Hydrodynamic and thermal transport characteristics of swirling flows through microchannels with interfacial slip

Abstract

Fluid flow and heat transfer characteristics of decaying laminar swirling flow of liquids in microchannels have been theoretically investigated, with the consideration of interfacial slip. The effects of slip–swirl interactions on friction factor and Nusselt number have been investigated. The effect of swirl is found to increase the friction factor, while the velocity slip tends to decrease the same, and the combined effect could either result in an increase or a decrease in the friction factor as compared to that in case of flow without slip and without swirl depending upon the situation. It has been recognized that, for a given slip length, there is a threshold inlet swirl number S0 above which the average friction factor over the entrance length (f¯SS) is higher than that in case of flow with no slip and no swirl (f¯), while, below the threshold swirl number S0, f¯SS<f¯. The threshold inlet swirl number S0 is found to be almost independent of the Reynolds number and the critical radius of inlet Rankine vortex profile for the swirl. It has also been revealed that both the inlet swirl and velocity slip effectively increase the Nusselt number.