Comparison of Hybrid RANS-LES Methods for Massively Separated Flows
The numerical analysis of massively separated flow around a circular cylinder at a high Reynolds number is presented in this paper. The simulations are carried out using the hybrid RANS-LES simulations, namely detached-eddy simulation (DES) and its modified version, delayed detached-eddy simulation (DDES). The computed pressure and skin friction coefficients around the surface of the circular cylinder are compared with the available experimental data and other numerical studies with encouraging results. The power spectral density (PSD) comparison of DES and DDES is carried out in the region with high vortex shedding and the energy spectrum depicts the energy cascade in line with the Kolmogorov -5/3 theory for both DES and DDES results. It is found that these hybrid RANS-LES simulation techniques are able to simulate the flow physics of the massively separated flows reasonably well. For such type of flows, the results of the modified scheme DDES are similar to the DES simulation with no adverse effects on the quality of the predicted flow field. The additional computational cost of DDES in comparison with DES is also addressed.
KeywordsLarge Eddy Simulation Circular Cylinder High Reynolds Number Skin Friction Coefficient Vorticity Magnitude
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