Optimizing advanced microthermal systems: Synergistic effects of dual streaming potentials and induced magnetic fields in EMHD-driven hybrid flows

This paper presents a comprehensive analytical investigation of electroosmotic magnetohydrodynamic (EOF-MHD) mixed convection flow of Cu/water, SnO 2 /water, and SiO 2 /water nanofluids in a porous vertical microchannel, incorporating viscous dissipation, Joule heating, wall suction/injection, and induced magnetic field. The model is motivated by applications in microelectronic cooling, biomedical transport, electroosmotic micropumps, and lab-on-a-chip systems where electromagnetic control, internal heat generation, and wall mass transfer coexist. The coupled nonlinear governing equations for momentum, energy, electric potential, and magnetic induction are transformed into a dimensionless form and solved analytically using the homotopy perturbation method. The results reveal that wall suction enhances the average Nusselt number by 127.1%, whereas wall injection substantially suppresses heat transfer through thermal boundary-layer thickening. Increasing the Reynolds number improves convective heat transfer by 97.0%, while stronger Joule heating, induced magnetic field, and viscous dissipation reduce the Nusselt number by 58.8%, 46.7%, and 39.6%, respectively. The dual streaming-potential formulation shows that the nonlinear Joule heating term generates two mathematical solution branches, of which only one converges to the physically admissible streaming potential. Among the nanofluids investigated, SiO 2 /water exhibits the highest velocity and volumetric flow rate owing to its lower electromagnetic resistance, whereas Cu/water produces the greatest thermal response and wall shear because of its superior electrical and thermal conductivity. These findings provide new insights into the coupled interactions among electroosmosis, magnetic induction, buoyancy, wall mass transfer, and internal heat generation, and offer practical guidelines for the design and optimization of advanced microfluidic thermal management systems.