[superarthur86]

Hello,

I am a starter of fluent and I need to model the methane discharge/depletion from a high-pressure vessel to a low-pressure one through a thin long pipe. Choked flow is likely to happen.

The system is closed.
I wonder can anyone guide me to solve this problem. I am current doing my PhD and I am an experimental guy but I need to model this experiment via fluent in order to graduate.
Here is the problem description:
Initial pressure at the upstream tank: 2000psi.
Initial pressure at the downstream tank: 500psi.
Volume of the upstream tank: 1cc.
Volume of the downtream tank: 15cc.
length of the pipe: 8ft
Diameter of the pipe is 0.005in, which is 100 times smaller than the in/out ports of the tanks.
When t=0, the valve of the upstream tank open to let the gas deplete to the dowstream tank.
I need to simulate the pressure change with time in the downstream tank as well as modelling the flow propagation through the pipe.

Thank you very much.

[syavash]

dear Arthur,
first off you should model your geometry using some grid generation tool,e.g. Gambit. then you should take your geometry into Fluent. Since you haven't cleared I ask: Have you modeled the geometry?
When you read the geometry in Fluent, be careful about the dimension of your case (2-D or 3-D). Fluent initially asks you and you should select it carefully.
You mentioned you know the inlet/outlet pressure, so you should use Pressure-Inlet Boundary condition.
Since you are working with high pressure, you should select ideal-gas in material panel and in advance, select density-based solver in Solver panel and select unsteady mode in addition due to your problem is unsteady.

Good luck

[Ram Prakash]

Me to trying to solve same type of problem with propane leaking from a tank at 5 bar into a room containing air. And i want to have the propane as ideal so that its density changes with the pressure. Please help me to choose the model in which it should be done.