[abduly85]

Hello all,
I'm trying to simulate the transient filling process of a compressed air tank.
It's a simple case, the shape is cylindrical (10cm diameter by 20cm deep cylinder with 1cm diameter inlet), initial tank pressure is atmospheric (14.7 psi) and inlet pressure at a constant 60 psi.
I'm having many errors when applying the "pressure-inlet" BC type at the inlet. I can get the simulation running if I apply a "velocity-inlet" BC type, however, my goal is to simulate the air mass flow rate based on the pressure difference between the initial tank pressure (14.7 psi) and the external pressure (60 psi).

What I've done so far:
1- 3D Geometry: Extruded 1/4 of the cylinder due to symmetry. The whole domain is fluid (air) with the inlet being a surface.
2- Meshed using ANSYS Mesher (mesh is coarse for now)
3- Fluent:
- Used density-based
- Turned the energy model on.
- Used the K-E model
- Density Air (materials) selected to be "Ideal Gas"
- BCs: Inlet selected as "pressure inlet" with 70 psi gauge pressure
- Solution Initialization: Since the initial pressure I want is 14.7 psi I selected "Standard Initialization" with 14.7 psi gauge pressure.
- Step size (for now) is 0.01 seconds.

Please let me know if you could help me, I appreciate it.

Regards