科研之友
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摘要
An energy budget analysis and a posteriori tests of subgrid-scale (SGS) models for large eddy simulation (LES) of stationary highly compressible homogeneous isotropic turbulence are carried out at the turbulent Mach number M-t ranging from 0.4 to 1.0 and the Taylor Reynolds number Re-lambda ranging from 180 to 250. An energy budget analysis shows that the SGS stress T-ij and the SGS heat flux Q j are dominant terms in the current M-t and Re-lambda, ranges, while other terms are significantly smaller than the divergence of the SGS heat flux Q(j) and can be neglected in LES. We perform LES of compressible isotropic turbulence by using several SGS models including a dynamic Smagorinsky model, a dynamic mixed model, and an optimal model. In addition, a modified optimal model is constructed based on the magnitude of the filtered strain-rate tensor vertical bar<(<b>S)over tilde>vertical bar inspired by the physical insight that the region of the large magnitude of the filtered strain-rate tensor plays a significant role in kinetic energy transfer. Spectra, statistics, and scaling of velocity and thermodynamic variables from LES are tested. The modified optimal model performs better than other models, especially for the spectrum of the compressible velocity component at relatively low turbulent Mach numbers and high Taylor Reynolds numbers. The probability density function and the structure functions of velocity and thermodynamic variables are further studied, demonstrating that the statistical properties of the simulated flows are improved by the modified optimal model. Published by AIP Publishing.
