How to ensure good cells with dynamic mesh motion?

petr.f. · February 20, 2015, 11:50

Nice Friday evening to all!

I've quite trivial question, which is however haunting me for the last month. I'm trying to solve several problems with dynamic meshes (motion of a wing, motion of a swimmers hand...) and so far every time the simulation has come to a moment, when the mesh gets distorted above acceptable level and computation diverges (using pimpleDyMFoam). I have tried time steps as small as 1e-7 (with flow velocities ~ 0 m/s) but it doesn't help. Still, I've seen simulations in OpenFOAM with much more difficult motions...

Is there some general rule of thumb concerning solver and overall settings for dynamic mesh simulations that minimizes bad mesh distortion?

Thanks,

P.

pbachant · December 27, 2016, 11:40

I have had similar issues as well. If you run checkMesh you can generate faceSets and cellSets to show the problem areas. I think a possible solution may be to remove cell layers when they become too compressed or stretched, but I'm not quite sure how to do that yet.

Some further reading:

https://ilyasivkov.wordpress.com/201...h-in-openfoam/

February 20, 2015, 11:50	How to ensure good cells with dynamic mesh motion?	#1
petr.f. Member Petr Furmanek Join Date: Jan 2012 Location: Faenza, Italy Posts: 66 Rep Power: 14	Nice Friday evening to all! I've quite trivial question, which is however haunting me for the last month. I'm trying to solve several problems with dynamic meshes (motion of a wing, motion of a swimmers hand...) and so far every time the simulation has come to a moment, when the mesh gets distorted above acceptable level and computation diverges (using pimpleDyMFoam). I have tried time steps as small as 1e-7 (with flow velocities ~ 0 m/s) but it doesn't help. Still, I've seen simulations in OpenFOAM with much more difficult motions... Is there some general rule of thumb concerning solver and overall settings for dynamic mesh simulations that minimizes bad mesh distortion? Thanks, P.

December 27, 2016, 11:40		#2
pbachant Senior Member Pete Bachant Join Date: Jun 2012 Location: Boston, MA Posts: 173 Rep Power: 13	I have had similar issues as well. If you run checkMesh you can generate faceSets and cellSets to show the problem areas. I think a possible solution may be to remove cell layers when they become too compressed or stretched, but I'm not quite sure how to do that yet. Some further reading: https://ilyasivkov.wordpress.com/201...h-in-openfoam/ __________________ Home \| Twitter \| GitHub

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