Unsteady Stagnation Point Flow of Casson Nanofluid With Melting Heat Transfer Past a Plate in Darcy Porous Medium

ABSTRACT The aim of this article is to explore the unsteady Casson‐nanofluid flow and melting heat transfer over a plate in a Darcy porous medium near a stagnation point. Here, aluminum oxide and silver nanoparticles are suspended in sodium alginate (base fluid) to create nanofluid and this has not till been attended by anyone indicating the novelty of this work. By the appropriate transformations, the foremost partial differential equations (PDEs) are converted to ordinary differential equations (ODEs) which are then numerically solved by applying the Runge–Kutta method with shooting technique using MATHEMATICA software. The effects of several parameters on fluid flow and heat transfer are displayed and discussed in detail with proper physical explanations. It is observed that the fluid velocity near the plate enhances with the rise in the unsteady parameter while a decrease in temperature is detected in this case. Velocity gradient at the plate and the temperature gradient at the plate both are found to reduce due to rise in melting parameter. For the growing volume fraction of nanoparticles as well as for the increasing volume fraction of Ag nanoparticles, the heat transfer coefficient decreases. While previous studies mainly addressed steady flows of usual fluids with simple boundary conditions, the combined influences of non‐Newtonian rheology, nanoparticle‐enhanced thermal properties, transient effects due to unsteadiness and porous resistance remain underexplored. This creates opportunity for deeper analysis of heat and mass transfer mechanisms relevant to industrial and biomedical applications and also these findings reveal various intriguing behaviors indicating the requirement for further investigation of this topic under several conditions.