Transfer Phenomena in Fluid and Heat Flows VI

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Authors: R. Suresh Babu, B. Rushi Kumar, P.A. Dinesh
Abstract: A numerical computation has been carried out, to investigate the effects of Soret and Dufour numbers on mixed convective heat and mass transfer flow for a steady, two dimensional, incompressible, electrically conducting viscous fluid flow over a semi-infinite vertical plate in a saturated porous medium under the influence of magnetic field (Lorentz force) with variable fluid properties. The physical governing equations for the fluid flow represents in the nonlinear PDE's regime, which are reduced into a system of ODE's using similarity transformation. The numerical computation of shooting technique is adopted to analyze the nature of "velocity, temperature, concentration fields, skin friction, heat and mass transfer coefficients" graphically for uniform permeability (UP) as well as variable permeability (VP) and illustrated for various non-dimensional parameters of the physical model. The results of the numerical scheme are validated and a numerical comparison has been done for a particular case with the available literature in the absence of few physical parameters and found that in good agreement.
Authors: Bidemi O. Falodun, C. Onwubuoya, F.H. Awoniran Alamu
Abstract: In this paper, boundary layer flow of non-Newtonian Casson fluids past a semi-infinite porous plate in the presence of thermal radiation, viscous dissipation and heat generation is explored. Fluids of this type act as solid elastic and they are very important in food technology, biological science, etc. The flow took place over a semi-infinite vertical porous plate. The presence of viscous dissipation in the flow equations plays a significant role on flows having high viscosity such as polymers and oils. Thermal radiation and heat generation plays a decisive role in the design of many advanced energy conversion system which operates at higher temperature. Hence, the present study is useful in food processing industries and thermal engineering processes. The flows governing equations are numerically solved with spectral relaxation method (SRM). SRM is an iterative procedure that employs the Gauss-siedel type of relaxation approach to linearize and decoupled the system of coupled differential equations. The influence of controlling parameters on velocity, temperature and concentration profiles are plotted in graphs. Furthermore, numerical computations of the local skin friction, local Nusselt number and local sherwood number are presented in tabular form. Results revealed that the presence of the thermophoresis in the concentration equation has great influence on the velocity and concentration profiles because increasing the thermophoresis parameter intensifies the velocity and concentration profiles.
Authors: Belkacem Ould Said, Mohamed Amine Medebber, Nourddine Retiel
Abstract: The coupled of free convection with surface radiation in an annular region of two concentric vertical cylinders filled with air has been numerically investigated. The steady-state continuity, Navier–Stokes and energy equations were carried out by the finite volume method, and the Discrete Ordinates Method (DOM) was used to solve the radiative heat transfer equation (RTE). The computations have been performed for 103 ≤Ra≤ 106, with the emissivity coefficient of all the walls varying between 0 and 1. The influence of the both, Rayleigh numbers and emissivity coefficient of the wall for fixed height ratio X=0.5 on natural convection and radiation heat transfer in enclosure have been solved. The result shows that surface radiation significantly altered the temperature distribution and the flow patterns, especially at higher Rayleigh numbers. The average Nusselt number has also been discussed for different emissivity through the enclosure.
Authors: H. Thameem Basha, R. Sivaraj, I.L. Animasaun, Oluwole Daniel Makinde
Abstract: This computational study explores the properties of non-uniform heat source/sink on the fluid transport properties of a chemically reacting nanofluid with two types of geometries saturated with porous medium. Simulations have been done to investigate the heat and mass transfer characteristics using Crank-Nicolson scheme. Influence of active parameters such as Hartman number, heat source and sinks, Brownian diffusion, higher order chemical reaction, Prandtl number and thermophoretic diffusivity are graphically presented. Tables demonstrate the significant impact of sundry parameters on skin-friction factor, heat and mass transfer rates. The achieved results expose that the heat source/sink parameter has high influences on the fluid flow and heat transfer characteristics. A decrease in average skin friction factor due to the magnetic field is more significant in the flow on a plate than that of cone.
Authors: Oluwole Daniel Makinde, B.C. Prasanna Kumara, G.K. Ramesh, Bijjanal Jayanna Gireesha
Abstract: In the present analysis, we extended Blasius and Sakiadis problems in Carreau fluids by considering a uniform free stream parallel to a fixed or moving flat plate, which has more practical significance. The effects of radiation and convective boundary condition are also taken into account. The resulting nonlinear momentum and energy equations are simplified using similarity transformations. Numerical solutions have been obtained for the velocity and temperature profiles by employing shooting method coupled with Runge-Kutta-Fehlberg integration scheme. Graphical results for the velocity and temperature fields are sketched and discussed. It is found that temperature of the Blasius problem is always higher than the Sakiadis problem.
Authors: Oluwole Daniel Makinde, Venkateswarlu Malapati, R.L. Monaledi
Abstract: The paper examines the combined effects of Hall current, buoyancy forces, thermal radiation, thermo-diffusion and fluid rotation on an unsteady hydromagmetic boundary layer flow with heat and mass transfer over an impulsively moving vertical plate embedded in a porous medium. Base on some realistic simplified assumptions, the governing equations of momentum, energy and chemical species concentration are obtained and tackled analytically using Laplace transform technique. The numerical values of primary and secondary fluid velocities, fluid temperature and species concentration are displayed graphically while those of skin friction coefficient, Nusselt number and Sherwood number are presented in tabular form for different values of pertinent flow parameters.
Authors: Kanakalata L. Ojha, R.N. Barik, G.C. Dash
Abstract: An analysis is carried on an unsteady two-dimensional squeezing radiative flow of an incompressible, viscous, electrically conducting fluid in the presence of time-varying transverse magnetic field and chemical reaction. The crux of the analysis centres round, time-varying magnetic field, squeezing of the channel, chemical reaction of diffusing species and radiative heat transfer. These phenomena affect momentum, thermal energy and solutal transport mechanism significantly. The modified governing equations with complex boundary conditions contribute to intricacy of the solution. The Runge-Kutta sixth order integration scheme with shooting technique has been applied to solve the ordinary differential equations under similarity transformations. The analysis reveals that the numerical method applied in the present analysis is as effective and consistent as that of Homotopy Analysis Method (HAM). Further, it is interesting to note that the squeezing of the channel width acts adversely to the resistive force due to the presence of a magnetic field and hence suggests a controlling device to nullify the effect.
Authors: Y. Hari Krishna, Gurrampati Venkata Ramana Reddy, Oluwole Daniel Makinde
Abstract: In this analysis, the magnetohydrodynamic flow of a Casson fluid over a permeable stretching sheet in the presence of mass transfer is studied. Using similarity transformations, the governing equations are converted to ordinary differential equations and then solved through MATHEMATICA. The skin friction coefficient and local Sherwood number are analyzed through numerical values for various parameters of interest. The velocity and concentration profiles are illustrated for several pertinent flow parameters. We observed that the Casson parameter and Hartman number have similar effects on the velocity in a qualitative sense. We further analyzed that the concentration profile decreases rapidly in comparison to the fluid velocity when we increased the values of the suction parameter.
Authors: Kharabela Swain, Sampada Kumar Parida, G.C. Dash
Abstract: The effects of non-uniform heat source/sink and viscous dissipation on MHD boundary layer flow of Williamson nanofluid through porous medium under convective boundary conditions are studied. Surface transport phenomena such as skin friction, heat flux and mass flux are discussed besides the three boundary layers. The striking results reported as: increase in Williamson parameter exhibiting nanofluidity and external magnetic field lead to thinning of boundary layer, besides usual method of suction and shearing action at the plate, a suggestive way of controlling the boundary layer growth. It is easy to implement to augment the strength of magnetic field by regulating the voltage in the circuit. Also, addition of nano particle to the base fluid serves as an alternative device to control the growth of boundary layer and producing low friction at the wall. The present analysis is an outcome of Runge-Kutta fourth order method with a self corrective procedure i.e. shooting method.

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