The location of two globally representative inlet and outlet points is determined in the same way as for Cartesian Velocity Components. For details, see Automatic Values.

In order to avoid the creation of walls at domain inlets and outlets, the globally representative inlet and outlet pressure values are respectively decreased and increased by 10% of the range of values. For example, globally representative inlet and outlet values of 100 kPa and 90 kPa would be updated to 91 kPa and 99 kPa, respectively.

The initial condition for the pressure field should be the average of the highest value of pressure specified on any of the outlet boundaries and the lowest value of pressure specified on any of the inlet boundaries. This reduces the likelihood of spurious inflow at outlets, or outflow at inlets, during the course of the solution.

For a free surface calculation, you should set a hydrostatic pressure distribution in the heavy fluid, and a constant pressure equal to the free surface value in the light fluid. For details, see Modeling Advice for Free Surface Flow.