[snappyHexMesh] Skewed cells after snap

998gp · April 8, 2021, 16:41

Hello,

After I complete SHM, there are 4 cells at the corners of the geometry that are always skewed. I would expect them to be unskewed since blockMesh creates them but for some reason they always show up. Any idea what could be causing this?

Thanks
P

AtoHM · April 9, 2021, 02:41

What tells you that they are skewed?

998gp · April 9, 2021, 10:20

Good point.

Maybe my question should have been what causes them to have that shape. The underlying surface mesh? Snap settings?

AtoHM · April 10, 2021, 13:14

You mean why are they not perfect cubes?
I do not know for sure, but, even if the background mesh covers that geometry 1:1 at that position, I can imagine there are still some minor deviations which causes the smoothing algorithm to slighty shift the nodes around. At least at the right side. Resolution of the used stl file could be a reason too, maybe.
At the left side, the first column of cells is obviously thinner than the ones next to it. So, I would guess the initial blockMesh was slightly bigger and then these cells were compressed a bit. However, all these cells are still near perfect, so nothing to worry about.

April 10, 2021, 13:14		#4
AtoHM Senior Member M Join Date: Dec 2017 Posts: 698 Rep Power: 12	You mean why are they not perfect cubes? I do not know for sure, but, even if the background mesh covers that geometry 1:1 at that position, I can imagine there are still some minor deviations which causes the smoothing algorithm to slighty shift the nodes around. At least at the right side. Resolution of the used stl file could be a reason too, maybe. At the left side, the first column of cells is obviously thinner than the ones next to it. So, I would guess the initial blockMesh was slightly bigger and then these cells were compressed a bit. However, all these cells are still near perfect, so nothing to worry about. Last edited by AtoHM; April 12, 2021 at 03:09.

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April 9, 2021, 02:41		#2
AtoHM Senior Member M Join Date: Dec 2017 Posts: 698 Rep Power: 12	What tells you that they are skewed?

April 9, 2021, 10:20		#3
998gp New Member Join Date: Dec 2020 Posts: 9 Rep Power: 5	Good point. Maybe my question should have been what causes them to have that shape. The underlying surface mesh? Snap settings?