[snappyHexMesh] SnappyHexMesh issue with face pyramid volume

EricS · December 31, 2021, 03:59

Hi everybody,

I'm quite a new user to OpenFOAM and I've been fighting for a couple weeks now with the creation of the mesh for a complex geometry.. every time I try to do it, with a lot of settings' tests, I keep reading that, after all the iterations both in the castellation and snapping, I still have some "faces with pyramid volume < 1e-3".
I was wondering, how can I improve that? Because I think that causes my solution to diverge at a certain point.

Thank you in advance!

Regards,
Eric

ghastbug · February 19, 2022, 10:49

I'm pretty sure the standard pyramid volume thresholds is about e-13, so you could lower it maybe.

From what I could understand, the pyramid volumen threshold is what it sounds like, a warning to tell you if a cell is smaller than that. So if you designed your mesh to have cells smaller than that volume, then you should lower it. However, if you have designed your mesh for your cells to be an order of magnitude higher, and it triggers, then some of your cells are messed up

December 31, 2021, 03:59	SnappyHexMesh issue with face pyramid volume	#1
EricS Member Eric Segalerba Join Date: Dec 2021 Location: Italy Posts: 31 Rep Power: 5	Hi everybody, I'm quite a new user to OpenFOAM and I've been fighting for a couple weeks now with the creation of the mesh for a complex geometry.. every time I try to do it, with a lot of settings' tests, I keep reading that, after all the iterations both in the castellation and snapping, I still have some "faces with pyramid volume < 1e-3". I was wondering, how can I improve that? Because I think that causes my solution to diverge at a certain point. Thank you in advance! Regards, Eric

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February 19, 2022, 10:49		#2
ghastbug Member Join Date: Mar 2018 Posts: 33 Rep Power: 8	I'm pretty sure the standard pyramid volume thresholds is about e-13, so you could lower it maybe. From what I could understand, the pyramid volumen threshold is what it sounds like, a warning to tell you if a cell is smaller than that. So if you designed your mesh to have cells smaller than that volume, then you should lower it. However, if you have designed your mesh for your cells to be an order of magnitude higher, and it triggers, then some of your cells are messed up