View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000139 | OpenFOAM | Bug | public | 2011-02-15 15:06 | 2011-07-28 15:36 |
| Reporter | Assigned To | administrator | |||
| Priority | normal | Severity | major | Reproducibility | always |
| Status | resolved | Resolution | fixed | ||
| Summary | 0000139: Wrong courant number calculation for boundary patches | ||||
| Description | Hi, I'm not sure if this has been discussed before, or is a case of "works as designed", but here we go: For my private interFoam-variant I recognized that the calculated timestep length is often smaller than expected from the CFL-criterion. I boiled it down to the point that $FOAM_SRC/finiteVolume/cfdTools/incompressible/CourantNo.H (and its variants) give back wrong values if faces at inlet/outlet-patches have "high" velocities. The reason for this that mesh.surfaceInterpolation::deltaCoeffs() should return the cell-to-cell distance for a face, but for faces at boundaries it returns face-to-cell distance instead, roughly half of it. This o.k., but as a consequence the computed CFL-number is (wrongly) twice as high as expected. Thus, either boundary faces should be excluded from the CFL-computation or the "distance" should be doubled. Bye, Carsten | ||||
| Steps To Reproduce | Run the attached example with interFoam. It has a 1m x 1m x 1m grid spacing. Velocity is 1m/s. Timestep length should be adjusted to CFL=1. Expected result: Timestep length = 1.0 s Observed result: Timestep length = 0.5 s | ||||
| Tags | No tags attached. | ||||
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2011-02-15 15:06
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Thanks for the detailed report. This is a known problem and we have developed more reliable ways to evaluate the effective Courant number resolving this and other potential problems with the current approach. These new methods will be included in our next release of OpenFOAM. |
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Hello Henry, is there already a scheduled date for the next version? Or a simple workaround you would suggest (a way to manipulate CourantNo.H so that boundary patches are ignored?)?. Thanks, Carsten |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2011-02-15 15:06 |
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New Issue | |
| 2011-02-15 15:06 |
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File Added: couranttest.zip | |
| 2011-02-15 15:24 | henry | Note Added: 0000248 | |
| 2011-02-15 15:24 | henry | Assigned To | => henry |
| 2011-02-15 15:24 | henry | Status | new => acknowledged |
| 2011-02-15 15:33 |
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Note Added: 0000249 | |
| 2011-07-28 15:36 |
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Status | acknowledged => resolved |
| 2011-07-28 15:36 |
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Resolution | open => fixed |
| 2011-07-28 15:36 |
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Assigned To | henry => administrator |
