pressure spikes due to addition/deletion of layers
I was running icoDyMFoam on the tutorial case movingConeTopo. I added one line to icoDyMFoam to write out the maximum pressure in the domain at every time step. I found that almost every time there is a cell addition/deletion, there is a pressure spike in the domain. Has anyone else seen these spikes? and has anyone found a solution?
Which version are you using? The implementation of the movingCone(or Body)TopoMesh is altered in later revisions of the 1.6-ext version. In the newer (and parallel) version, a lot of lines are commented out in Foam::movingBodyTopoFvMesh::update() . These lines affects how meshPhi (in fvc::makeAbsolute(phi, U) and fvc::makeRelative(phi, U)) is determined (if I understood correctly). If meshPhi is wrong, I would guess it could result in pressure peaks. Do you have any possibility to repeat your check on a previous, non-parallel version of the movingCone/Body case?
Thanks for your post. We updated to the latest version of 1.6-ext to see what difference it made, and we found that the spikes were considerably smaller, but still existed.
if you/ anyone else would like to test this, you can just add the following functionObject to the controlDict and run the movingConeTopo test case with icoDyMFoam.
Thanks a lot for your help
Thank you for bringing this up. I tried the case, and there are spikes as you say. Pressure is initially fluctuating around ~4e-4 to ~1e-4 as layerAR is working. I tried a few modifications to the movingBodyTopoFvMesh-class without success. Right now I do not have any clue how to get on. To solve this issue, I think one should find out how this adding layer functionality is handled within the finite volume method. This paper may provide some help:
http://web.univ-ubs.fr/limatb/EG2M/D...pers/01178.pdf see especially section 2.3
I also need to fix this for my own work, so I will likely get back to it when I have time.
Thanks for looking into this and thanks for the paper. Please let me know if you find anything.
I can see this thread is quite old, but I would like to know if this problem was ever resolved?
I am having the same issue but with pimpleDyMFoam with layer addition/removal and translation (foam-extend 3.1). I have tried to resolve this by mostly messing around with the following settings, but with no real success:
nCorrectors - increase
nNonOrthogonalCorrectors - increase
nOuterCorrectors - increase
relaxation factor for pressure - reduce
use of smoother & preconditioner with solver
minimum layer thickness in dynamicMeshDict - increase
Gauss upwind for div schemes and Guess linear limited for laplacian schemes zeroGradient for all pressures at boundary patches
relTol for all solvers set to 0
Any advice would be greatly appreciated
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