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

CFX and ICEM CFD - structured meshes

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 3, 2009, 17:59
Default CFX and ICEM CFD - structured meshes
  #1
New Member
 
Join Date: May 2009
Posts: 21
Rep Power: 8
realanony87 is on a distinguished road
I have made a structured mesh in ICEM CFD, and the usual way I transfer it to CFX is to first convert the mesh to the unstructured format (*.uns) and open it in CFX.
Is there a way to make CFX use of the fact that the grid is a multiblock structured grid, so as to have a faster processing time ?
realanony87 is offline   Reply With Quote

Old   May 3, 2009, 18:41
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,822
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Hi,

No. CFX is a fully unstructured solver so structured meshes are treated the same as unstructured meshes. However, there are still advantages in using structured meshes in CFX - in some cases the mesh quality of a structured mesh is better and that leads to better accuracy and convergence (this is especially important for things like boundary layers, free surface and surface tension modelling); and secondly a hex mesh uses less memory than a tet mesh of equivalent resolution.

Glenn Horrocks
ghorrocks is offline   Reply With Quote

Old   May 9, 2009, 08:32
Default Puzzled
  #3
New Member
 
Stein
Join Date: Apr 2009
Location: Shanghai in China
Posts: 11
Rep Power: 8
Stein is on a distinguished road
Send a message via MSN to Stein
Quote:
Originally Posted by ghorrocks View Post
Hi,

No. CFX is a fully unstructured solver so structured meshes are treated the same as unstructured meshes. However, there are still advantages in using structured meshes in CFX - in some cases the mesh quality of a structured mesh is better and that leads to better accuracy and convergence (this is especially important for things like boundary layers, free surface and surface tension modelling); and secondly a hex mesh uses less memory than a tet mesh of equivalent resolution.

Glenn Horrocks
I feel puzzled by ur answer.
Firstly,you said CFX is a fully unstructured solver,does that mean CFX cant treat structured mesh?
Secondly ,but u still said there are still advantages in using structured meshes in CFX .
So ,it seems like your answer is in conflict.
Stein is offline   Reply With Quote

Old   May 10, 2009, 21:53
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,822
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Hi,

I mean CFX internally handles structured and unstructured meshes the same. For instance a node in a structured mesh can be referred to by its IJK coordinates. CFX does not use this and uses the unstructured approach of an element connectivity matrix which works for both structured and unstructured meshes.

My second point is that if your geometry is simple enough such that a high quality structured mesh works in your geometry then you will get better mesh quality with this type of mesh rather than an unstructured mesh.

Glenn Horrocks
ghorrocks is offline   Reply With Quote

Old   May 12, 2009, 06:22
Default
  #5
New Member
 
Stein
Join Date: Apr 2009
Location: Shanghai in China
Posts: 11
Rep Power: 8
Stein is on a distinguished road
Send a message via MSN to Stein
Well,I get it now!
There is another question.
In ICEM,how can structured mesh be constructed?
As we know,meshing by blocking approach in ICEM finally should be converted to unstructed, and then output to CFX.Howerver, other meshing approaches such as Octree tetra in ICEM are used to construct unstruceted mesh.So ,does that means ICEM cant construct structed mesh?
Secondly ,by blocking approach there is another method to convert "premesh",namely "multi-block".I dont know what this method used for.When i convert premesh to multiblock and output to CFX,error was presented all the time.Does that means CFX cant treat muti-block mesh.
Stein is offline   Reply With Quote

Old   May 12, 2009, 18:45
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,822
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Hi,

To generate structured meshes in ICEM you need ICEM-hexa. This is an additional license option, contact your CFX vendor. When you have the license and done some tutorials in hexa things will be clearer.

CFX can handle a multi-block mesh.
ghorrocks is offline   Reply With Quote

Old   May 14, 2009, 11:18
Default
  #7
New Member
 
Stein
Join Date: Apr 2009
Location: Shanghai in China
Posts: 11
Rep Power: 8
Stein is on a distinguished road
Send a message via MSN to Stein
My comprehesion is that ICEM-HEXA is just the blocking mehod in ICEM,isn't it?
By blocking ,hexa grid can be generated,but usually the premesh needs to be converted to unstructured,which I think is unstructured mesh generated at last.
Stein is offline   Reply With Quote

Old   May 14, 2009, 18:22
Default
  #8
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,822
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Hi,

No, ICEM can generate fully structured meshes. So for block structured solvers ICEM can generate meshes. It is just that when you read a structured mesh into CFX it will get treated the same as an unstructured mesh.

Glenn Horrocks
ghorrocks is offline   Reply With Quote

Old   May 14, 2009, 21:05
Default
  #9
New Member
 
Stein
Join Date: Apr 2009
Location: Shanghai in China
Posts: 11
Rep Power: 8
Stein is on a distinguished road
Send a message via MSN to Stein
Hi
About ur answer,is there any documentation or some threads containing the detailed information on how CFX treat its mesh,namely some theory about this.
Unfortunately, I cant find any specification about this in CFX's help documentation
By the way,thank u for ur help very much
Stein is offline   Reply With Quote

Old   May 14, 2009, 21:10
Default
  #10
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,822
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Hi,

It is all in the theory manual. There are also a few threads on it on this forum, use a search to find them.

Glenn Horrocks
ghorrocks is offline   Reply With Quote

Old   May 15, 2009, 05:17
Default
  #11
New Member
 
henry wang
Join Date: May 2009
Posts: 13
Rep Power: 8
suihenry is on a distinguished road
Quote:
Originally Posted by realanony87 View Post
I have made a structured mesh in ICEM CFD, and the usual way I transfer it to CFX is to first convert the mesh to the unstructured format (*.uns) and open it in CFX.
Is there a way to make CFX use of the fact that the grid is a multiblock structured grid, so as to have a faster processing time ?
Hi,
Usually, in ICEMCFD, there are output option which can save the structured mesh as .msh file. This file can be easily and directly opened in CFX.
What you need to do is to set a product option. in ICEMCFD, click the "settings" option in main menu, then choose the "Product" option, then choose the " ANSYS ICEM CFD-ANSYS Solvers Version" option. then click OK, then exist the software. When you open the ICEM CFD 11.0 again, you can click the "output" in the toolbox menu, there are four option which can save mesh as different types corresponding ANSYS software(like CFX, ANSYS, ANSYSWORKBENCH, Fluent and so on).
suihenry 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
Import Mesh from ICEM CFD to CFX Andre Almeida CFX 10 April 20, 2014 15:33
ICEM CFD to CFX geometry and mesh Luca CFX 6 February 4, 2010 17:31
Icem Cfd To Cfx B.C. Problem Kordou CFX 4 July 17, 2008 12:49
import from CFX 5.7 To ICEM CFD Salman CFX 7 October 13, 2004 13:21
importing mesh from ICEM CFD into CFX 5 Jay CFX 2 November 12, 2002 14:46


All times are GMT -4. The time now is 07:46.