Diffusion Foundations Vol. 26

Abstract: This article investigates the boundary layer flow and heat transfer of an electrically conducting Casson fluid over a stretching wedge by considering the effects of suction/injection, velocity and thermal slips and thermal radiation. By applying the appropriate similarity transformations,the governing partial differential equations are transformed to highly non-linear ordinary differential equations. These resulting similarity equations are then solved by a new analytic method namely DTM-BF, based on differential transformation method (DTM) and base function (BF). A comparativestudy of the present numerical results has been made with the already published results available in the literature. The effects of various governing parameters on the flow and heat transfer characteristics have been discussed graphically.

Abstract: The present literature analyzes the MHD stagnation-point flow of an incompressible fluidover an exponentially stretching/shrinking permeable cylinder in the presence of a transverse magnetic field, and suction/injection. The governing partial differential equations in cylindrical form aretransformed into coupled ordinary differential equations (ODEs) using suitable similarity transformations. These ODEs are solved using optimal homotopy analysis method (OHAM) via Mathematicasoftware BVPh 2.0 package. The effects of various governing parameters such as curvature parameter, magnetic parameter, wall transpiration parameter, velocity ratio parameter and Prandtl number onvelocity and temperature profiles have also been examined graphically.

Abstract: In this paper, we have studied the effects of retardation time of non-Newtonian Oldroyd-B type fluid driven by Helmholtz-Smoluchowski velocity in a micro-channel. The potential electric field is applied along the length of the micro-channel describing by the Poisson–Boltzmann equation. The governing model equation was solved analytically using the classical method of partial differential equations. Analytical solution was simulated with the help of MATHEMATICA software and the graphical results for various physical flow parameters were analyzed. Results shows that for larger values of retardation time of a viscoelastic fluid the higher the viscoelastic effect of the fluid and this makes it to need more time for the stress to respond to deformation. Also, the electrokinetic width of micro-channel play a vital rule on the performance of velocity distribution.

Abstract: 3D computational analyses are achieved to predict seriously the influences of thermal buoyancy strength and Dean number on Dean vortices, flow behavior and the rate heat transfer through 180° curved channel of square cross-sectional form. The work shows many results, so this paper emphasizes only on the results of 60° cross-sectional position of the bend duct. The principal partial equations of continuity, momentum and energy are considering in three dimensions under the following assumptions: flow is incompressible and laminar, and it is solved in steady-state. The aforementioned equations are subjected to suitable boundary conditions under following range as: Dean number of De = 125 to 150, Richardson number of Ri = 0 to 2 at fixed value of Prandtl number Pr = 1. The principal results of this work are illustrated as streamline and isotherm contours to draw to flow patterns and temperature distributions respectively. The axial velocity profile is shown versus above conditions, the local Nusselt number is also presented along the wall of 60° cross-sectional position. The results show that the thermal buoyancy can balance the effect of centrifugal force of fluid particles at the angular position of 60°.

Abstract: The current work examines mixed convection boundary layer flow and heat transfer attributes in hydromagnetic micropolar fluid past a heated inclined sheet which stretches nonlinearly along the direction of flow. The impact of variable thermo-physical characteristics of the fluid together with the influence of magnetic field, thermal radiation and viscous dissipation are also checked on the flow field. The modelled governing equations are translated from partial to ordinary differential equations via relevant similarity transformations and the resulting equations are subsequently solved numerically by means of shooting techniques in company with Runge-Kutta integration algorithms. The reactions of the skin friction coefficient, Nusselt number, dimensionless velocity as well as temperature to variations in the emerging controlling parameters are illustrated through different graphs. In the limiting situations, the results obtained exhibit a strong relationship with the existing related works in literature. The facts emanated from this study also reveal that the thickness of the thermal boundary layer grows widely with a rise in the Eckert number and Biot number parameters whereas increasing the material (micropolar) and thermal conductivity parameters have opposite effects on the rate of heat transfer.

Abstract: This paper deals with numerical simulations of forced convection from a pair of identical cylinders arranged in tandem manner inside a square cavity of single inlet and outlet ports. The gap distance between the cylinders is fixed with half of square length. The main purpose of this study is to see the effect of inlet and outlet port positions on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy have been solved using finite-volume method in laminar, steady and two dimensional directions. The work has been done in the range of these conditions: Re = 1 to 40, at fixed Pr = 7.01. Three positions of inlet and outlet port have been selected. The mean results of flow patterns and distribution temperature are illustrated under the contours of streamline and isotherm respectively. The drag and lift coefficients of each cylinder is computed and discussed. The average Nusselt number of both cylinders is also presented and discussed. It was found that the inlet and outlet ports have significant effects on heat transfer from the confined cylinders.

Abstract: In the Present study Soret effect on Magneto Hydro dynamic (MHD) steadytwo-dimensional free convective Casson fluid flow past a moving vertical plate in the presence of thermal radiation and chemical reaction is analysed. The governing partial differential equations of the flow, momentum, energy and mass are transformed into ordinary differential equations using suitable similarity variables. These Non-linear systems of ordinarydifferential equations are solved using Runge - Kutta method along with shooting technique. The effects of various parameters on the velocity, temperature and concentration are discussed. The Skin-friction, Nusselt number and Sherwood number are discussed in detail.

Abstract: This paper deals with a numerical simulation of laminar forced convection heat transfer from a pair of identical circular cylinders placed at the center of square cavity in the line array, the cavity is ventilated with single inlet and outlet ports, the inlet port is located at the middle of left vertical wall and the outlet port is located at the middle of right vertical wall. The work represents the effects of the distance between cylinders and Reynolds number on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy are solved by using finite-volume method. The obtained results are represented and discussed for following conditions: Reynolds number Re = 1 to 40, Prandtl number Pr = 7.01 and the gap distance S = 0.3L to 0.7L, where L is the cavity length. The main results are potted under the streamline and isotherm contours, the total drag coefficient and average Nusselt number of each cylinder is plotted versus studied parameters. It is found that the increase in the gap space distance between cylinders increases the heat transfer rate.

Abstract: An analysis of aCasson fluid flowing over a porous exponentially stretching surface with radiation has been studied. A non-Newtonian fluid model was developed for the flow and similarity analysis used in the transformation process. The model of partial differential equations was transformed into ordinary differential equations and reduced into a system of first order differential equations which was then solved using the Fourth-order Runge-Kutta algorithm alongside the Newton Raphson shooting method. The results have been presented graphically and in tabular form for various controlling parameters of the problem. It is observed that general control can be achieved by the permeability of the surface and the value of the Casson parameter.