The Open Boundary condition describes boundaries in contact with a large volume of fluid. Fluid can both enter and leave the domain on boundaries with this type of condition.
The Boundary condition options for open boundaries are
Normal stress and
No viscous stress.
The Normal stress f0 condition implicitly imposes
.
When Include gravity is selected and
Use reduced pressure not selected in the interface
Physical model section, the
Compensate for hydrostatic pressure approximation (named
Compensate for hydrostatic pressure for compressible flows) check box is available and selected by default. When it is selected, the hydrostatic pressure is automatically added to the pressure entered in
f0 user input.
The No Viscous Stress condition specifies vanishing viscous stress on the boundary. This condition does not provide sufficient information to fully specify the flow at the open boundary and must at least be combined with pressure constraints at adjacent points.
