Turbulence Models

In the case of flows at high Reynolds number, the choice of the turbulence model is crucial in order to correctly reproduce vortexes, boundary layer laminar to turbulent transitions and other turbulent three dimensional behaviors. Several turbulence models are already available :

  • The RANS models. The RANS equations determine mean flow quantities but they require turbulence models to close them. These equations are provided by the different RANS models assuming different hypothesis on the flow. The incompressible solver provides a k −ε  model which is one of the most widely used turbulence models in CFD.
  • The LES models. As the power of computer increases LES models have become a popular technique in order to simulate turbulence. Those models are based on the assumption that large eddies contain most of the kinetic energy of the flow and dependon the geometry while the smaller ones are considered more universal and independent of the flow’s geometry. Therefore LES models will apply a filter on the flow directly solving large eddies while simulating smaller ones.