Comparative numerical study of graphene–copper Boger hybrid nanofluid flow with and without aggregation under Robin-type thermal constraints

This study elegantly explores the intricate dynamics of Boger's hybrid nanofluid, a sophisticated blend of ethylene glycol–water infused with graphene and copper nanoparticles, flowing which flows over an inclined, exponentially stretching surface. Employing the Darcy–Brinkman model, it meticulously accounts for porous media resistance, while a Robin-type boundary condition captures nuanced surface heat exchange. The investigation delves into the interplay of magnetic fields, quadratic radiative heat transfer and Joule heating, crafting a rich thermal landscape. Using reliable correlations like Maxwell and Krieger-Dougherty, thermophysical properties are precisely modelled. When solved numerically via MATLAB’s bvp4c, the results reveal that nanoparticle aggregation enhances the thermal profiles but increases the fluid velocity due to the elevated viscosity. Parameters such as viscoelasticity, buoyancy, and magnetic strength intricately shape velocity and temperature distributions, with aggregation amplifying these effects. This study’s insights into skin friction and Nusselt number trends offer a compelling foundation for optimizing heat transfer in electronic cooling and industrial porous systems.