Non-equilibrium heat transfer in acceleration and pressure-driven Poiseuille flows: A comparative study

Abstract

A comparison of non-equilibrium flow and heat transfer characteristics between the acceleration-driven and pressure-driven Poiseuille flow is made with the aid of the direct simulation Monte Carlo method. In particular we study thermal characteristics like temperature and heat flux profiles, heat flow rates and net heat flow directions for both cases. Our study shows several interesting similarities and contrarieties. Non-equilibrium heat flow phenomenon like a bimodal tangential heat flux profile and a heat flow rate maximum at an intermediate Knudsen number is observed for the case of the pressure-driven flow. For both acceleration and pressure-driven cases, a two-way heat flow is observed in the slip and early transition regime, whereas heat flow is unidirectional in the upper transition regime and beyond. For the pressure-driven Poiseuille flow, the net heat flow is in the opposite direction of mass flow for the entire range of Knudsen number. In the case of the acceleration driven flow, however, the heat flow direction reverses and becomes in the direction of mass flow in the upper transition regime and beyond.