Heat and Mass Transfer Research Journal (HMTRJ)

Research Article

Effects of thermal and molecular diffusion on transient free convection flow along an infinite vertical porous plate

Nepal C. Roy¹, S. Siddiqa², Md. A. Hossain¹ and Rama Subba Reddy Gorla³

¹Department of Mathematics, University of Dhaka, Dhaka 1000, Bangladesh.

²Department of Mathematics, COMSATS Institute of Information Technology, Attock, Pakistan.

³Department of Mechanical Engineering, Cleveland State University, Cleveland, Ohio 44115 USA.

Submitted: August 5, 2018; Accepted: December 15, 2018

Abstract

We investigated the effects of thermal and molecular diffusion on transient free convection flow of viscous, incompressible fluid along an infinite vertical porous plate. The governing equations have been reduced to convenient form valid for short, long and all time. The solutions for small and large times have been obtained analytically while the solutions for all time have been carried out numerically using the Keller Box method. A good agreement was found between the numerical solutions for all time and the analytical solutions for short and long time. The astonishing results were that in the case of air, the momentum and concentration boundary layers considerably decrease for higher values of the Schmidt number whereas the maximum velocity increases with the increase of the combined buoyancy parameter. On the contrary, in the case of water, the maximum velocity and the shear stress reduce for higher values of the combined buoyancy parameter. The thicknesses of momentum, thermal and concentration boundary layers are found to decrease owing to the increase of the suction parameter.

Keywords

Thermal Diddusion; Molecular Diffusione; Transient Free Convection; Porous media.

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