Couple Stress Hybrid Nanofluid Flow over a Shrinking Riga Plate with Electromagnetic and Suction Effect

Abstract

This study investigates the steady two-dimensional boundary layer flow of a couple stress hybrid nanofluid past a shrinking Riga plate. The flow is controlled by an externally powered Riga plate capable of producing Lorentz forces, strengthening flow stabilization. Unlike prior works that focused individually on couple stress fluids, hybrid nanofluids, or Riga plates, this work integrates all three within the framework of a shrinking surface. This unique combination offers new insights into boundary layer control, particularly in advanced microfluidic and cooling applications, where precise regulation of both momentum and heat transfer is crucial. The hybrid nanofluid considered in this study consists of aluminium alloys (AA7072) and (AA7075) nanoparticles dispersed in methanol (CH₃OH). The governing system of partial differential equations is converted to ordinary differential equations using similarity transformations, which are then solved numerically using MATLAB's bvp4c solver. The results reveal that the inclusion of hybrid nanoparticles enhances heat transfer and improves thermal retention compared to the base fluid. Increasing suction significantly stabilizes the boundary layer, suppressing velocity profiles and reducing thermal boundary layer thickness. Conversely, higher values of the Riga plate parameter reduce velocity gradients while causing a slight increase in the thermal boundary layer thickness, indicating a trade-off between flow retardation and heat retention.