The competing effects of high zeta potential and finite ionic size on the thermal behaviour of pseudoplastic flows through confined spaces with hydrophobic surfaces

Abstract

We present Galerkin Finite Element computations of the temperature profile and Nusselt Number associated with the mixed electroosmotic and pressure driven flow of a power law non - Newtonian fluid through a micro/nano channel with velocity slip at the wall. The geometry considered is a parallel plate microchannel and the mathematical model used incorporates the effects of high zeta potential, steric effect, viscous dissipation and Joule heating. Based on the temperature profile and Nusselt Number, we determine the qualitative effect of various hydrodynamic and thermal parameters on the heat transfer performance of the flow and in particular, the influence of the zeta potential and the steric factor. We observe that the zeta potential and steric factor have competing effects that are most prominent near the wall of the microchannel. It is also observed that velocity slip at the wall can enhance the overall convective heat transfer in the fluid. The results of this study offer insight into the thermal design of micro/nano-fluidic systems.