[GAMBIT] tangent edges and high skewness

CaroVandame · May 3, 2012, 23:21

Hello everyone

I'm trying to mesh a bagless filter which looks like the one on the picture with hexahedral cells only.
At first my inlet was one volume and my "center piece" was another one. However, it creates a very small sliver at the connection, and meshing it leads to high skewness cells.

Here are my questions:
-is there an easy way to select a particular cell and refine it in one direction in Gambit?
-is this one case where using virtual geometries could help? I could create virtual faces that include both my sliver face and my central face, and mesh it easily, however, at the connections planes, how do I match the meshes?

Any idea/tip/... will be greatly appreciated, I'm quite new to Gambit!

Thanks
Caroline

CaroVandame · May 3, 2012, 23:25

Or third question: can Fluent directly adapt cells under a certain quality threshold? And can you adapt only in one direction?

Far · May 4, 2012, 01:34

http://www.youtube.com/watch?v=KabKFrJK3fM

http://www.youtube.com/watch?v=hkHoXMCpfMk

-mAx- · May 4, 2012, 02:28

can you post a picture with a zoom at your skewed cells

CaroVandame · May 4, 2012, 10:41

Very interesting video, thanks, but like mAx, I wonder what your skewness is at the tangent point?

It is easy to create the same kind of mesh in Gambit, but the cells at the tangent junction are highly skewed...

CaroVandame · May 4, 2012, 16:45

What about tmerge?
The good point is I can define the cylinder slice at the level of the inlet and the inlet as one volume, and I can mesh it easily (the sliver disappears inside the bottom face). However, part of this "merged" bottom face needs to be defined as interior and the other one as wall. I don't know how to do that. Creating virtual faces doesn't help since they don't get exported.
Any input?

CaroVandame · May 4, 2012, 20:37

UPDATE: it seems that tmerge is the way to go (or use Fluent's ability to open multiple meshes at once).
Now I have problems with Fluent to create the grid interfaces, so I'll open a new thread in the right forum!

Thanks everyone

Far · May 7, 2012, 03:11

For grid interfaces (in gambit), you should search the older posts by -mAx-, where he has explained very nicely that how to decouple two volumes and create the interfaces.

AND/OR

If you can send geometry privately or attach on forum, then I can make the mesh for your in ICEM CFD.

CaroVandame · May 7, 2012, 10:39

Thanks Far, but I think I figured it out!
Like you said, mAx posts were quite useful.

Here is the new thread if someone is interested.
http://www.cfd-online.com/Forums/flu...tml#post359498

May 3, 2012, 23:21	tangent edges and high skewness	#1
CaroVandame New Member Caroline Vandame Join Date: Aug 2010 Posts: 26 Rep Power: 16	Hello everyone I'm trying to mesh a bagless filter which looks like the one on the picture with hexahedral cells only. At first my inlet was one volume and my "center piece" was another one. However, it creates a very small sliver at the connection, and meshing it leads to high skewness cells. Here are my questions: -is there an easy way to select a particular cell and refine it in one direction in Gambit? -is this one case where using virtual geometries could help? I could create virtual faces that include both my sliver face and my central face, and mesh it easily, however, at the connections planes, how do I match the meshes? Any idea/tip/... will be greatly appreciated, I'm quite new to Gambit! Thanks Caroline

May 4, 2012, 01:34	Similar, but done in ICEM	#3
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	http://www.youtube.com/watch?v=KabKFrJK3fM http://www.youtube.com/watch?v=hkHoXMCpfMk

May 4, 2012, 02:28		#4
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	can you post a picture with a zoom at your skewed cells __________________ In memory of my friend Hervé: CFD engineer & freerider

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
limit high velocity values	riesotto	OpenFOAM	7	July 25, 2016 15:28
Importing CAD geometry and Editing edges to match	Ahmed	CFX	15	March 21, 2016 13:39
Gambit mesh: tangent edges and high skewness	CaroVandame	FLUENT	2	May 3, 2012 23:21
Boundary layer meshing with sharp trailing edges	Andrew Berner	FLUENT	1	August 28, 2007 18:39
high aspect ratio elements	Olivier	CFX	5	April 3, 2003 07:55

May 3, 2012, 23:25		#2
CaroVandame New Member Caroline Vandame Join Date: Aug 2010 Posts: 26 Rep Power: 16	Or third question: can Fluent directly adapt cells under a certain quality threshold? And can you adapt only in one direction?

May 4, 2012, 10:41		#5
CaroVandame New Member Caroline Vandame Join Date: Aug 2010 Posts: 26 Rep Power: 16	Very interesting video, thanks, but like mAx, I wonder what your skewness is at the tangent point? It is easy to create the same kind of mesh in Gambit, but the cells at the tangent junction are highly skewed...

May 4, 2012, 16:45		#6
CaroVandame New Member Caroline Vandame Join Date: Aug 2010 Posts: 26 Rep Power: 16	What about tmerge? The good point is I can define the cylinder slice at the level of the inlet and the inlet as one volume, and I can mesh it easily (the sliver disappears inside the bottom face). However, part of this "merged" bottom face needs to be defined as interior and the other one as wall. I don't know how to do that. Creating virtual faces doesn't help since they don't get exported. Any input?

May 4, 2012, 20:37		#7
CaroVandame New Member Caroline Vandame Join Date: Aug 2010 Posts: 26 Rep Power: 16	UPDATE: it seems that tmerge is the way to go (or use Fluent's ability to open multiple meshes at once). Now I have problems with Fluent to create the grid interfaces, so I'll open a new thread in the right forum! Thanks everyone

May 7, 2012, 03:11		#8
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	For grid interfaces (in gambit), you should search the older posts by -mAx-, where he has explained very nicely that how to decouple two volumes and create the interfaces. AND/OR If you can send geometry privately or attach on forum, then I can make the mesh for your in ICEM CFD.

May 7, 2012, 10:39		#9
CaroVandame New Member Caroline Vandame Join Date: Aug 2010 Posts: 26 Rep Power: 16	Thanks Far, but I think I figured it out! Like you said, mAx posts were quite useful. Here is the new thread if someone is interested. http://www.cfd-online.com/Forums/flu...tml#post359498