The inletOutlet is a boundary condition that provides a generic outflow condition, with specified inflow for the case of return flow.


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

Boundary file

    type            patch;

Field file

    // Mandatory entries
    type            inletOutlet;
    inletValue      <Field>;

    // Optional entries
    phi             <word>;

    // Inherited entries


Property Description Type Required Default
type Type name: inletOutlet word yes -
inletValue Inlet value field scalarField yes -
phi Name of flux field word no phi

The inherited entries are elaborated in:

  • mixedFaPatchField.H

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

Further information


Source code:



  • Introduced in version v1712