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

[ICEM] Low quality mesh

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 21, 2012, 11:59
Default Low quality mesh
  #1
New Member
 
Join Date: May 2012
Posts: 1
Rep Power: 0
Memme is on a distinguished road
I have to mesh an object and some of its changes. The critical area is represented by two surfaces with an angle of 30 degrees.
After this process I have to import the mesh in fluent.

Until the creation of prism, the quality of the mesh appears very good (> 0.1-0.2).

I explain what I do step by step.

I import a acis format, built topology (all lines are red).
I create a Octree mesh, delete all the volume elements and proceed with a smoothing operation:
- 50 iterations up to 0.6 (Laplace with allow node merging activeted);
- 10 iterations up to 0.4 (no Laplace).

After I create a Delaunay mesh to fill the volume.

Before generating prism:
- 10 iterations up to 0.6 (Laplace);
- 10 iterations up to 0.6 (no Laplace);
- 10 iterations up to 0.6 (Laplace);
- 10 iterations up to 0.6 (no Laplace).


I extracted a good mesh with these prism settings, but I have to improve it:
Initial height: 0.0002 (this size is necessary).
Height ratio: 1.2.
Number of layers: 5.
Fix marching not activated.
Min prism quality: 0.01.
Ortho weight: 0.2.
Fillet ratio: 0.1.
Max prism angle: 180.
Smoothing options:
Surface smoothing steps: 0.
Volume smoothing steps: 10.
Max directional smoothing steps: 5.
First layer smoothing steps: 1.
Auto reduction activated.
Use existing quad layers.

I noticed that there are a lots of problematic tetra_4 elements that not disapperead after a smoothing.
Also often after the smoothing, the export fails.

I've try also different settings to limit the pyramids, but I didn't got good results:
Prism settings:
Exponential.
Initial height: 0.0002.
Height ratio: 1.2.
Number of layers: 5.
Fix marching not activated.
Min prism quality: 0.000001.
Ortho weight: 0.2.
Fillet ratio: 0.1.
Max prism angle: 180.
Smoothing options:
Surface smoothing steps: 0.
Volume smoothing steps: 10.
Max directional smoothing steps: 5.
First layer smoothing steps: 1.
Auto reduction activated.

Finally:
- 50 iterations up to 0.6, penta_6 freeze (no Laplace).
- 5 iteration up to 0.01 (no Laplace).

I do not know what to improve.
I used also thin cuts and edge criterion options.
Before the prism, the histogram appears clear until 0.2.
Thanks in advance and sorry for my english.
Best regards.
Memme is offline   Reply With Quote

Old   May 25, 2012, 02:02
Default
  #2
Member
 
Andrey
Join Date: Sep 2011
Posts: 86
Rep Power: 16
Ralen is on a distinguished road
Attach *.tin.
Ralen is offline   Reply With Quote

Reply

Tags
fluent, icem cfd


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[snappyHexMesh] No layers in a small gap bobburnquist OpenFOAM Meshing & Mesh Conversion 6 August 26, 2015 09:38
[ICEM] Tetra mesh quality before and after prism layer Chander ANSYS Meshing & Geometry 0 December 25, 2011 22:04
Icemcfd 11: Loss of mesh from surface mesh option? Joe CFX 2 March 26, 2007 18:10
How to control Minximum mesh space? hung FLUENT 7 April 18, 2005 09:38
Gambit Mesh quality TOM FLUENT 1 February 8, 2002 07:00


All times are GMT -4. The time now is 14:23.