The nutUBlendedWallFunction is boundary condition that provides a wall function for the turbulent viscosity (i.e. nut) based on velocity (i.e. U) using a binomial-function wall-function blending method between the viscous and inertial sublayer predictions of \c nut for low- and high-Reynolds number applications.

\[u_\tau = (u_{\tau,vis}^n + u_{\tau,log}^n)^{1/n}\]


Property Description
\(u_\tau\) Friction velocity
\(u_{\tau,vis}\) Friction velocity in the viscous sublayer
\(u_{\tau,log}\) Friction velocity in the inertial sublayer


  • See the section that describes ‘automatic wall treatment’:

    Menter, F., Ferreira, J. C., Esch, T., Konno, B. (2003). The SST turbulence model with improved wall treatment for heat transfer predictions in gas turbines. In Proceedings of the International Gas Turbine Congress. November, 2003. Tokyo, Japan. pp. 2-7.


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

Boundary file

    type            wall;

Field file

    // Mandatory entries
    type            nutUBlendedWallFunction;

    // Optional entries
    n               4.0;

    // Inherited entries


Property Description Type Required Default
type Type name: nutUBlendedWallFunction word yes -
n Blending type scalar no 4.0

The inherited entries are elaborated in:

  • nutWallFunctionFvPatchScalarField.H

  • The full ‘automatic wall treatment’ description also requires use of the \link omegaWallFunctionFvPatchScalarField.H with the \c blending option binomial or with the deprecated blended flag set to on.
  • Suffers from non-exact restart since correctNut() (called through turbulence->validate) returns a slightly different value every time it is called. See nutUSpaldingWallFunctionFvPatchScalarField.C.

Further information


Source code:



  • Introduced in version 2.4.0