[lb0331]

Hi, I'm running compressible flow simulations, studying orifice gas throttling. In the actual experiment, there is a 1bar gas chamber at the entrance, and atmospheric pressure directly at the exit. A density-based solver is used, and the operating pressure is set to 0. The fluid domain model and boundary condition values are shown in the figure. Since the inlet flow is not known, the boundary conditions use pressure inlet and pressure outlet. Now I am confused about some values of the boundary conditions and do not know whether they are set correctly.
For the entrance, the Gauge Total Pressure is 201325pa, but for Supersonic/Initial Gauge Pressure, I am not quite sure how much to set.
For exports, the Gauge Total Pressure is 101325pa

[LuckyTran]

BC's look ok.
The supersonic static pressure is only required if the inlet is supersonic. Since your inlet is not supersonic, you do not have to worry.
Just to further explain, if the inlet becomes supersonic then you must specify stagnation and static pressure. For a subsonic inlet, you only need to specify stagnation pressure.

[lb0331]

Originally Posted by LuckyTran

BC's look ok.
The supersonic static pressure is only required if the inlet is supersonic. Since your inlet is not supersonic, you do not have to worry.
Just to further explain, if the inlet becomes supersonic then you must specify stagnation and static pressure. For a subsonic inlet, you only need to specify stagnation pressure.

thank you for your reply