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OpenFOAM v2312 - Centrifugal Pump case with StarCCM+polymesh |
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#1 | |
New Member
Join Date: Jul 2024
Posts: 7
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Dear OpenFOAMers,
As an OpenFOAM newbie I do solicit your help for an OpenFOAM case setting. I work on OpenFOAMv2312 (OpenFOAM.com) and try to set a centrifugal pump case from a polymesh generated from StarCCM+. Here is the setting based on the tutorial Mixer2D. Solver: pimpleFOAM Mesh: 3 regions (Inlet, impeller and volute) Turbulence: Laminar (no turbulence for the moment only momentum and pressure)
N.B. A scotch method is applied to use decomposePar Quote:
It automatically diverges. Courant number value quickly "explodes".U and P iterates more than 1000 times. It seems the AMI interfaces work well and the rotation too. But I still do not understand why it diverges. If I set runTimeModifiable as true and adjustTimeStep as yes it iterates to keep the courant number under 5 (the value I set) but the deltaT quickly decreases down to 1e-11 s. Is there any subtlety I miss to perform the computation case? Do you know how to increase iteration with a minimum of 5 per time step? Thank you in advance for your help Last edited by CFD_SG_01; July 17, 2024 at 11:22. |
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#2 |
New Member
Join Date: Jul 2024
Posts: 7
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Hello,
I keep moving forward on this case and I've finally found what the was the initial problem. The issue came from the mesh. It seems like openFOAM solver is not as robust as StarCCM+ solver. There were few cells with a wrong aspect ratio. I keep trying to work on the case and today I find some very high velocity values close to the impeller/volute AMI face zone. Is there any subtlety to set to avoid such numerical aberration? Thank you in advance for your help ![]() |
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#3 | |
New Member
Join Date: Jul 2024
Posts: 7
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Hello,
Here are the latest news regarding the case I try to set. The case seems to work weel when I use simpleFoam solver combine with the MRF method but it is still extremely difficult to compute it using pimpleFoam with slidingMesh method. The courant number explodes as well as the maximum U magnitude value (see below the terminal extraction) Quote:
Thank you in advance for your help |
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#4 |
Senior Member
Yann
Join Date: Apr 2012
Location: France
Posts: 1,169
Rep Power: 27 ![]() |
Hello,
Have you checked where you get these high velocities? Is it still in the vicinity of the AMI interfaces? You may have a look to you log file and check what you get on AMI: Code:
AMI: Creating AMI for source:AMI1 and target:AMI2 AMI: Patch source faces: 96 AMI: Patch target faces: 96 AMI: distributed AMI: Patch source sum(weights) min:1.00007 max:1.00007 average:1.00007 AMI: Patch target sum(weights) min:1.00007 max:1.00007 average:1.00007 You can try using the moveDynamicMesh utility. This will allow to move the mesh without solving the flow. It can be useful to check if your mesh is moving as expected and if there is no issue at the interface (such as deformed or overlapping cells during the mesh motion due to wrong AMI definition) There is also a -checkAMI option with this utility to write VTK files of the interfaces with the corresponding weights. If there is something wrong with the AMI it can also be helpful to see where the problem lies. Regards, Yann |
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