CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > ANSYS Meshing & Geometry

[ICEM] Refine All Mesh problem with hexahedral grids

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree1Likes
  • 1 Post By FSVH

Reply
 
LinkBack Thread Tools Display Modes
Old   August 11, 2014, 15:46
Default Refine All Mesh problem with hexahedral grids
  #1
New Member
 
Fernando S. V. Hurtado
Join Date: Aug 2014
Posts: 2
Rep Power: 0
FSVH is on a distinguished road
Hi,

My objective is to perform a convergence analysis of a numerical method in a series of progressively refined unstructured grids. In order to do this, consistent refinement is important, that is, all grids should maintain the same structure. I found that the ICEM option Edit Mesh => Adjust Mesh Density => Refine All Mesh was the right tool for doing that.

Things were fine with tetrahedral grids. I used a coarse base-grid and applied successively the Refine All Mesh tool for obtaining increasingly refined grids. I obtained excellent results in that way.

The problem arose when I tried to do the same with hexahedral grids. After refining once and exporting the refined grid, I realized that the parts representing boundaries werenít saved by ICEM. I checked the grid with the diagnostic tool in ICEM and it said that there were a lot of uncovered faces. ICEM tried to fix the problem covering the exposed faces and putting the new faces into a new part. Apparently, all faces on all boundaries were put in the new part. The weird thing is that those faces werenít uncovered at all, because there were boundary parts with quadrilateral elements coincident with the faces of the adjacent hexahedra.

I did several tests with different geometries and different base-grids and I observed that the problem appears whenever boundaries have quadrilateral elements, even when they are mixed with triangles. I donít know if Iím doing something wrong or it is an implementation issue in ICEM, related only to the refinement of hexahedral or quadrilateral elements.

Any help would be greatly appreciated. By the way, Iím using ICEM 15.0.
FSVH is offline   Reply With Quote

Old   August 13, 2014, 16:36
Thumbs up
  #2
New Member
 
Fernando S. V. Hurtado
Join Date: Aug 2014
Posts: 2
Rep Power: 0
FSVH is on a distinguished road
After close examination, I found the source of the problem. The Refine All Mesh tool creates more nodes than would be necessary when the elements are hexahedral. Some nodes on the boundary parts are actually repeated. When that happens, the connectivity of an adjacent hexahedron is defined with one node, whereas the connectivity of an adjacent boundary quadrilateral is defined with other node located at the same position. I have no idea why this happens, but after merging the coincident nodes, the diagnostic tool didn't find any further problem with the grid.
H.R.D. likes this.
FSVH is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
3D Hybrid Mesh Errors DarrenC ANSYS Meshing & Geometry 11 August 5, 2013 06:42
Icemcfd 11: Loss of mesh from surface mesh option? Joe CFX 2 March 26, 2007 18:10
Convergence problem when refine the mesh... TB CFX 16 June 17, 2005 04:33
Gambit problems Althea FLUENT 21 February 6, 2001 08:05
unstructured vs. structured grids Frank Muldoon Main CFD Forum 1 January 5, 1999 11:09


All times are GMT -4. The time now is 01:24.