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Compressed Air filling in near vacuum chamber

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Old   May 6, 2017, 11:55
Default Compressed Air filling in near vacuum chamber
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Bharatvaaj
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The flow is a compressible flow and I have the pressure, mass and temperature (or density changes) variation with respect to each time step and I want this varying property to be initialized at the inlet through out the run time.

The original simulation is to capture how the air flows from a 0.6 L container at 21 bar(a),300K to 20L spherical container. Since, I am not able to close the valve at the end of 45 milli seconds and the simulation has to run for 60 ms and the feeding phase is shorter, I modeled the inputs of air and got the time varying functions assuming isentropic expansion.

I am not able to reach the desired end point where the air at the end of 60 ms is at 1 atm and 300 K inside the 20L sphere.

It is a compressible, transient flow. Later I will be adding particles to it.

Questions:

1) If I want to simulate the pressurized container, how to mimic the valve action ?
2) If I model the air flow inlet without the container, how do I initialize properly. Since i have all inlet data how to initialize everything with UDF or transient profile (I tried profile but not reaching the final solution).
3) How to let Fluent know that the final boundary conditions are 1 atm and 300 K iniside the entire zone of spherical chamber?

Pictorial representation of mesh and the simulation conditions are in this link. I m not able to post image here!

https://ibb.co/dEQCgQ
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Old   May 6, 2017, 15:57
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Filippo Maria Denaro
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Quote:
Originally Posted by Vaaj View Post
The flow is a compressible flow and I have the pressure, mass and temperature (or density changes) variation with respect to each time step and I want this varying property to be initialized at the inlet through out the run time.

The original simulation is to capture how the air flows from a 0.6 L container at 21 bar(a),300K to 20L spherical container. Since, I am not able to close the valve at the end of 45 milli seconds and the simulation has to run for 60 ms and the feeding phase is shorter, I modeled the inputs of air and got the time varying functions assuming isentropic expansion.

I am not able to reach the desired end point where the air at the end of 60 ms is at 1 atm and 300 K inside the 20L sphere.

It is a compressible, transient flow. Later I will be adding particles to it.

Questions:

1) If I want to simulate the pressurized container, how to mimic the valve action ?
2) If I model the air flow inlet without the container, how do I initialize properly. Since i have all inlet data how to initialize everything with UDF or transient profile (I tried profile but not reaching the final solution).
3) How to let Fluent know that the final boundary conditions are 1 atm and 300 K iniside the entire zone of spherical chamber?

Pictorial representation of mesh and the simulation conditions are in this link. I m not able to post image here!

https://ibb.co/dEQCgQ

That is not a boundary condition... you would impose that the numerical solution at a certain time has to reach such a homogeneous condition for the flow. Actually, you cannot set that, it is a result of your flow evolution...
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compressible flow, initialization, mass flow inlet confusion, transient compressible, vacuum chamber

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