View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0003845 | OpenFOAM | Bug | public | 2022-05-30 21:35 | 2022-05-31 19:37 |
| Reporter | mturcios777 | Assigned To | henry | ||
| Priority | none | Severity | minor | Reproducibility | always |
| Status | closed | Resolution | no change required | ||
| Platform | x64 | OS | Ubuntu | OS Version | 20.03 |
| Fixed in Version | dev | ||||
| Summary | 0003845: Mass conservation with engineFoam, cyclic boundary conditions and mesh motion | ||||
| Description | When using mesh motion classes from engineMesh (layeredEngineMesh, fvMotionSolver) and cyclic boundary conditions, engineFoam does not conserve mass. When the domain is closed has a small drift in mass but not to the extent as cyclic boundaries do. Using the static engine mesh class also conserves mass. | ||||
| Steps To Reproduce | 1. Download included case 2. Extract and go to workDir folder 3. Run engineFoam. Function objects have been included for flux through cyclics and total mass. | ||||
| Additional Information | I am trying to update an old solver created in OF2.3.1, and using the same case setup and sprayEngineFoam has no issues with mass conservation. I know that OpenFOAM 8 updated how cyclic transforms are calculated, so its possible there is a configuration flag we are missing. | ||||
| Tags | No tags attached. | ||||
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The layer addition and removal is indeed non-conservative and will need a rewrite. The whole structure for mesh change is being rewritten in OpenFOAM-dev, much of it already complete but there is still more to do. For engine simulations we are implementing a run-time mesh-to-mesh mapping system rather than working on layer addition and removal but if you would like to sponsor the rewrite of this component please contact us directly. |
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Thank you Henry. This is not the layer addition and removal, but the standard accordion style mesh that scales points below deckHeight and above the piston bowl. $FOAM_SRC/engine/engineMesh/layeredEngineMesh What is strange is that having the cyclic boundary conditions is what causes the mass divergence to grow beyond an acceptable limit. |
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It is not clear what is wrong with your case, we have not seen any conservation issues relating to cyclic boundary conditions. We could work on your case for you within a support contract. |
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Just did a quick test with OpenFOAM v8, which means that there was an issue when moving from 8 to 9 that caused issues. Will see if any patches fix the issue and consult with the community |
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Could you prepare a case for dev version so I could test this as well. Have you ruled out numerics based errors, i.e. you have ensured that pressure-momentum decoupling does not take place in this test case? |
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I saw similar behaviour (mass loss) in v9, switching to -dev solved the issue for me. Additionally, check that all your boundary conditions are correct. |
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Thanks peksa and cgneossni. I will upload a dev version soon. The engineFoam solver has been removed in favor of using reactingFoam and moving the mesh motion to the new fvMeshMovers library. @cgoessni, was your version 9 the most up to date from the git repository? I am using the source pack release and realize that it might not be the most up to date, as I had to manually patch the issue with engineTime not initializing the startTime properly and failing to write out the timesteps. |
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The boundary conditions are correct; cyclics defined appropriately and walls are: p: zeroGradient U: fixedValue, ( 0 0 0), except for the piston which is movingWallVelocity (0 0 0) |
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I honestly can't recall if it was v9 as released or a "new" v9, but I doubt it would make any difference. I would recommend just using -dev, since there were many other improvements in engine-related stuff, like mesh-to-mesh mapping, fvMeshMover interface and so on. |
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PS: Here is my bug report with the mass conservation issue https://bugs.openfoam.org/view.php?id=3782 |
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Thank cgoessni! So it looks like we were reporting the same issue. The mass loss in a closed domain was barely noticeable in our cases, but it was amplified by the cyclic boundary conditions. I guess this case can be closed, as dev is where everyone is going these days (I've been away from OF for a while and am getting used to a lot of changes) |
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Assumed to be fixed in OpenFOAM-dev but the case has not been updated or tested. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2022-05-30 21:35 | mturcios777 | New Issue | |
| 2022-05-30 21:35 | mturcios777 | File Added: aachenEngineFluxTest_cyclic_engineFoam.tar.gz | |
| 2022-05-30 23:10 | henry | Note Added: 0012607 | |
| 2022-05-30 23:10 | henry | Priority | immediate => none |
| 2022-05-30 23:10 | henry | Severity | major => minor |
| 2022-05-30 23:26 | mturcios777 | Note Added: 0012608 | |
| 2022-05-31 00:12 | henry | Note Added: 0012609 | |
| 2022-05-31 01:50 | mturcios777 | Note Added: 0012610 | |
| 2022-05-31 07:29 | peksa | Note Added: 0012611 | |
| 2022-05-31 07:41 | cgoessni | Note Added: 0012612 | |
| 2022-05-31 17:27 | mturcios777 | Note Added: 0012618 | |
| 2022-05-31 17:29 | mturcios777 | Note Added: 0012619 | |
| 2022-05-31 18:16 | cgoessni | Note Added: 0012620 | |
| 2022-05-31 18:18 | cgoessni | Note Added: 0012621 | |
| 2022-05-31 18:29 | mturcios777 | Note Added: 0012622 | |
| 2022-05-31 19:37 | henry | Assigned To | => henry |
| 2022-05-31 19:37 | henry | Status | new => closed |
| 2022-05-31 19:37 | henry | Resolution | open => no change required |
| 2022-05-31 19:37 | henry | Fixed in Version | => dev |
| 2022-05-31 19:37 | henry | Note Added: 0012623 |
