The atmAlphatWallFunction is a boundary condition that provides a wall constraint on the kinematic turbulent thermal conductivity (i.e. alphat) for atmospheric boundary layer modelling. It assumes a logarithmic distribution of the potential temperature within the first cell.


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

Boundary file

    type            patch;

Field file

    // Mandatory entries
    type            atmAlphatWallFunction;
    Pr              <Function1<scalar>>;
    Prt             <PatchFunction1<scalar>>;
    z0              <PatchFunction1<scalar>>;

    // Optional entries
    Cmu             <scalar>;
    kappa           <scalar>;

    // Inherited entries


Property Description Type Required Default
type Type name: atmAlphatWallFunction word yes -
Pr Molecular Prandtl number Function1<scalar> yes -
Prt Turbulent Prandtl number PatchFunction1<scalar> yes -
z0 Surface roughness length [m] PatchFunction1<scalar> yes -
Cmu Empirical model constant scalar no 0.09
kappa von Karman constant scalar no 0.41

The inherited entries are elaborated in:

  • fixedValueFvPatchField.H
  • Function1.H
  • PatchFunction1.H

Further information


Source code:



  • Introduced in version v2006