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|ID||Project||Category||View Status||Date Submitted||Last Update|
|0002162||OpenFOAM||Bug||public||2016-07-28 14:03||2018-02-07 11:08|
|Summary||0002162: Wrong behaviour of interDyMFoam with dynamic Mesh|
|Description||Since version 4.0 interDyMFoam seems to do wrong in combination with dynamicMesh cases. I compared floatingObject tutorial with 3.0.x, results are very different. Both the motion and the free surface elevation. Results of interFoam solvers in 3.0.x and 4.x are the same. interDyMFoam with staticFvMesh agrees with interFoam, therefore it seems to be linked to dynamicFvMesh. (see attached snapshots from first timesteps of floatingObject simulations)|
Also interesting: For the DTCHull tutorial, when running in PISO-Mode (nOuter=1) the solvers give same results in Version 3.0.x and 4.x
|Tags||No tags attached.|
floatingObject.pdf (440,864 bytes)
In OpenFOAM-4.x the floatingObject case is setup to demonstrate the new n-DoF motion solver. In the constant directory you will see dynamicMeshDict and dynamicMeshDict.sixDoF, if you
mv dynamicMeshDict.sixDoF dynamicMeshDict
then it will run the same setup as OpenFOAM-3.0.x
If have done simulations with both, new n-DoF motion solver and old sixDoFRigidBodyMotion solver in 4.x. They both deliver almost same results, but differ to results from 3.0.x., see attached graph of linear velocity vs time.
Therefore I am quite sure, it is not linked to the sixDoF implementation.
After some more investigation of the floatingObject tutorial, it seems the differences are due to the Crank-Nicolson time integration.
With offcentering 0, i.e. pure Euler the results of OpenFOAM-3.0.x and OpenFOAM-4.x are absolutely identical, but differs strongly when using Crank-Nicolson 0.9 (default in tutorial). See attached plot floatingObject_eulerCN.gif
Maybe phi.oldTime() is not working as it should?
||Thanks for your effort and detailed analysis. I have now found the issue and testing a fix. I will push the update to OpenFOAM-4.x and OpenFOAM-dev shortly.|
Resolved in OpenFOAM-dev by commit aa7b3dfe7dfc02ce104a7cf9c5b0b5b49c3f31df
Resolved in OpenFOAM-4.x by commit 62dd439d9cbf20aa50a11ab035818eecc95d6c61
Please reopen if you see further problems.
|2016-07-28 14:03||jkau||New Issue|
|2016-07-28 14:03||jkau||File Added: floatingObject.pdf|
|2016-07-28 14:43||henry||Note Added: 0006577|
|2016-07-28 14:44||henry||Severity||major => minor|
|2016-07-28 14:59||jkau||File Added: floatingObject.gif|
|2016-07-28 15:01||jkau||Note Added: 0006578|
|2016-07-28 15:02||jkau||Note Edited: 0006578|
|2016-07-29 15:04||jkau||Note Added: 0006581|
|2016-07-29 15:05||jkau||File Added: floatingObject_eulerCN.gif|
|2016-07-29 15:05||jkau||Note Edited: 0006581|
|2016-07-29 15:07||jkau||Note Edited: 0006581|
|2016-07-29 15:59||jkau||Note Edited: 0006581|
|2016-07-29 16:35||henry||Note Added: 0006582|
|2016-07-29 17:55||henry||Note Added: 0006583|
|2016-07-29 17:55||henry||Status||new => resolved|
|2016-07-29 17:55||henry||Fixed in Version||=> 4.x|
|2016-07-29 17:55||henry||Resolution||open => fixed|
|2016-07-29 17:55||henry||Assigned To||=> henry|