Influence of Molecular Vibration and Rotation on Wall Heat Flux in Oscillating Rarefied Flow

Abstract

In high temperature environments, molecular vibration and rotation become considerable in flow analysis. We employed unsteady direct simulation Monte Carlo to thoroughly investigate the effects of molecular vibration and rotation on the dynamic response of wall heat flux due to the oscillating flow input in a rarefied environment with high temperature. Three modes of temperature and heat flux (translational, vibrational and rotational) are distinctively quantified to identify the details of the response, in addition to the density and velocity fluctuations. With an increase in the medium temperature, the contribution of internal energy to the heat flux is found to significantly increase; however, the responses vary with the characteristic time of each mode. Besides their usefulness in contributing to the rapid development of space applications, the findings are expected to be significant in designing a thermal protection system for space vehicles in the future.