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superarthur86 March 6, 2012 18:19

Need Help! High pressure Gas discharge from tank to tank through a pipe

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 April 2, 2012 14:58

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

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