Computational analysis of Hall current, radiation absorption and diffusion thermo effects on unsteady MHD rotating flow of Casson fluid through porous media with chemical reaction

This study investigates the unsteady free-convective flow of an electrically conducting Casson fluid through a porous medium under the combined influences of Hall current, radiation absorption, Dufour effect, thermal radiation, Joule heating, viscous dissipation, and a homogeneous chemical reaction. The fluid motion is subjected to a uniform transverse magnetic field with variable permeability and oscillatory suction. The governing nonlinear partial differential equations for momentum, energy, and concentration are formulated and transformed into dimensionless form using appropriate similarity transformations. Closed-form analytical solutions are obtained through a perturbation method applied for small fluctuations in permeability. The analysis highlights the roles of key parameters—including the Hall parameter (m), magnetic parameter (M), Dufour number (Du), Prandtl number (Pr), Schmidt number (Sc), thermal and solutal Grashof numbers (Gr, Gm), chemical reaction rate (Kc), radiation parameter (Q1), Joule heating parameter, viscous dissipation parameter, and rotation parameter (R)—on velocity, temperature, and concentration distributions. Engineering quantities such as skin friction, Nusselt number, and Sherwood number are also evaluated. The results show that Hall current enhances secondary flow but increases skin friction, while Dufour effect, radiation absorption, Joule heating, and viscous dissipation significantly elevate fluid temperature. Chemical reaction accelerates mass transfer, and rotation reduces magnetic damping, lowering frictional resistance. These findings provide valuable insights for optimizing heat and mass transfer in MHD energy systems, thermal processing operations, and chemically reactive porous-media environments.