Abstract:
As an effective method for mitigating the "grey area" problem, the synthetic turbulence has been extensively used in the hybrid RANS-LES simulations. Due to the existence of the dominated self-sustained oscillation mechanism of cavity flows, the influences of the synthetic turbulence on the results of hybrid simulations are still not clear. Such influences on the zonal and non-zonal hybrid simulations of the cavity flow of
Ma=0.6 are compared in detail:For the shear layer, the synthetic turbulence increases the three-dimensionality of the vortical structures and the turbulent kinetic energy. For the flow inside the cavity, the size of recirculation zone near the aft-wall become larger when the synthetic turbulence (ST) is added. Moreover, the momentum thickness of the shear layer and the mean pressure are reduced in the same region. The mean pressure with synthetic turbulence show good agreement with the experiment measurement. The employment of the ST would induce an additional mode with higher frequency, but has no effects on the Rossiter's modes. Through comparing the spanwise wavenumber spectra at different locations, it is found that the influences of the synthetic turbulence on the simulation results are produced by altering the three-dimensional flow mechanism. This study suggests that the synthetic turbulent fluctuations in the inflow boundary layer would significantly influence the results of the HRLM of the cavity flow, if the three-dimensionality (such as the spanwise instability) is of great concern.