Slip effects and heat transfer in unsteady stagnation flow of ternary hybrid nanofluids over a rigid plate in porous media using a two-parameter scaling method

This study aims to enhance efficiency in material extrusion and manufacturing. It examines the unsteady stagnation flow of a ternary hybrid nanofluid, comprising aluminum oxide, zinc oxide, and iron(II,III) oxide nanoparticles dispersed in water. The flow is analyzed over a rigid plate with slip effects and heat generation and absorption in porous media. Using the Two-parameter scaling method, the governing equations are simplified into coupled similarity equations and solved by the bvp4c function in Matlab. Dual solutions are observed for decelerating flow, while only a single solution exists for accelerating flow, with stability analysis confirming the first solution as stable and physically workable. The results show that increasing the Darcy number decreases both skin friction and heat transfer rate, while higher nanoparticle volume fraction improves thermal performance. The Nusselt number increases with higher velocity slip and nanoparticle volume fraction but decreases with the Darcy number, thermal slip, and heat generation/absorption. Ternary hybrid nanofluid more effectively delays boundary layer separation and achieves higher thermal efficiency compared to binary and mono nanofluid. At an unsteadiness parameter of -3.5, they are 0.34% more efficient than binary nanofluid and 0.79% more efficient than mono nanofluid. This study develops a novel similarity transformation and offers valuable insights for thermal change, material extrusion, and manufacturing.