax. Second, at relatively low Reλ, the decay exponent for different initial spectra statistically fall in respective ranges, all of which agree well with the corresponding analytical predictions. Third, we quantitatively investigate the 3-D inverse energy transfer. Our findings include (i) the exponent of inverse energy transfer spectrum E(κ)~κσ depends on the initial spectrum exponent E(κ) ~ κm: if mWed, 24 Oct 2018 20:30:00 +0100Failure Procedure in Adhesive Composite Joints under Different types of Loading
http://jacm.scu.ac.ir/article_13878_0.html
In this paper, we have used numerical simulation to study failure of adhesive joints in composite plates. To determine the failure load, adhesive joints are subjected to different types of loading and gradual failure of the joint is studied using the finite element method. The composite material failure theory is implemented into the FEM software. Also different geometries for the joint edge are considered and effect of these geometries and fillet chamfer angle on the failure load are investigated.Sun, 04 Nov 2018 20:30:00 +0100Impact of magnetic field on convective flow of a micropolar fluid with two parallel heat sources
http://jacm.scu.ac.ir/article_13902_0.html
A numerical study is performed to analyze the buoyancy convection induced by the combinedeffect of temperature and species gradients inside an inclined square cavity. The two side walls of the cavity are maintained at a constant temperature. A uniformly thin heated plate is placed at the center of the cavity. The horizontal top and bottom walls are adiabatic. Numerical solutions of governing equations are obtained using the finite volume method coupled with the upwind and central difference technique. Numerical results of the two-dimensional flow field governed by the Navier-Stokes equations are obtained over a wide range of physical parameters, namely the Rayleigh number, the Hartmann number, the inclined angle of the magnetic parameter and vortex viscosity parameter. It is observed from the results, the heat transfer rate is reduced when increasing Hartmann number, inclination angle and vortex viscosity parameter. The higher heat transfer rate is obtained based on the Newtonian fluid as compared to the micropolar fluid.Wed, 14 Nov 2018 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 +0100Elastic behavior of functionally graded two tangled circles chamber
http://jacm.scu.ac.ir/article_14043_0.html
This paper presents the numerical elastic solution for a real problem, functionally graded chamber of hydraulic gear pumps under internal pressure. Because of the similarity and complexity for the considering geometry, a bipolar cylindrical coordinate system is used for extract the governing equations. The material properties are considered to vary along the two tangled circles with a power-law function. The two coupled governing equations solved by the differential quadrature method. The results are presented for various material index and show that the complexity in considering geometry and material inhomogeneity can change the stress and displacements value through the geometry efficiently. The results and presented method in this paper for extracting and solving the problem can be used for designing similar geometry more accurate. The results of this research are compared with those reported in the previous work.Fri, 04 Jan 2019 20:30:00 +0100Introduction to the slide modeling method for the efficient solution of heat conduction calculations
http://jacm.scu.ac.ir/article_14053_0.html
Determination of the maximum temperature and its location is the matter of the greatest importance in many technological and scientific engineering applications. In terms of numerical calculations of the heat conduction equation by using uniform mesh increments in space, sometime large computational cost is countered. However, adaptive grid refinement method could be computationally efficient both in terms of accuracy and execution time. In this work, the numerical solution of the heat conduction equation based on the slide modeling method (SMM) is introduced. This method is based on a pre-determined mesh density approach which divides each homogeneous region into different slides and then assigns higher mesh point densities to slides of interest regarding their relative importance by performing some mathematical calculations. The importance of each region is determined by some formulated weighting factors which rely on the estimation of temperature profiles in all regions and slides. To investigate the accuracy and efficiency of the proposed method, a number of different case studies have been considered. The results all revealed the strength of the proposed SMM in comparison with the conventional method (based on uniform mesh point distribution).Fri, 11 Jan 2019 20:30:00 +0100The Urban Path Routing Adjustable Optimization by Means of Wavelet Transform and Multistage ...
http://jacm.scu.ac.ir/article_14070_0.html
The present paper introduces the optimization algorithm to improve search rate in urban path routing problems using viral infection and local search in urban environment. This algorithm operates based on two different approaches including wavelet transform and genetic algorithm. The variables proposed by driver such as degree of difficulty and difficulty traffic are of the essence in this technique. Wavelet transform as the first part of proposed algorithm derives edges risk; finally multistage genetic algorithm operates to find the optimal solution which is defined as the shortest path. The proposed algorithm is applied to the case study; its performance is efficiency individually investigated and it is compared with other algorithms.Tue, 15 Jan 2019 20:30:00 +0100Evaluation of turbulence on the dynamics of monopile offshore wind turbine under the wave and ...
http://jacm.scu.ac.ir/article_14071_0.html
In recent years, the use of offshore wind turbines has been considered on the agenda of the countries which have a significant maritime boundary due to more speed and stability of wind at sea. The aim of this study is to investigate the effect of wind turbulence on the aero-hydrodynamic behavior of offshore wind turbines with a monopile platform. Since in the sea, the wind turbine structures are under water and structures interactions, the dynamic analysis has been conducted under combined wind and wave loading. The offshore wind turbines have been investigated under two models of normal and severe wind turbulence, and the results of this study show that the amplitude of fluctuation of dynamic response of structures is increased with increasing the amount of wind turbulence, and this increase is not necessarily observed in the mean values of responses. Therefore, conducting the dynamic analysis is inevitable in order to observe the effect of wind turbulence on the structures response.Wed, 16 Jan 2019 20:30:00 +0100Viscous dissipation impact on free convection flow of Cu-water nanofluid in a circular ...
http://jacm.scu.ac.ir/article_14076_0.html
In this work, free convection of Cu-water nanofluid in an enclosure by considering internally heat generated in the porous circular cavity and the impacts of viscous dissipation are numerically evaluated by control volume finite element method (CVFEM). We maintain the outer and inner sides of the circular porous enclosure at a fixed temperature while insulating the other two walls. We examined the impacts of diverse effective parameters including the Rayleigh number, viscous dissipation, and nanofluid concentration on features of heat transfer and fluid flow. Also, a new correlation for average Nusselt number is developed according to the study’s active parameters. It can be deduced by the results that the maximum value of the temperature is proportional to viscous dissipation parameter.Sun, 20 Jan 2019 20:30:00 +0100Correlation between the weld residual stresses and it’s tensile and impact strength
http://jacm.scu.ac.ir/article_14093_0.html
The tensile strength, impact strength and the hardness of the weld were determined. A criteria was proposed for describing the effect of residual stress on the weld mechanical properties. Dimensionless parameters Rya (the average of residual stress over the material yield strength), Rym (the maximum residual stress over the material yield strength), Ru2 (the difference of residual stress over the material ultimate strength) and Ru3 (the difference ratio between the maximum and minimum of three-dimensional residual stresses over the material ultimate strength) were presented to describe the influence of residual stresses on the actual mechanical behavior of the welded pipe. Maximum Rya criterion and lowest strength were obtained at the weld gap center on the external surface of the pipe. The sharp decline in Ru2 criteria is in consistent with the sever reduction in impact strength perpendicular to the weld gap.Sat, 02 Feb 2019 20:30:00 +0100Estimating the mode shapes of a bridge using short time transmissibility measurement from a ...
http://jacm.scu.ac.ir/article_14113_0.html
This paper reports on the analysis of the signals sent by accelerometers fixed on the axles of a vehicle which passes over a bridge. The length of the bridge is divided into some parts and the transmissibility measurement is applied to the signals recorded by two following instrumented axles. As the transmissibility procedure is performed on the divided signals, the method is called Short Time Transmissibility Measurement. Afterwards, a rescaling process is accomplished in order to estimate the bridge mode shapes. The numerical results indicate that the method can calculate the mode shapes of the bridge accurately. It is demonstrated that short time transmissibility method does not depend on the excitation characteristics contrary to the other related methods which assume that the excitation should be white noise. Generally, the bridge mode shapes may be invisible due to the excitation exerted by the road profile. This issue is also resolved by subtracting the signals from the successive axles. Finally, the signals are contaminated with noise and the robustness of the method is investigated.Thu, 07 Feb 2019 20:30:00 +0100Numerical Modeling and Multi Objective Optimization of Face Milling of AISI 304 Steel
http://jacm.scu.ac.ir/article_14114_0.html
There is a requirement to find accurate parameters to accomplish precise dimensional accuracy, excellent surface integrity and maximum MRR. This work studies the influence of various cutting parameters on output parameters like Cutting force, Surface roughness, Flatness, and Material removal rate while face milling. A detailed finite element model was developed to simulate the face milling process. The material constitutive behavior is described by Johnson-Cook material model and the damage criteria is established by Johnson-Cook damage model. The result indicate significant effects of all three cutting parameters on MRR, both feed rate and depth of cut have significant effect on cutting force. Also, feed rate has significant effect on PEEQ and none of the parameters have effect on flatness.Thu, 07 Feb 2019 20:30:00 +0100Study of MHD second grade flow through a porous microchannel under the Dual-Phase-Lag heat and ...
http://jacm.scu.ac.ir/article_14115_0.html
A semi-analytical investigation has been carried out to analyze unsteady MHD second grade flow under the Dual-Phase-Lag (DPL) heat and mass transfer model in a vertical microchannel filled with porous material. Diffusion thermo (Dufour) effects and homogenous chemical reaction are considered as well. The governing partial differential equations are solved by using Laplace transform method while its inversion is done numerically using INVLAP subroutine of MATLAB. The numerical values of fluid velocity, fluid temperature and species concentration are demonstrated through graphs while the numerical values of skin friction, heat transfer rate and mass transfer rate presented in tabular form for different values of parameters that govern the flow. For the first time, a comparison of heat transfer utilizing the classical Fourier’s heat conduction model, hyperbolic heat conduction Cattaneo-Vernotte (CV) model and the DPL model is carried out for the flow of a second grade fluid. It is found that the differences between them vanish at dimensionless time t=0.4 (for temperature) and at t=0.5 (for velocity) i.e. at a time where the system reaches steady state. The influence of phase lag parameters in both thermal and solutal transport on the fluid flow characteristics have been deciphered and analyzed. The results conveyed through this article would help researchers to understand non-Fourier heat and mass transfer in the flow of second grade fluids which may play a vital role in the design of systems in polymer industries.Thu, 07 Feb 2019 20:30:00 +0100Transient electro-osmotic slip flow of an Oldroyd-B fluid with time-fractional Caputo-Fabrizio ...
http://jacm.scu.ac.ir/article_14128_0.html
In this article, we study the electro-osmotic flow of an Oldroyd-B fluid a with slip condition on the boundary in a circular micro-channel by using a newly definedtime-fractional Caputo-Fabrizio derivative without singular kernel. Closed form solutions for the velocity field is acquired by means of Laplace and finite Hankel transforms.In addition, Stehfest’s algorithm is used for inverse Laplace transform. The solutions for fractional Maxwell, ordinary Maxwell, fractional Newtonian and ordinary Newtonian fluids are obtained as limiting cases of our solution. Finally, the influences of fractional and some important physical parameters on the fluid flow are spotlighted graphically.Tue, 12 Feb 2019 20:30:00 +0100Irreversibility analysis of MHD Buoyancy-Driven Variable Viscosity Liquid Film Along and ...
http://jacm.scu.ac.ir/article_14130_0.html
Analysis of intrinsic irreversibility and heat transfer in a buoyancy-driven changeable viscosity liquid along an incline heated wall with convective cooling putting 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 discussedTue, 12 Feb 2019 20:30:00 +0100INFLUENCE OF HEAT SOURCE/SINK ON MICROPOLAR FLUID FLOW INDUCED DUE TO A PERMEABLE STRETCHING ...
http://jacm.scu.ac.ir/article_14132_0.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.Sat, 16 Feb 2019 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 +0100An analytical and semi-analytical study of the oscillating flow of generalized Burgers’ fluid ...
http://jacm.scu.ac.ir/article_14140_0.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 expressions 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, 25 Feb 2019 20:30:00 +0100Perturbation-iteration algorithm for solving heat and mass transfer in the unsteady squeezing ...
http://jacm.scu.ac.ir/article_14141_0.html
In this paper, heat and mass transfer in the unsteady squeezing flow between parallel plates is analyzed using a perturbation-iteration algorithm. The similarity transformation is used to transform the governing partial differential equations into ordinary differential equations, before being solved. The solutions of the velocity, temperature and concentration are derived and sketched to explain the influence of various physical parameters. The convergence of these solutions is also discussed. The numerical results of skin friction coefficient, Nusselt number and Sherwood number are compared with previous works. The results show that the method which has been used, in this paper, gives convergent solutions with good accuracy.Mon, 25 Feb 2019 20:30:00 +0100Chemical reaction effects on bio-convection nanofluid flow between two parallel plates in a ...
http://jacm.scu.ac.ir/article_14142_0.html
In the present work a mathematical model is developed and analyzed to study the influence of nanoparticle concentration through Brownian motion and thermophoresis diffusion. The governing system of PDEs are transformed into a coupled non-linear ODEs by using suitable variables. The converted equations are then solved by using robust shooting method with the help of MATLAB (bvp4c) software. The impact of dynamic parameters on the flow, energy and concentration are discussed graphically. It is noticed that the mass transfer rate in case of regular fluid is lower to that of nanofluid and axial velocity converges to the boundary very fast in case of temperature dependent viscosity case than to the regular viscous case.Mon, 25 Feb 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_0.html
This paper deals with a theoretical investigation of heat and mass transfer with thermal radiation analysis on hydromagnetic (MHD) 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. An 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 (Rn). Blood flow in concentration profile increases with an increase in thermal radiation parameter (Rn). It is worth mentioning that the rate of pumping raises 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 ( ).Tue, 26 Feb 2019 20:30:00 +0100A paired quasi-linearization on magnetohydrodynamic flow and heat transfer of Casson nanofluid ...
http://jacm.scu.ac.ir/article_14156_0.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. The 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-linearisation 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 the 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.Sat, 02 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 +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 +0100ANALYTICAL AND NUMERICAL APPROACH FOR FILM CONDENSATION ON DIFFERENT FORMS OF SURFACES
http://jacm.scu.ac.ir/article_14164_0.html
This paper seeks to the solution of condensation around of a flat plate, circular and elliptical tube in way of numerical and analytical methods. Also, it calculates the entropy production rates. At first, 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 was applied based on characteristic of condensation phenomenon for condensing elements. As it has been 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 two methods were efficient. Furthermore, analytical methods can be used to optimize the problem and reduce the entropy production rate.Tue, 05 Mar 2019 20:30:00 +0100Love Wave Propagation in a Fiber-reinforced Layer with Corrugated Boundaries Overlying ...
http://jacm.scu.ac.ir/article_14167_0.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 this dispersion equation are performed. In the numerical examples, the main attention is focused on investigation of the effect of corrugation, reinforced parameters and inhomogeneity on the relations between wave number and phase velocity.Wed, 06 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 +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_0.html
This study intends to investigate semi-analytically the steady 3D boundary layer flow of a SiC-TiO2/DO hybrid nanofluid over a porous spinning disk subject to the constant vertical magnetic field. Here, the novel attitude to single-phase hybrid nanofluid model corresponds to considering nanoparticles and base fluid masses to computing 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.Sun, 10 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 +0100Vibration and buckling analysis of functionally graded flexoelectric smart beam
http://jacm.scu.ac.ir/article_14245_0.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.Fri, 05 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 +0100Finite Integral Transform Based Solution of Second Grade Fluid Flow between Two Parallel Plates
http://jacm.scu.ac.ir/article_14247_0.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 present research output 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, 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 +0100ANALYSIS OF THE COUPLED NONLINEAR VIBRATION OF A TWO-MASS SYSTEM
http://jacm.scu.ac.ir/article_14262_0.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 gives a broader understanding of fixed-end TMSSun, 14 Apr 2019 19:30:00 +0100On bending response of doubly curved laminated composite shells using hybrid refined models
http://jacm.scu.ac.ir/article_14263_0.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. In particular Maclaurin, trigonometric, exponential and zig-zag functions are employed. The used 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 in the literature. 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, 15 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 +0100