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A new nested-LES wall-modelling approach for computation of high Reynolds number wall-bounded flows is presented. The method couples coarse-grained LES in the full-size domain with fine-grained LES in a minimal flow unit. At each time-step, the velocity field in the full-size domain is rescaled to match its mean and rms fluctuating velocities in the near-wall region to that of the minimal flow unit, while the velocity field in the minimal flow unit is rescaled to match its mean and rms fluctuating velocities in the outerregiontothatofthefull-sizedomain.The method has been applied to LES of turbulent channel flow for 1000≤ Reτ ≤ 10,000. Simulations were performed with a fixed number of grid points at all Reτ , making the computational cost independent of the Reynolds number. The results show that the nested-LES approach can predict the friction coefficient with errors of less than 5% compared to Dean’s correlation, and give one-point statistics in good agreement with available DNS and experimental data.
Author(s):
Yifeng Tang
University of Michigan, Ann Arbor
United States
Rayhaneh Akhavan
University of Michigan, Ann Arbor
United States