Thermal and magnetohydrodynamic analysis of micropolar fluid flow through an anisotropic porous channel with radiation and viscous dissipation

This study examines magnetohydrodynamic (MHD) flow and heat transfer of a micropolar fluid through an anisotropic porous channel, with permeabilities along two principal axes, one inclined relative to the horizontal. Flow occurs in the X-direction under a uniform transverse magnetic field. Imposing no-slip and no-spin boundary conditions, exact symmetric solutions for velocity and microrotation are obtained. Thermal effects, including viscous and micropolar dissipation and nonlinear thermal radiation, are incorporated via the energy equation, and dimensionless temperature profiles are analyzed. Asymptotic analysis reveals that for weak magnetic fields (M→0), pressure forcing and porous resistance dominate, producing broad velocity distributions and sustained microrotation near the walls, while thermal effects remain moderate. For strong magnetic fields (M→∞), Lorentz damping confines motion to thin Hartmann-type boundary layers, with the core velocity scaling as Ucore∼−P/M2 and enhanced thermal effects due to viscous dissipation. In the Newtonian limit (K→0), microrotation vanishes, recovering classical MHD flow, whereas at large micropolarity (K→∞), spin–velocity coupling redistributes shear and sustains micro-vortical structures. Thermal radiation and dissipation enhance the temperature field, particularly at higher Eckert and radiation parameters. The permeability ratio affects flow and thermal profiles: lower values broaden distributions, while higher values suppress core flow. These results highlight the coupled effects of magnetic intensity, micropolarity, anisotropic permeability, and thermal phenomena in porous channels.