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

[ICEM] How to improve bad quality elements that are obtained after creating prism layers?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 10, 2015, 14:00
Smile How to improve bad quality elements that are obtained after creating prism layers?
  #1
New Member
 
Rohith Giridhar
Join Date: Apr 2015
Posts: 13
Rep Power: 2
Rohith Giridhar is on a distinguished road
Hi All,

I have a volume mesh with a minimum quality of 0.4289. When I create the prism layers on the blade surface using this volume mesh, the quality of the tetra elements become very poor with a minimum quality of 3.74823e-005. All these bad elements which have a quality less than 0.3 are found near the blade surface as shown in attached figure 1. I found some suggestions on the prism layer settings from this forum and from Simon's Prism/No Pyramids PPT and these were the following changes in the Prism mesh set up that I have made which reduced the number of many bad quality elements significantly. They are:

a.) Minimum prism quality=0.000001
b.) Ortho weight=0.1
c.) Fillet ratio=0.5
d.) Maximum prism angle=180.
e.) Prism height limit factor=1
f.) Smoothing options=> Number of smoothing steps:0
g.) Advanced Prism Meshing Parameters: Auto-Reduction:Check.

But, I still have some bad quality elements and I don't know how to improve their quality. Most of these bad quality elements are located near the tip of the blade as shown in attached figure 2.

How do I improve the quality of these elements? Also, what would be the acceptable quality for elements in the mesh that I must have before transferring this mesh to Fluent? And are there any other parameters that I need to check and improve before transferring this mesh to Fluent?

Could anybody please let me know regarding these? Thank you!
Rohith Giridhar is offline   Reply With Quote

Old   July 11, 2015, 02:49
Default
  #2
New Member
 
Join Date: Jan 2015
Posts: 19
Rep Power: 3
**Anny** is on a distinguished road
I also had some trouble with a blade surface... maybe you find something in my old post Bad Quality
good luck
**Anny** is offline   Reply With Quote

Old   July 11, 2015, 18:04
Default
  #3
New Member
 
Rohith Giridhar
Join Date: Apr 2015
Posts: 13
Rep Power: 2
Rohith Giridhar is on a distinguished road
Hi Anny,

Thank you for your reply. I saw your post and used those suggestions. I had already generated a Delauney mesh for my volume mesh and had reduced the curvature proximity limit. But this time I split the prism layers and redistributed based on the initial height. The number of bad elements decreased.

As, suggested in the post, I tried to smooth all the tetra elements above 0.4 by freezing other elements but was unable to do so.
I have attached a picture of the bad tetra elements that have a quality less than 0.4 which seems to be scattered around the blade.

I have also attached a picture of all the bad quality elements upto 0.3 now and I see that all of them are located along the trailing edge of the blade only.

I noticed that in your post you had mentioned that the thickenss of your trailing edge was only 1.5mm and that could be the reason for bad elements.
My trailing edge is sharp with no thickness. Could this be the reason for obtaining all these bad elements?
Could you please let me know how I could go about with this?
Thank you!
Rohith Giridhar is offline   Reply With Quote

Reply

Tags
bad quality, icem 15.0, prism layers, unstructured mesh

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
[ICEM] Negative volume error in hybrid mesh siw ANSYS Meshing & Geometry 4 September 3, 2014 05:25
how to deal with bad quality cells? phsieh2005 OpenFOAM 3 July 20, 2011 09:35
Improve Mesh quality - airfoil simulation Lukas84 STAR-CCM+ 4 July 6, 2010 10:07
"flat tetrahedral elements" Tudor Miron CFX 4 March 18, 2004 17:23
CFX4.3 -build analysis form Chie Min CFX 5 July 12, 2001 23:19


All times are GMT -4. The time now is 16:35.