Closed domain compressible flow simulation

Vaaj · May 6, 2017, 11:52

You are the one I find responding quickly, that is why pestering you. Sorry.

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!

I will create a thread too.

https://ibb.co/dEQCgQ

The new thread is here

https://www.cfd-online.com/Forums/ma...tml#post647897

Thanks man.

ghorrocks · May 7, 2017, 07:39

I have no problem in being pestered, the forum is here to ask questions. But please start a new thread for a new question - so I have moved this post to a new thread. I have also moved this to the fluent forum as your question is about fluent.

Why can't you close the valve at 45ms? What valve are you talking about anyway?

Vaaj · May 7, 2017, 20:38

I have not designed a valve. In the picture on the right in the link has two containers. The air flow from bottom one to the top one and it has to stop at 45 ms and I am not able to stop it. So I made a mesh thats on the left and modeled the air input that varies with time.

But it is not reaching the final expected solution.

May 6, 2017, 11:52	Closed domain compressible flow simulation	#1
Vaaj New Member Bharatvaaj Join Date: Feb 2017 Posts: 23 Rep Power: 9	You are the one I find responding quickly, that is why pestering you. Sorry. 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! I will create a thread too. https://ibb.co/dEQCgQ The new thread is here https://www.cfd-online.com/Forums/ma...tml#post647897 Thanks man.

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May 7, 2017, 07:39		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	I have no problem in being pestered, the forum is here to ask questions. But please start a new thread for a new question - so I have moved this post to a new thread. I have also moved this to the fluent forum as your question is about fluent. Why can't you close the valve at 45ms? What valve are you talking about anyway?

May 7, 2017, 20:38		#3
Vaaj New Member Bharatvaaj Join Date: Feb 2017 Posts: 23 Rep Power: 9	I have not designed a valve. In the picture on the right in the link has two containers. The air flow from bottom one to the top one and it has to stop at 45 ms and I am not able to stop it. So I made a mesh thats on the left and modeled the air input that varies with time. But it is not reaching the final expected solution.