Abstract
In this study, numerical study and optimization for a mixed convection in a porous cavity due to an inner rotating cylinder were performed by using the Galerkin weighted residual finite element method. An optimum circular cylinder size that maximizes average heat transfer along the hot wall was determined, and numerical simulation was performed for various values of Rayleigh number (between 10(4) and 10(6)), angular rotational velocity of a circular cylinder (between -0.001 and 0.01), Darcy number (between 10(-5) and 10(-2)), and porosity of the porous medium (between 0.25 and 0.5). The rotating cylinder with optimum size was found to have profound effects on the fluid flow and heat transfer characteristics, and 107.20% of heat transfer enhancement is obtained at the highest rotational speed when compared to motionless cylinder configuration. Local and average Nusselt number enhances with higher values of Rayleigh number, angular rotational speed of the cylinder (clockwise rotational direction), porosity, and permeability of the porous medium. Average heat transfer rate along the hot wall increases almost linearly with porosity of the porous medium. The average heat transfer rate versus Darcy number shows a saturated-type nonlinear curve near the step, especially for lower values of Richardson number and Hartmann number.