New correlations for slip flow and heat transfer over a micro spherical particle in gaseous fluid

Abstract

In this work, a numerical model was established to simulate the gas flow and heat transfer over a micro spherical particle in the slip regime, in which the gas rarefaction effects (slip phenomena and gas compressibility) and temperature-dependent properties were considered. The Navier-Stokes equations and energy equation were adopted to govern the gas flow and heat transfer in the continuum region, for which the velocity slip and temperature jump boundary conditions were implemented at the gas-particle interface to predict the slip phenomena. The influences of the gas compressibility and temperature-dependent properties on the gas flow and heat transfer characteristics were investigated based on the numerical predictions. It shows that the drag force and heat transfer rate on the particle surface decrease due to the gas velocity slip and temperature jump, respectively. The drag force acting on the particle surface increases with the increase of particle temperature, which is caused by the increasing viscosity of the gas around the particle. The heat transfer coefficient decreases as the particle temperature increases, which is caused by the increasing thermal resistance due to the increase of temperature jump. Finally, the novel correlations for drag coefficient and Nusselt number of the rarefied gas flow over a micro spherical particle were proposed, which consider the influences of the gas rarefaction effects and temperature-dependent properties.