Unsteady Magnetohydrodynamic Mixed Convection Flow of Micropolar Fluid Past a Permeable Sphere

Abstract

In this paper, the flow and heat transfer characteristics for unsteady mixed convection flow of an electrically conducting micropolar fluid past a permeable sphere are investigated in detail. The effects of thermal radiation and heat generation or absorption are also considered. The governing equations are transformed into nonlinear ordinary differential equations using new coordinate transformations. Solutions are obtained by employing an implicit finite difference method. Numerical results can predict the boundary-layer characteristics even after the point of boundary-layer separation. The remarkable findings are that the mixed convection parameter and the fluid suction through the porous wall considerably enhance the friction factor, couple stress, and Nusselt number; whereas they are found to decrease with the magnetic field parameter and the fluid injection. Due to an increase of the heat generation parameter and the conduction–radiation parameter, the friction factor and the couple stress increase but the Nusselt number decreases. However, the heat absorption parameter leads to the converse characteristics.