Prediction of Wall-Pressure Fluctuations in Channel Flow Using a Hybrid RANS-LES Model with a Wall Function

Abstract Pressure fluctuations at a surface beneath a turbulent boundary layer are of interest in a wide range of engineering applications as a basis for quantifying vibration and flow noise. Pressure fluctuations can be predicted using Large-Eddy Simulation (LES), but the computational cost of conventional wall-resolved LES is excessive due to the very small mesh spacings required for the inner boundary layer. To reduce the number of mesh cells, wall-modelling techniques may be introduced. In this study, the Improved Delayed Detached Eddy Simulation (IDDES) model was investigated as a wall modelling technique using channel flow as a test case, and its performance was compared with wall-resolved LES and wall-modelling based on a wall function. Previous investigations of IDDES, have typically assessed the accuracy of the method in terms of velocity statistics only. However, predictions of the wall-pressure fluctuations were also assessed in this study. Mesh refinement was investigated as a means to improve accuracy. However, IDDES was also combined with a wall function, allowing coarser wall-normal mesh spacings. With these modifications, the wall-pressure wavenumber and frequency spectra could be predicted fairly accurately over a wide range, for friction velocity Reynolds numbers from 2000 to 8000.