Simulation of the unsteady cavitation on the the Delft Twist11 foil using RANS, DES and LES

The unsteady sheet cavitation on the Delft Twist11 foil is simulated using RANS, DES, and LES. Focus of the anal- ysis is for the LES results, but comparisons are made to the results of the other approaches. The LES is run with implicit subgrid modeling while the RANS and DES both are run using the Spalart-Almaras model in order to re- duce the differences between the approaches; in the case of the DES the improved formulation called Delayed DES is used. RANS simulations are performed both with the standard formulation and with the correction proposed by Reboud. The LES gives satisfactory results given the mesh resolution with the major mechanisms governing the shed- ding dynamics captured giving a shedding frequency of 34 Hz compared with the experimentally determined fre- quency of 32.55 Hz. The extent of the cavity is however slightly small and the lift is low. Also the DES agrees rea- sonably well with the experiments while RANS with the correction give a shedding behavior but the mechanisms are not as well represented as in the LES or the DES. The standard formulation of the RANS gives a stationary cavity