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how can I make sure rhoSimplecFoam NEVER crashes? |
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September 21, 2012, 17:10 |
how can I make sure rhoSimplecFoam NEVER crashes?
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#1 |
Senior Member
Mihai Pruna
Join Date: Apr 2010
Location: Boston
Posts: 195
Rep Power: 16 |
Basically I want it to automatically cut off big numbers, replace divisions by 0 with something else, etc.
I tried relaxation factors and cellLimited gradients. Is there a way to ensure you get a solution (even inaccurate) , always? |
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December 25, 2012, 22:55 |
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#2 |
Member
Haomin Yuan
Join Date: Jan 2012
Location: Madison, Wisconsin, USA
Posts: 59
Rep Power: 14 |
Hi, Mihai
Have you solved your problem, I think I have met the same problem like you. I am running a simulation with a large area change, which makes the simulation very easy to crash. Thank you |
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December 27, 2012, 09:12 |
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#3 |
Senior Member
Mihai Pruna
Join Date: Apr 2010
Location: Boston
Posts: 195
Rep Power: 16 |
I had to streamline the geometry further. I was not able to get it to converge on my original model. WIth that, and residuals set to 10E-3, I was able to get it to converge. I had to set residuals this high because divergence occurred after a certain number of iterations. The residuals dropped to a certain level and then they started increasing (p mainly), and then the density would eventually reach either very large or small values, then it would crash.
So, in essence, I have not found a simple solution or a setting that would always ensure convergence just yet. |
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December 27, 2012, 09:31 |
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#4 |
Member
Haomin Yuan
Join Date: Jan 2012
Location: Madison, Wisconsin, USA
Posts: 59
Rep Power: 14 |
Is your flow a pressure driven flow or velocity driven flow? I think you can try time varying condition to get approach the condition you want. And I also suggest you try to decrease the relaxation factor to ensure stable.
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December 27, 2012, 11:10 |
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#5 |
Senior Member
Mihai Pruna
Join Date: Apr 2010
Location: Boston
Posts: 195
Rep Power: 16 |
I decided to go with pressure driven flow (total pressure).
In order to prevent my simulation from crashing right away , I had , for the inlet: type totalPressure; gamma 1.400000; rho rho; p0 uniform 29400.000000; value uniform 26500.000000; the 26500 was the static pressure and that was set to fixed at the outlet. I was not able to get the flow to a Mach number above 0.4 without it eventually crashing. Relaxation factors helped a bit. So, again, it was a combination of factors and tweaks of residuals, relaxation factors, geometry and boundary conditions that yielded a converged solution. |
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