The nutkRoughWallFunction is boundary condition that provides a wall-function for the turbulent viscosity (i.e. nut) when using wall functions for rough walls, based on the turbulent kinetic energy (i.e. k). The condition manipulates the wall roughness parameter (i.e. E) to account for roughness effects.

Parameter ranges: - Roughness height (i.e. Ks)= sand-grain roughness (0 for smooth walls) - Roughness constant (i.e. Cs) = 0.5-1.0.


The condition requires entries in both the boundary and field files.

Boundary file

    type            wall;

Field file

    // Mandatory entries
    type            nutkRoughWallFunction;
    Ks              <scalarField>;
    Cs              <scalarField>;

    // Inherited entries


Property Description Type Required Default
type Type name: nutkRoughWallFunction word yes -
Ks Sand-grain roughness height scalarField yes -
Cs Roughness constant scalarField yes -

The inherited entries are elaborated in:

  • nutkWallFunctionFvPatchScalarField.H

Further information


Source code:



  • Introduced in version 2.4.0