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Re: Divergence for simple geometry room
Posted: Thu Jul 15, 2021 8:42 pm
by Yvan Fournier
Hello,
Sorry, I did not have the time to test the case yet. I'll let you know as soon as I run it.
Best regards,
Yvan
Re: Divergence for simple geometry room
Posted: Fri Jul 16, 2021 8:01 pm
by Tsubasa
Hello,
Ok, Thanks.
Even in steady simulation, divergence problem happned.
Best regards,
Hamada
Re: Divergence for simple geometry room
Posted: Mon Jul 19, 2021 1:47 pm
by Yvan Fournier
Hello,
Changing the outlet to "imposed pressure outlet" alone was not sufficient, but switching to least-squares gradient reconstruction with full extended neighborhood, I can run 500 iterations just fine (tested with v7.0).
Best regards,
Yvan
Re: Divergence for simple geometry room
Posted: Mon Jul 19, 2021 6:39 pm
by Tsubasa
Hello,
Thank you for the test.
I am grad to hear that steady simulation can be done by steady simulation.
Also how about unsteady case?
Do you think it can be done with Ver.6?
Finally I want to do pressure-driven flow by SRC code, but now the simulation has a divergenec problem with Ver.6.
Best regards,
Tsubasa
Re: Divergence for simple geometry room
Posted: Mon Jul 19, 2021 8:03 pm
by Yvan Fournier
Hello,
I actually ran the test for an unsteady flow (as your setup.xml was set for unsteady, constant time step).
This should probably also work in v6.0, though I recommend upgrading to v7.0.
Pressure driven flow should work, but may be a bit more sensitive. Increasing the pressure difference progressively (using a ramp type function) rather than all at once might help.
Best regards,
Yvan
Re: Divergence for simple geometry room
Posted: Mon Jul 19, 2021 10:28 pm
by Tsubasa
Hello,
Thanks a lot.
At first, I will build Ver.7 and do the test with it.
Best regards,
Tsubasa
Re: Divergence for simple geometry room
Posted: Mon Jul 19, 2021 11:34 pm
by Tsubasa
Hello Yvan,
In the previou post, you said "least-squares gradient reconstruction with full extended neighborhood".
Is this same to "least squares method over extended cell neighborhood" in Ver.6?
Best regards,
Tsubasa
Re: Divergence for simple geometry room
Posted: Tue Jul 20, 2021 12:25 am
by Yvan Fournier
Hello,
Yes, it is the same.
Best regards,
Yvan
Re: Divergence for simple geometry room
Posted: Tue Jul 20, 2021 12:30 am
by Tsubasa
Hello Yvan,
As you said, a simulation can be done by "least squares method over extended cell neighborhood" in Ver.6,
but the pressure difference flow simulation had a divergence problem.
In my case, pressure difference is just 0.6Pa. This is very small, but the result became divergent.
Best regards,
Tsubasa
Re: Divergence for simple geometry room
Posted: Thu Jul 29, 2021 12:26 am
by Tsubasa
Hello Yvan,
Do you think Ver.7 is more stable for computation than Ver.6?
(Idealy, I want to conduct a pressure driven flow by steady simulation (not URANS).)
If you think so, I want to try it with Ver.7.
If it is possible, every problem can be solved, which is posted in another post.
Best regards,
Tsubasa