A numerical study of the Dufour and Soret effects on unsteady natural convection flow past an isothermal vertical cylinder

Abstract

The Dufour and Soret effects on the unsteady laminar free convective flow with mass transfer flow past a semi-infinite isothermal vertical cylinder were studied numerically. The governing partial differential equations were converted into a non-dimensional form and solved numerically by applying a Crank-Nicolson type of implicit finitedifference method with a tri-diagonal matrix manipulation and an iterative procedure. For the hydrogen-air mixture, which is a non-chemical reacting fluid, the profiles of the unsteady dimensionless velocity, temperature and concentration are shown graphically for the different values of thermal and mass Grashof numbers, thermal diffusion parameters (Soret numbers) and diffusion-thermo parameters (Dufour numbers). Finally, the simulated values of the average skin-friction coefficient, the average Nusselt number and the average Sherwood number are presented. The numerical results reveal that for an increasing Soret number or decreasing Dufour number, the time to reach the temporal maximum and the steady-state decreases for the flow variables. As the Soret number increases or the Dufour number decreases, both the skin friction and the Sherwood number increase, whereas the Nusselt number decreases.

Unsteady MHD Mixed Convection Flow of Chemically Reacting Micropolar Fluid between Porous Parallel Plates with Soret and Dufour Effects

“…The system of nonlinear differential equations (18) subject to boundary conditions (19) evident that the temperature of the fluid increases whereas the concentration decreases with the increasing of Sr and Du. This is because of the difference between the temperatures of the fluid and surface as well as the difference between concentrations of the fluid and surface concentrations are increased with Sr and Du.…”

“…The system of (18) is solved numerically subject to boundary conditions (19) using the quasilinearization method given by Bellman and Kalaba [26]. Let ( , = 1, 2, .…”

“…Hayat and Nawaz [18] investigated analytically the effects of the Hall and ion slip on the mixed convection heat and mass transfer of secondgrade fluid with Soret and Dufour effects. Rani and Kim [19] studied numerically the laminar flow of an incompressible viscous fluid past an isothermal vertical cylinder with Soret and Dufour effects. The effects of chemical reaction and Soret and Dufour on the mixed convection heat and mass transfer of viscous fluid over a stretching surface in the presence of thermal radiation were analyzed by Pal and Mondal [20].…”

Effect of chemical reaction, heat source/sink, and thermal diffusion on transient natural convection through a tube

“…The Soret effect, though generally neglected due to its comparatively smaller magnitude than the effect described by Fick's law has been of research interest by many. [8][9][10][11][12] This is due to the prominent role it plays in processes like the separation of isotopes and gas mixtures having very light H He ( , ) 2 , and medium N air ( , ) 2 molecular weight. Seth et al [13][14][15] studied chemical reaction and radiation of a magnetohydrodynamics (MHD) flow on a vertical plate in motion when in rotation with Hall current applied and reported that chemical reaction reduces the momentum and species concentration.…”

“…It has been found that the generation of mass flux by composition gradients with the influence of temperature gradients creates an effect called the Soret effect which is also known as thermal diffusion. The Soret effect, though generally neglected due to its comparatively smaller magnitude than the effect described by Fick's law has been of research interest by many 8–12 . This is due to the prominent role it plays in processes like the separation of isotopes and gas mixtures having very light $$({H}_{2},He)$$, and medium $$({N}_{2},air)$$ molecular weight.…”