MHD Mixed Convection of Hybrid Ferrofluid Flow over an Exponentially Stretching/Shrinking Surface with Heat Source/Sink and Velocity Slip

Abstract

This paper investigates the mixed convection flow related to Fe3O4-CoFe2O4/water hybrid ferrofluids on stagnation point over an exponentially stretching/shrinking surface with the influence of magnetohydrodynamic (MHD), velocity slip, and heat source/sink. The proposed system of differential equations is reduced using the similarity transformation procedure that is numerically solvable using MATLAB. Dual solutions are obtained for various governing parameters, in which the first solution is found to be in a stable state via the stability analysis. The CoFe2O4 nanoparticles volume fraction increases the heat transfer rate and the skin friction coefficient while delaying the separation of the boundary layer at the bifurcation point. Adding CoFe2O4 nanoparticles in hybrid ferrofluids gives a better heat transfer rate than that obtained with ferrofluids. The presence of a magnetic field enhances the fluid flow velocity. The increased strengths of the heat sink and stretching parameters give better results on the heat transfer, while the results are reversed for the heat source and shrinking parameters. The presence of velocity slip does influence the skin friction and the fluid flow.