Effects of viscous dissipation and micropolar heat conduction on thermally radiating MHD flow along a vertical plate

Abstract

This study investigates the combined effects of viscous dissipation and micropolar heat conduction on steady magnetohydrodynamic (MHD) flow of a thermally radiating micropolar fluid along a vertical plate. The governing nonlinear partial differential equations describing momentum, microrotation, and energy transport are formulated by incorporating Joule heating, viscous dissipation, and Rosseland thermal radiation. Using appropriate similarity transformations, the system is reduced to a set of coupled ordinary differential equations and solved numerically by the shooting method alongside the Runge-Kutta-Fehlberg scheme. The influences of key dimensionless parameters, including the magnetic parameter, Eckert number, micropolar material parameter, radiation parameter, and Prandtl number, on velocity, microrotation, and temperature distributions are analyzed in detail. The results reveal that viscous dissipation significantly increases fluid temperature and the thickness of the thermal boundary layer, while enhanced micropolar heat conduction improves thermal diffusion and modifies microrotation behavior. The applied magnetic field suppresses fluid motion due to Lorentz forces but increases thermal energy through Joule heating. Furthermore, variations in radiation intensity significantly influence the heat transfer rate. A rise in the fluid material term decreases the skin friction coefficient by 17.5%. This reduction is attributed to the enhanced microstructure effects, which allow rotation of fluid particles and reduce shear stress. These findings provide useful insights for optimizing thermal management in practical systems such as MHD pumps, nuclear reactor cooling systems, metallurgical processing units, and solar thermal energy devices.