The influence of effective slip surface on flow and heat transfer characteristics in a channel

Abstract

In present work, a miniature rectangular groove (MRG) is arranged at the bottom of the rectangular channel, and an effective slip surface is constructed. The flow and heat transfer characteristics in the channel with MRG are numerically investigated by Large Eddy Simulation. The results show that the fluid flows over the spanwise vortices inside MRG rather than over the non-slip solid surface. Therefore, effective slip velocity occurs at the interface between the fluid inside and outside the MRG, which reduces the velocity gradient nearby the MRG. Meanwhile, the spanwise vortices inside the MRG are similar to rolling bearings which exert an additional driving force on the external fluid of MRG to propel the fluid moves forward. Furthermore, the influence range of MRG on the flow field is different upstream and downstream of the MRG, respectively. The result indicates the Nusselt number is closely related to the spanwise vortex intensity of the channel bottom. The slightly strengthened spanwise vortices at the leading and trailing edges of the MRG enhance the fluid mixing and the heat transfer performance is improved to some extent. Compared with the channel without MRG, the effective slip surface can improve heat transfer performance and obtain drag reduction.