Comparison of LES studies in backward-facing step using Chebyshev multidomain and Legendre spectral element methods

Abstract

Large-eddy simulation (LES) has been increasingly applied to complex shear flows encountered in practical engineering devices. Here, we present the comparison of LES studies performed using the explicit Chebyshev multi-domain method and the semi-implicit Legendre spectral element method. Two different backward-facing step configurations are simulated at Reynolds numbers 5000 and 28; 000. A grid resolution study at Re = 28; 000 is carried out to compare the number of spectral elements required by the two spectral methods to resolve the flow field. Effect of synthetic turbulence at inflow is investigated using two techniques of generating inflow turbulence at Re = 28; 000. In the LES study at Re = 5000, it is observed that a semi-implicit method requires small time step size to correctly predict transition to turbulence.