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Description

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.

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

where:

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

References

  • 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.

Usage

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

Boundary file 

<patchName>
{
    type            wall;
    ...
}

Field file 

<patchName>
{
    // Mandatory entries
    type            nutUBlendedWallFunction;

    // Optional entries
    n               4.0;

    // Inherited entries
    ...
}

where:

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

Tutorial:

Source code:

API:

History:

  • Introduced in version 2.4.0