Space-time correlations of near-wall velocity and pressure fluctuations in wall-resolved and wall-modeled large-eddy simulation
摘要
Wall-resolved large-eddy simulation (WRLES) and wall-modeled large-eddy simulation (WMLES) of turbulent channel flow at Reτ ≈ 1000 are performed to explore their capabilities in predicting the space-time correlations of near-wall velocity and pressure fluctuations. Our findings indicate that both WRLES and WMLES can effectively capture the essential features in the wavenumber-frequency spectra. Doppler shifts due to the convection velocity and Doppler broadening caused by the random sweeping effects of large-scale eddies are observed in the wavenumber-frequency spectra. Both methods predict the near-wall velocity fluctuations with reasonable accuracy, but predicting wall pressure fluctuations seems to be more challenging for the current wall modeling approach. Without resolving the viscous sublayer, WMLES slightly overestimates the spectral levels of wall pressure fluctuations in low-wavenumber (or frequency) region. In addition, the two-dimensional spatial spectra indicate that isotropic subgrid-scale models may struggle to accurately capture the anisotropy of small-scale eddies near the wall.