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

ICEM stopping the prism mesh

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 26, 2007, 13:58
Default ICEM stopping the prism mesh
  #1
Wooster
Guest
 
Posts: n/a
I have a problem with ICEM stopping the prism mesh early and failing to finish adding the layers required. The mesh isn't particularly large (refined) compared to some others (that work). Everything seems to be working, but once it reaches the 8th layer (out of 10) it just stops the prism application. I can't find any error messages that tell me what is going on. Anyone have any ideas what is causing this?

-W
  Reply With Quote

Old   August 26, 2007, 15:53
Default Re: ICEM stopping the prism mesh
  #2
Wooster
Guest
 
Posts: n/a
One of the most frustrating things is finding the obvious after hours of checking. For anyone experiencing this, examine the sizing of your prism mesh. Sometimes a 0.001 will look like a 0.0001.

  Reply With Quote

Old   August 28, 2007, 06:50
Default Re: ICEM stopping the prism mesh
  #3
Pankaj
Guest
 
Posts: n/a
I was facing this problem for prisms.

But Whenever I did it before any smoothing operation on tet,it worked.

And prisms always downs the quality of mesh hence I switched to prism warpage of 0.01. Never gone beyond this.

If u got any solution,convey it.

Thanks and regards, Pankaj.
  Reply With Quote

Old   August 29, 2007, 07:17
Default Re: ICEM stopping the prism mesh
  #4
Wooster
Guest
 
Posts: n/a
I'll try that, but I found in my particular case that the prism height began to overrun itself and the geometry. So for instance a prism height of 0.001 was actually larger (when the layers came out) than my geometry. I changed the tetra scheme and inflation ratio (to test different ideas) and found that it had a lot to do with the sizing. Sometimes I could get another layer in before it stopped. That's when I noticed that my 0.001 should be a 0.0001 (a typo on my part). I'm not sure why it didn't warn me that the mesh would not fit in the geometry. Right now that's my chief suspect and if the mesh is built with geometry in mind, this shouldn't happen (as I found out by a mere typing mistake).

-W
  Reply With Quote

Old   August 30, 2007, 05:32
Default Re: ICEM stopping the prism mesh
  #5
Dr. FLow Squad
Guest
 
Posts: n/a
I often use a different approach when creating prisms in my existing volume mesh. First I only create one layer of prisms setting the "Initial Height" to the size of my "Global Element Scale Factor" or higher and the "Prism Height Limit Factor" to 0.95 (Important!). After running the prisms mesher I smooth everything but "Penta_6" which are "freezed". Finally I split the prisms to 5 to 20 Number of layers using a prism ratio of 1.2. That gives you a good prism mesh... -Dr. Flow squad
  Reply With Quote

Old   August 30, 2007, 15:56
Default Re: ICEM stopping the prism mesh
  #6
Wooster
Guest
 
Posts: n/a
I never thought about making my layers like that. Makes sense. I'll try that on a couple of my models that have nasty mesh issues. Thanks

-W
  Reply With Quote

Old   September 4, 2007, 12:28
Default Re: ICEM stopping the prism mesh
  #7
Wooster
Guest
 
Posts: n/a
I tried this on some of my simpler meshes and I did get very good results. However, the thickness of the prism mesh is key to good answers and I've been playing around with this setup to identify an easy way of controlling the thickness. Basically, I need an initial height of 0.00075(") and I'm wondering how the setting would work since in your example you set it to the global Element Factor. I'm not 100% sure about if I should change the prism height limitation factor (0.95 as prescribed). Any thoughts on this?

-W
  Reply With Quote

Old   September 5, 2007, 05:16
Default Re: ICEM stopping the prism mesh
  #8
Dr. FLow Squad
Guest
 
Posts: n/a
No. I rarely set the initial height, since I often work with small cylinders (ducts) that opens up into very large cylinders. Therefore I have different cell size depending on the diameter of the cylinder. Thats why the Prism height limitation factor works well for me. Maybe you could elaborate with an image?
  Reply With Quote

Old   September 5, 2007, 12:24
Default Re: ICEM stopping the prism mesh
  #9
Wooster
Guest
 
Posts: n/a
Not sure I can send an image yet (patent stuff, etc.). I asked the question earlier for another issue but the gods haven't answered yet. Basically I have the same idea where I have a tube that's about 0.055" going into a huge annulus (2"). A mesh study revealed that the thickness of the prism layer can really determine results, hence I have to be careful about how thick the prism layers can be. I'm still tinkering with the setup and hopefully I can get a measure on it. Thanks a bunch!

-W
  Reply With Quote

Reply


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
Gambit problems Althea FLUENT 22 January 4, 2017 04:19
Prism mesh Mohankumarg12 ANSYS Meshing & Geometry 7 July 27, 2011 17:10
ICEM CFD Prism Mesh Generation Problem with Ansys 12.0 & windows 7 OS kh_thakor ANSYS Meshing & Geometry 1 February 1, 2011 21:22
ICEM 10 mesh question DAK565656 CFX 6 May 8, 2007 13:16
How to control Minximum mesh space? hung FLUENT 7 April 18, 2005 10:38


All times are GMT -4. The time now is 19:00.