Effects of Shear Work on the Non-Equilibrium Heat Transfer Characteristics of Rarefied Micro/Nano Flows

Abstract

In the current work, the impact of shear work due to the slip velocity on non-equilibrium heat transfer in a pressure driven micro/nanochannel is<br><br>evaluated under constant wall heat flux condition. The DSMC method is employed as our numerical tool. Implementation of the wall heat flux in<br><br>the DSMC method is performed using the “modified Iterative technique” which in general eliminates the difficulty of implementation in adiabatic<br><br>conditions and improves the convergence speed. We investigate the effects of rarefaction, property variations and compressibility. The numerical<br><br>results show that shear stress on the walls significantly affects all aspects of the flow behavior and heat transfer through micro/nano channel such<br><br>as the velocity slip and heat flux rates. We also analyze the counter gradient heat flow phenomenon appearing at the cooling conditions. The shear<br><br>work always behaves like a heat source (heat flux) due to a considerable heat generation made by the slip velocity at the wall. The latter could be<br><br>formulated as us× τxy. It is observed that this heat source affects the heat flux applied to the walls and may overcome the wall heat flux, i.e., in the<br><br>case of low cooling heat flux condition, shear work causes the flow field to be heated