A multiscale discrete velocity method for diatomic molecular gas

Abstract

In the previous study, the multiscale discrete velocity method (MDVM) has been developed for monatomic gas with particle translational motion only. Unlike the unified gas-kinetic scheme (UGKS) and discrete unified gas-kinetic scheme, which are the typical representative of multiscale kinetic methods, MDVM achieves multiscale property by mixing the solution of macroscopic control equations and the Boltzmann equation, without the need to calculate complex interface flux. Therefore, MDVM has a higher computational efficiency. To broaden the application scope of MDVM, the Rykov model, which elucidates the exchange of energy between molecular translational and rotational energies, is introduced into MDVM in this paper. Numerical simulations are conducted for various cases, including one-dimensional shock tube, one-dimensional nitrogen shock structure, two-dimensional lid-driven cavity flow, and two-dimensional hypersonic flows around a flat plate and a blunt circular cylinder. The present results agree well with those from the diatomic UGKS method, demonstrating the developed diatomic MDVM can simulate multi-scale, strongly non-equilibrium, diatomic molecular gas flow while exhibiting certain efficiency improvements compared to the diatomic UGKS.