How Do I Decide on a Turbulence Model?

There are four major classes of turbulence models currently in STAR-CCM+. This section presents broad guidelines as to the applicability of each of these. Further guidance on selecting the specific model variants can be found within the sections that provide details about the models.

Spalart-Allmaras models are a good choice for applications in which the boundary layers are largely attached and separation is mild if it occurs at occurs. Typical examples would be flow over a wing, fuselage or other aerospace external-flow applications.

The Spalart-Allmaras models for RANS equations are not suited to flows that are dominated by free-shear layers, flows where complex recirculation occurs (particularly with heat transfer), or natural convection. This statement does not apply to the Spalart-Allmaras detached eddy model.

K-Epsilon models provide a good compromise between robustness, computational cost and accuracy. They are generally well suited to industrial-type applications that contain complex recirculation, with or without heat transfer.

K-Omega models are similar to K-Epsilon models in that two transport equations are solved, but differ in the choice of the second transported turbulence variable. The performance differences are likely to be a result of the subtle differences in the models, rather than a higher degree of complexity in the physics being captured. These models have seen most application in the aerospace industry. Therefore, they are recommended as an alternative to the Spalart-Allmaras models for similar types of applications.

Reynolds stress transport models are the most complex and computationally expensive models offered in STAR-CCM+. They are recommended for situations in which the turbulence is strongly anisotropic, such as the swirling flow in a cyclone separator.