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Description

The atmNutUWallFunction is a boundary condition that provides a wall constraint on the turbulent viscosity (i.e. nut) based on velocity (i.e. U) for atmospheric boundary layer modelling. It is designed to be used in conjunction with the atmBoundaryLayerInletVelocity boundary condition.

The governing equation of the boundary condition:

\[u = \frac{u^*}{\kappa} ln \left(\frac{z + z_0}{z_0}\right)\]

where:

Property Description
\(u^*\) Friction velocity
\(\kappa\) von Karman constant
\(z_0\) Surface roughness length [m]
\(z\) Ground-normal coordinate

Usage

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

Boundary file 

<patchName>
{
    type            patch;
    ...
}

Field file 

<patchName>
{
    // Mandatory entries
    type            atmNutUWallFunction;
    z0              <PatchFunction1<scalar>>;

    // Optional entries
    boundNut        <bool>;

    // Inherited entries
    ...
}

where:

Property Description Type Required Default
type Type name: atmNutUWallFunction word yes -
z0 Surface roughness length [m] PatchFunction1<scalar> yes -
boundNut Flag to zero-bound nut near wall bool no false

The inherited entries are elaborated in:

  • nutUWallFunctionFvPatchScalarField.H
  • PatchFunction1.H

Further information

Tutorial:

  • N/A

Source code:

API:

History:

  • Introduced in version v2006