Assessment of RANS and DES methods for the Ahmed body

Abstract

This paper presents numerical simulations for the prediction of the flow around the Ahmed body, with the 25° and 35° slant angles, obtained with the flow solver ISIS-CFD. A RANS (Reynolds Averaged Navier-Stokes) turbulence model, as EARSM (Explicit Algebraic Stress Model) and two hybrid RANS-LES models, as DES (Detached Eddy Simulation) and IDDES (Improved Delay Detached Eddy Simulation) models, are used. All these turbulence models are based on the k-ω model. The flow for the slant angle 35° is well predicted by all turbulence models with a slight advantage for the IDDES model. However, for the flow with the slant angle 25° only the IDDES hybrid RANS-LES model predict the recirculation bubble on the slant.