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January 15, 2019, 05:34 |
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#21 | |
Senior Member
Kevin van As
Join Date: Sep 2014
Location: TU Delft, The Netherlands
Posts: 252
Rep Power: 20 |
Quote:
What remains is the question "why use more than one iteration": That's to make sure that your system of equations are solved properly. Within one outer/SIMPLE iteration, the alpha/VOF equation would only be solved once using the old pressure and velocity fields. (Evidently, pressure and velocity are already being iterated using the inner/PISO iterations.) To correctly solve for the entire system of equations, you'd thus need to iterate, don't you? If I combine what you said with what I think to be true, then one should use little outer/SIMPLE iterations together with no relaxation for the best result? (Unless relaxation is needed, because the mesh is poor / system is ill-posed / etc., for which the system needs stabilisation.) |
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February 27, 2019, 19:03 |
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#22 |
New Member
Join Date: Aug 2018
Posts: 9
Rep Power: 7 |
Thank you for the response Joaran. How have people learned to use PIMPLE correctly before Tobias Holzmann's publication? It's surprising to me that the usage explained by Dr. Holzmann is not a template in any of the OpenFOAM tutorials. Perhaps this is an artifact of OpenFOAM being open-source code. I have even found that it is not applicable to some of the PIMPLE-related solvers like heatTransfer/chtMultiRegionFoam (though I guess they are just outdated). I would like to better understand the context behind this correct usage (i.e., using residual controls, setting the number of outer loops to some high value). Also, are there other sources that describe strategies for configuring the settings? Many thanks for your attention. -Mimi
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February 28, 2019, 06:44 |
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#23 | |
New Member
Joaquín Aranciaga
Join Date: Oct 2018
Posts: 21
Rep Power: 7 |
Quote:
I actually haven't found any better information about the configuration of fvSolution than Holzmann's book. I think that the best way to learn to use OpenFOAM is playing with it, making mistakes, and search in this forum and/or googling your errors to find an answer. I suppose though it'd be better to take a course, if you can afford it. And ultimately all the information is contained in the installation files, be it a comment, or a program line, so I'd recommend you try to learn how to read the files and make an effort to understand what the main lines do. For that, it's a really good idea to spend some time taking a tutorial on C++. Sorry for not being such a help, this was just my (tiny) experience using OpenFOAM. Joa |
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January 15, 2020, 15:51 |
Slow simulation
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#24 |
New Member
Aditya Srivastava
Join Date: Sep 2019
Posts: 1
Rep Power: 0 |
I am also simulting rising bubble in interfoam. The mesh is very refined as of size D/40 where D is diameter of bubble. The p_rgh is taking 1000 iteration to converge which is slowing my simulation. Kindly suggest what to do
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December 2, 2021, 09:38 |
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#25 |
New Member
Join Date: Jun 2017
Posts: 14
Rep Power: 8 |
how to remove message?!
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December 2, 2021, 09:40 |
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#26 | |
New Member
Join Date: Jun 2017
Posts: 14
Rep Power: 8 |
tatadocomo,
this helped me to reduce p_rgh iterations: Quote:
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pimple |
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