Effect of hydrodynamic and thermal slip on droplet based thermal management systems

Abstract

Fluid flow in a microchannel is primarily laminar due to viscous forces dominating over body or inertia forces. Hence fluid circulation in a droplet greatly enhances heat transfer. As a result, slip at a wall-fluid interface could have a two fold affect on heat transfer in droplet based thermal systems; the first is a direct result of thermal slip at the fluid-wall interface, the second is due to hydrodynamic slip at the interface which leads to reduction of internal circulation and in turn reduction in heat transfer. In this paper molecular dynamic simulations are used to look at the effects of thermal and hydrodynamic slip separately and then to investigate the cumulative effect of them on heat transfer in moving droplets in a microchannel. The affect of hydrodynamic slip in an isothermal channel is studied and it is observed that circulation is inversely dependent on slip length. A simple model is established that captures this effect and it also shows that the effect of slip on circulation only becomes important when the length scale of the problem is comparable to the order of slip length.