THERMAL RADIATION EFFECTS ON MAGNETO-HYDRODYNAMIC HEAT AND MASS TRANSFER FROM A HORIZONTAL CYLINDER IN A VARIABLE POROSITY REGIME

A mathematical model is presented for multiphysical transport of an optically dense, electrically conducting fluid along an isothermal horizontal circular cylinder embedded in a variable-porosity medium. A constant, static, magnetic field is applied transverse to the cylinder surface. The non-Darcy effects are simulated via the second-order Forchheimer drag force term in the momentum boundary layer equation. The cylinder surface is maintained at a constant temperature and concentration. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite-difference scheme. The increasing magnetohydrodynamic body force parameter (M) is found to decelerate the flow. Increasing porosity (c) is found to elevate velocities (i.e., accelerate the flow but decrease temperatures; cool the boundary layer regime). Increasing the Forchheimer inertial drag parameter (A) retards the flow considerably but enhances temperatures. Increasing the Darcy number accelerates the flow due to a corresponding rise in permeability of the regime and concomitant decrease in Darcian impedance. Thermal radiation is seen to reduce both velocity and temperature in the boundary layer. The local Nusselt number is also found to be enhanced with increasing both porosity and radiation parameters.