Thermal non-equilibrium effect of small-scale structures in compressible turbulence

The thermal non-equilibrium effect of the small-scale structures in the canonical two-dimensional turbulence is studied. Comparative studies of Unified Gas Kinetic Scheme (UGKS) and GKS-Navier-Stokes (NS) for Taylor Green flow with initial Ma = 1, Kn = 0.01 and decaying isotropic turbulence with initial Ma(t) = 1, Re-lambda = 20 show that the discrepancy exists both in small and large scales, even beyond the dissipation range to 107/ with accuracy to 8% in the SGS energy transfer of the decaying isotropic turbulence, illustrating the necessity for resolving the kinetic scales even at moderated Re-lambda = 20.