At the moment only the following quantities are sampled: the pressure p, the absolute velocity U (no circumferential component), the relative velocity URel (no circumferential component), the absolute velocity magnitude magU and the relative velocity magnitude magURel.

The inletOutlet boundary condition is normally the same as zeroGradient, but it switches to fixedValue if the velocity vector next to the boundary aims inside the domain (backward flow). The value of that fixedValue is inletValue. See figure ().

Figure: The meaning of inletOutlet boundary condition

U:

boundaryField
{
".*_outlet"
{
type inletOutlet;
value $internalField;
inletValue uniform (0 0 0);
}
}

k, omega, epsilon, T:

boundaryField
{
".*_outlet"
{
type inletOutlet;
value $internalField;
inletValue uniform 0;
}
}

The outlet boundary conditions are displayed in Figure . There are two possible ways how to prescribe the desired behaviour of the simulated fields at the outlet from the computational domain: Prescribing a fixed pressure or adjusting the pressure based on the outlet velocity. The choice of the boundary conditions is done by selection of one item of the drop-down list “Outlet BC”. The rest of the panel is then adjusted to the user’s choice.
The boundary condition “Fixed pressure” has only one editable property, of the same name.
The boundary condition “Outlet vent” adjusts the pressure based on the velocity: , where is the so called resistance. The parameters are

“Resistance”, which specifies the outlet vent resistance ; it can contain multiple resistance if multiple points are to be computed;

“Relaxation”, which specifies the relaxation of the pressure fields between the iterations of the solver;