[chisoph]

Hello my friends,

I'm new in OpenFoam and I'm now working 3 months on this problem and I can't find a solution for my problem in the web. So I thought I ask the elite of OpenFoam.

I would like to simulate the Joule-Thomson effect in a pipe with a sudden expansion because of a diameter change of the pipe. The simulation starts and runs till it reaches the outlet. Then suddenly the simulation crashes. The picture shows you the last step of the simulation before it crashes. I really tried to solve the problem by my own, but I have no further idea....

Attached you can find my case setup.

I use
Solver: rhoPimpleFoam
Mesh: 2D-3D makeAxialMesh
sutherland transport
janaf thermo
PengRobinsonGas equation of State

If you need more information please don't hesitate to ask.

Thanks for your help

chisoph

[user_of_cfx]

I think one piece of additional information which would help would be your simulation log, so people can see the error you are getting and what led up to it.

I am no expert by any means, but I noticed you are using a very small number of iterations in fvSolution: nOuterCorrectors 1; It may be you have convergence issues because of this? I would increase that number by a lot, maybe above 250 or even higher. Then you can monitor the cumulative error in the log to check that it does not increase too much as then the simulation will crash.

Also, what is your velocity doing? Does it reach Mach = 1 at any point? if so maybe sonicFoam is a better solver for this? Again, no expert, this is just an idea.

Btw is this J-T cooling or heating you're modelling? because the T fluctuation all the way from 200 K up to 800-odd K is strange for gas expansion starting at 295K. Not sure if this is physically possible. So I am inclined to think that either a. your simulation does not converge or b. your thermo properties may not be correct to capture J-T.

One final thing, you have not fixed the pressure anywhere in your system?

Cheers,

Christa

[chisoph]

Hi Christa,

Thank you very much for helping me.

Attached you can find the last entries of the Simulation Log. The Warnings based on JANAF also appear at the beginning of the Simulation. This Warnings don't lead to the crash I think.

I will try to increase the nOuterCorrectos next time.

Yes I do reach Mach > 1. As I said, I'm new in OpenFoam and I thought rhoPimpleFoam sounds like it could work. But I will try it using the SonicFoam Solver.

The gas expansion should lead to a Joule-Thomson cooling. I have no idea where those high values in the temperature come from.

What do you mean with fixing the pressure? The inletflow is controlled over the velocity. Relating to this velocity, the pressure is calculated. I want to simulate the effect of Joule-Thomson in a laminar, a laminar-turbulent-transition and a turbulent flow. Thats why I want to control the simulation over the velocity.

Thanks,

greets chisoph

[Ahmedshoeb]

Hello chisoph,

Have you found a solution to your problem ?
i am also working on simulating the Joule Thompson effect and i am having some troubles setting up the case.

[mm66]

Hi Foamers,

Any recommendations for the solver? I am having a hard time finding a suitable solver for the refrigerant expansion with the JT effect... Any help is very much appreciated.

Cheers,
MJ