Abstract

This study analyses magnetohydrodynamic (MHD) flow and heat transfer of two immiscible nanofluids in a vertical porous channel with internal heat generation and absorption. A two-region model is formulated, with one region representing a viscous nanofluid under a magnetic field and the other a porous nanofluid medium. The governing nonlinear equations are solved analytically using the regular perturbation method, and closed-form solutions for velocity, temperature, and concentration are obtained. The results show that increasing the Hartmann number from 0.5 to 1.5 reduces peak velocity by nearly 45% while raising the maximum temperature by about 20%. A rise in porous resistance parameter from 0.2 to 0.8 decreases velocity by over 60% and lowers the temperature by 15%. An increase in thermal conductivity ratio from 0.5 to 1.5 enhances velocity by 35% and temperature by 18%. Heat absorption (ϕ increasing from 0.1 to 1.0) reduces fluid temperature by 25%, while strong chemical reaction (d from 1 to 3) decreases concentration by nearly 30%. The interface between the immiscible fluids generates distinct transport responses in each region, emphasizing the importance of considering multiphase effects. The findings are relevant for porous heat exchangers, liquid-metal thermal devices, nuclear cooling systems, and multiphase energy transport applications.