2d axisymmetric fluent transient simulation problem
 

Dear friends

I am currently trying to simulate a compressor tank releasing compressed air into a room with an opening over 1.5 seconds. I need to monitor the pressure in the compressor tank, the room pressure as well as the mass flow rate of the airflow coming out of the compressor tank.

I built 2D axisymmetric model to reduce the computation time. I patched initial pressure to the tank as 554600 Pascal (300K temperature) and set the operating pressure as atmosphere 101325 Pa. Time step is 0.0001 s, with 15000 time steps.

The problem I have encountered is the tank pressure stablised approximately at 552000 Pascal and not wanting to go down any more. Apparently, that is not right.

Using the same setting in 3D simulation and 2D symmetrical simulation, the pressure was fine. It only happened when I use axisymmetric model. I have never used axisymmetric before, and I am wondering if it is because I set it up incorrectly.

Your thoughts and suggestions would be much appreciated.

Thanks
Ken