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;
• “Max pressure”, which sets a pressure limit.