Running a Simulation with the Turbulence Suppression Model

Choice of Turbulence Model and Wall Treatment

There is no restriction on the choice of turbulence model when the Transition model is activated. However, it makes the most sense to use models that are designed to resolve the laminar sublayer.

These include (but are not necessarily limited to):

• The Standard Spalart-Allmaras model
• The Realizable Two-Layer K-Epsilon model
• The Lien low-Reynolds number model
• The Standard K-Omega model
• The SST K-Omega model
• The Linear Pressure Strain Two-Layer model

In each case the low- $y^{\text{+}}$ or all- $y^{\text{+}}$ wall treatment model should be used.

Near-Wall Mesh Resolution

Since the wall shear stress is computed using laminar flow relationships rather than wall functions adjacent to a transition boundary, the mesh should be sufficiently fine for acceptable accuracy. A sound approach would be to ensure that the mesh is adequately refined in the turbulent region and that the near-wall mesh spacing is not discontinuous.

Inflow or Free-Stream Turbulence Boundary Conditions

Suppressing turbulence in one region of the flow does not guarantee that the flow will become rapidly turbulent where it is not suppressed. The onset of transition, though not accurately predicted by turbulence models, will be affected by the Reynolds number and the free-stream turbulence values. Some low-Reynolds number turbulence models can be quite sensitive to the free-stream turbulence values, so some artful tuning of the inflow turbulence conditions might be required to get the desired transition effect.