Comparison of RANS, DES and DDES Results for ONERA M-6 Wing at Transonic Flow Speed Using an In-House Parallel Code

The very first thought that comes to the mind with the application area of the DES and DDES schemes is a massively separated flow with highly unsteady flowfield. However, for various complex three dimensional cases, there is no prior knowledge of the flowfield in the domain and it may have mild separation or no separation at all with a steady domain. This study is carried out to see that what will be the behaviour of the DES and DDES schemes in comparison with the URANS scheme if they are applied to a steady state case. An in-house mpi code DG-DES is used for the present study. Three different flux computational schemes named Roe, AUSM and HLLC schemes within DES formulation are compared to check the response for the flows without massive separation and unsteadiness. The cases are run in both single and double precision mode for DES formulation using Roe flux computational scheme to appreciate the accuracy of the solver. A good comparison of pressure distribution with the experimental data is obtained for all URANS, DES and DDES simulations. The pressure distribution results for DES scheme using single and double precision agree well with the experimental data. The pressure distribution predicted by DES using Roe, AUSM and HLLC schemes agree well with the experimental data. The computed values of Cl and Cd are also in close approximity to the other studies. The drag predicted by all DES and DDES simulations is lower than the URANS scheme. It indicates that the DES and DDES schemes generate lower dissipation due to switching to the LES mode and hence result in lower drag prediction as compared with the URANS solution. There is no anomaly observed in the flow due to the use of DES or DDES for steady flow case.