Hybrid Simulation of High-Reynolds Number Flows Relying on a Variational Multiscale Model

Abstract

We are interested in the study and improvement of the LES component in hybrid RANS-LES formulations. These models are not designed for blunt-body flows with laminar boundary layers, but it is interesting to examine how they behave in that case. A DDES model is compared with a dynamic Variational multi-scale (DVMS) LES model for two subcritical flows past a cylinder. We then propose a hybridation restricting to DVMS in LES regions. The performances of the different options are compared for subcritical flows and for a flow around a tandem cylinder.

Hybrid Versus Pure-LES Models Comparison for Subcritical Cylinder Flows

“…We reconsider here the two first test cases of [6], with several updates and new computations involving other models. A third test case (see Figure 1), which concerns a high subcritical Reynolds number, is also presented for the assessment of the different turbulence models introduced in this work.…”

“…In the lines of [6], DVMS, DDES and our hybrid model are compared for subcritical flows past cylinders. For low and medium subcritical Reynolds numbers (Re = 3900 and Re = 20000), the computations performed with the turbulent models mentioned above compare well with experimental data and numerical results in the litterature.…”

“…In Computational Fluid Dynamics applications, there is a need for turbulence models which deliver good predictions for flows involving both laminar and turbulent boundary layers, without knowing in advance the regions where turbulence occurs, and then without changing their parameters according to such an a priori knowledge of the flow characteristics. In this work, which extends the study [6], we are interested in the assessment of hybrid models for the computation of subcritical flows with laminar boundary layers and in the improvement of the wake behavior prediction in a hybrid RANS/LES model [5,6,9]. The performances of a DDES model are compared with a dynamic variational multi-scale (DVMS) large eddy simulation model.…”