Scrutinization of Unsteady Bio-convective Stagnation Slip Flow of Hybrid Nanofluid Past a Riga Wedge in the Presence of Activation Energy and Chemical Reaction

This study examines the rheological effects of a hybrid nanofluid and the swimming behavior of gyrotactic microorganisms in an unsteady flow over an expandable Riga wedge. A stagnation point region, suspended with hybrid nanofluid and microorganisms, is considered, subject to velocity slip at the boundary. The study investigates the bio-convection fluid flow phenomenon and considers the effects of chemical reaction, heat source/sink, mass suction, and activation energy. A precise similarity transformation is used to convert the governing partial differential equations into ordinary differential equations. These are then numerically solved using the shooting technique in MATLAB, specifically with the BVP4C solver. The study scrutinizes the effects of various relevant parameters on the dimensionless profiles of velocity, temperature, concentration, and microorganisms. Furthermore, the surface drag force, heat transfer rate, Sherwood number, and motile microorganism density are calculated. To validate the accuracy of the adopted numerical scheme, a tabular comparison is made between the current results and those from the literature in a limiting case. It is observed that adding Al₂O₃ nanoparticles decreases the fluid velocity, while adding Cu nanoparticles increases it; however, in both cases, the fluid temperature decreases. Increasing the wedge angle parameter enhances the fluid temperature and motile density. The heat transfer coefficient decreases with increasing nanoparticle concentration and wedge angle parameter, whereas the opposite behavior is observed for the Biot number.