The pressureNormalInletOutletVelocity is a velocity inlet/outlet boundary condition that applies a zero-gradient condition for outflow (as defined by the flux); and obtains velocity from the flux with a direction normal to the patch faces.


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

Boundary file

    type            patch;

Field file

    // Mandatory entries
    type            pressureNormalInletOutletVelocity;

    // Optional entries
    phi             <word>;
    rho             <word>;

    // Inherited entries;


Property Description Type Required Default
type Type name: pressureNormalInletOutletVelocity word yes -
phi Name of flux field word no phi
rho Name of density field word no rho

The inherited entries are elaborated in:

  • Foam::mixedFvPatchField

  • Sign conventions:

    • positive flux (out of domain): apply zero-gradient condition
    • negative flux (into of domain): derive from the flux with specified direction

Further information


  • N/A

Source code:



  • Introduced in version 1.6