What Is a Wall Treatment?

A wall treatment in STAR-CCM+ is the set of near-wall modeling assumptions for each turbulence model. This term avoids confusion with the term wall functions, which typically refers to only one type of wall treatment.

Three types of wall treatment are provided, although all three might not always be available, depending on the turbulence model:

The high-

wall treatment implies the wall-function-type approach in which it is assumed that the near-wall cell lies within the logarithmic region of the boundary layer.

The low-

wall treatment is suitable only for low-Reynolds number turbulence models in which it is assumed that the viscous sublayer is properly resolved.

The all-

wall treatment is a hybrid treatment that attempts to emulate the high-

wall treatment for coarse meshes and the low-

wall treatment for fine meshes. It is also formulated with the desirable characteristic of producing reasonable answers for meshes of intermediate resolution (that is, when the wall-cell centroid falls within the buffer region of the boundary layer).

The wall treatments have been specialized according to each turbulence model, since assumptions specific to that model need to be made for the wall boundary conditions for the turbulence quantities. Both the high-

and all-

wall treatments share a common need to specify profiles of the mean flow quantities in the near-wall region of turbulent boundary layers, and these profiles are termed wall laws.