View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0001468 | OpenFOAM | Bug | public | 2014-12-25 10:18 | 2015-05-01 00:49 |
| Reporter | Assigned To | henry | |||
| Priority | high | Severity | crash | Reproducibility | always |
| Status | resolved | Resolution | fixed | ||
| Platform | Desktop and Cluster | OS | Linux Mint / SUSE | OS Version | 17 / Enterprise |
| Summary | 0001468: Something wrong in the CrankNicolson ddt scheme (2.3.x) | ||||
| Description | When running LES calculation on 2.3.x with CrankNicolson ddt scheme, maximum courant number gradually increases and finally calculation blows. I cannot see the problem with backward ddt scheme or CrankNicolson in "2.2.x". So, I can guess any changes between 2.2.x and 2.3.x causes the problem. In addition, I have been faced with the problem since 2.3.0 released. So, It might not be caused by recent commitment. | ||||
| Steps To Reproduce | Running tutorial case (pisoFoam/pitzDaily) with: ddtSchemes { default CrankNicolson 1; } Initial residuals of each velocity component remains higher (near 0.9) and courant number starts weaving. Finally, calculation will stop at Time=0.02656 (in my case). | ||||
| Tags | No tags attached. | ||||
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Thanks for the report. In OpenFOAM-2.3.? I changed ddtCorr to handle mesh-motion in a more general way, accurately including the effects of face rotation as well as translation. However, it was not clear that this approach needed the Crank-Nicolson corrections and tests showed that the Euler ddtCorr handling was sufficient for the Crank-Nicolson scheme. But these tests were done using a small amount of off-centering: default CrankNicolson 0.9; which has been found necessary in order to stabilize this scheme for complex flows, providing similar accuracy and stability as the backward scheme. I have now run tests without off-centering as you are running and also find that for cases where this is stable in OpenFOAM-2.2.x it is not stable in OpenFOAM-2.3.x, unless the Crank-Nicolson corrections to ddtCorr are reinstated. I have now pushed this change to OpenFOAM-2.3.x. Resolved by commit 9a79633f0723bd714aa25f3eec21e4d90623ee90 |
