Computational Study of a DrivAer Model by Using the Partially-Averaged Navier-Stokes Approach in Combination with the Immersed Boundary Method

This paper presents calculations of external car aerodynamics by using the Partial-Averaged Navier-Stokes (PANS) variable resolution model in conjunction with the Finite Volume (FV) immersed-boundary method. The work presented here is the continuation of the study reported in Basara et al. [1, 2]. In that work, it was shown that the same accuracy of predicted aerodynamic forces could be achieved for both types of computational meshes, the standard body-fitted mesh and the immersed boundary (IB) Cartesian mesh, by using the Reynolds-Averaged Navier-Stokes (RANS) k-ζ-f model as well as by using the Partially-Averaged Navier-Stokes (PANS) method. Based on the accuracy achieved, Basara et al. [2] concluded that further work could focus on evaluating the turbulence modelling on the immersed boundary meshes only. Furthermore, due to all the known shortcomings of the steady-state approach, in this work we only deal with the Partially Averaged Navier-Stokes (PANS), which belongs to the hybrid RANS-LES (scale resolving/high fidelity) methods. Therefore, we analyze instantaneous and time-averaged results obtained on different meshes (150-300 million computational cells) to show how PANS calculations improve with the mesh refinement and consequently with the resolution of more scales of motion. Comparisons of the PANS results with the experimental data for the well-known DrivAer notchback model (Hupertz et al. [3]) demonstrate the predictive capability of PANS.