The combined effects of anisotropic porous medium and stably stratified fluid on free convective flow through an annulus

This paper documents the semi-analytical results for transient natural convection fluid flow between two concentric vertical cylinders of infinite lengths in the presence of anisotropic porous medium and stratified fluid. The solutions for the time-dependent coupled second order partial differential equations modelling the flow formation are obtained by using trio-methods: Laplace transform techniques, a numerical procedure based on the Riemann Sum Approximation method and D’Alembert method. Line graphs and contour maps for the fluid velocity and temperature profiles are presented for different physical parameters of interest featuring in the solutions. The inclusion of the stratification and anisotropic parameters in the model has been found to aid the regulation of the fluid flow. Furthermore, from the numerical simulation conducted, it is found that for some saturated stratified fluids, the steady and transient state velocities (as well as the temperatures of the fluid) coincide at large time.