Second law analysis of a 3D magnetic buoyancy-driven flow of hybrid nanofluid inside a wavy cubical cavity partially filled with porous layer and non-Newtonian layer

•This paper presents numerical results of the buoyancy-driven flow of a nanofluid in a cavity in the presence of magnetic field.•To encounter the non-Newtonian layer influence, the power-law model is considered.•The solution of the governing equations is obtained by the Galerkin FEM method.•The effects of geometrical parameters are discussed and illustrated.•By simultaneously using non-Newtonian nanofluid and porous media, the heat exchange is positively affected.