The greyDiffusiveRadiation is a boundary condition that provides a grey-diffuse condition for radiation intensity, I, for use with the finite-volume discrete-ordinates model (fvDOM), in which the radiation temperature is retrieved from the temperature field boundary condition.

An external radiative heat flux can be added using qRadExt. If qRadExtDir is specified, this ray closest to this direction is used. Otherwise, the face normal is used as direction to set qRadExt.


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

Boundary file

    type            patch;

Field file

    // Mandatory entries
    type            greyDiffusiveRadiation;

    // Optional entries
    T               <word>;
    qRadExt         <scalar>;
    qRadExtDir      <vector>;

    // Inherited entries


Property Description Type Required Default
type Type name: greyDiffusiveRadiation word yes -
T Name of temperature field word no T
qRadExt Radiative external flux scalar no 0
qRadExtDir Radiative external flux direction vector no Zero

The inherited entries are elaborated in:

  • mixedFvPatchFields.H

Further information


Source code:



  • Introduced in version 1.6