[snappyHexMesh] orthogonal cells marked as nonOrthogonal

colinB · November 21, 2013, 08:30

Hi Foamers,

I have some troubles with cells which are marked as nonOrthogonal
but are according to my interpretation perfectly orthogonal.
checkMesh says maxOrth: 75.xxx with 10k cells in a mesh of 3.1M cells.
I'm using LTSInterfoam in a more or less simple channel flow with a ship.

The cells causing troubles are created with a refinementBox in sHM

If somebody could give me an explanation to that phenomena and maybe
an explanation on how I can avoid them, would be great.

See attached some pictures which should illustrate the problem:

NonOrthoFaces_1.jpg

NonOrthoFaces_2.jpg

NonOrthoFaces_3.jpg

NonOrthoFaces_5.jpg

NonOrthoFaces_7.jpg

If you have further questions or need more information let me know
regards
Colin

colinB · November 21, 2013, 08:31

some more pics:

NonOrthoFaces_8.jpg

NonOrthoFaces_9.jpg

thx for your trouble

GerhardHolzinger · January 22, 2014, 09:24

Only the cells that lie between different levels of refinement are affected, right? This is caused by the hanging nodes introduced by the mesher in order to achieve the refinement.

Check this post http://www.cfd-online.com/Forums/ope...tml#post452712

The cells fall into checkMesh's definition of a non-orthogonal cell although the cell - to the user - seems perfectly orthogonal.

November 21, 2013, 08:30	orthogonal cells marked as nonOrthogonal	#1
colinB Senior Member Join Date: Aug 2010 Location: Groningen, The Netherlands Posts: 216 Rep Power: 18	Hi Foamers, I have some troubles with cells which are marked as nonOrthogonal but are according to my interpretation perfectly orthogonal. checkMesh says maxOrth: 75.xxx with 10k cells in a mesh of 3.1M cells. I'm using LTSInterfoam in a more or less simple channel flow with a ship. The cells causing troubles are created with a refinementBox in sHM If somebody could give me an explanation to that phenomena and maybe an explanation on how I can avoid them, would be great. See attached some pictures which should illustrate the problem: NonOrthoFaces_1.jpg NonOrthoFaces_2.jpg NonOrthoFaces_3.jpg NonOrthoFaces_5.jpg NonOrthoFaces_7.jpg If you have further questions or need more information let me know regards Colin

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November 21, 2013, 08:31		#2
colinB Senior Member Join Date: Aug 2010 Location: Groningen, The Netherlands Posts: 216 Rep Power: 18	some more pics: NonOrthoFaces_8.jpg NonOrthoFaces_9.jpg thx for your trouble

January 22, 2014, 09:24		#3
GerhardHolzinger Senior Member Gerhard Holzinger Join Date: Feb 2012 Location: Austria Posts: 339 Rep Power: 28	Only the cells that lie between different levels of refinement are affected, right? This is caused by the hanging nodes introduced by the mesher in order to achieve the refinement. Check this post http://www.cfd-online.com/Forums/ope...tml#post452712 The cells fall into checkMesh's definition of a non-orthogonal cell although the cell - to the user - seems perfectly orthogonal.