The outletInlet is a generic mixed boundary condition that sets the patch value to a user-specified fixedValue for reverse flows, and treats inflow using a zeroGradient condition.


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

Boundary file

    type            patch;

Field file

    // Mandatory entries
    type            outletInlet;
    outletValue     <Field>;

    // Optional entries
    phi             phi;

    // Inherited entries


Property Description Type Required Default
type Type name: outletInlet word yes -
outletValue Outlet field for reverse flow Field yes -
phi Name of the local mass flux word no phi

The inherited entries are elaborated in:

  • Foam::mixedFvPatchField

  • The mode of operation is determined by the sign of the flux across the patch faces.
  • Sign conventions:
    • Positive flux (out of domain): apply the β€œoutletValue” fixed-value
    • Negative flux (into domain): apply zero-gradient condition

Further information


Source code:



  • Introduced in version 1.5