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

How to correct negative volume

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 9, 2007, 13:34
Default How to correct negative volume
  #1
aero
Guest
 
Posts: n/a
Hi, I am doing Hexahedral Meshing (using block method).

but i am getting negative volume near one of the surface.

please help me how to correct it.

Thanks & regards aero
  Reply With Quote

Old   January 9, 2007, 16:54
Default Re: How to correct negative volume
  #2
Joe
Guest
 
Posts: n/a
Convert to unstruc mesh then run the quality checker it will offer to automatically fix the problem.
  Reply With Quote

Old   January 11, 2007, 23:31
Default Re: How to correct negative volume
  #3
Luke
Guest
 
Posts: n/a
You have to check your blocking and the distribution of nodes along the edges near the negative volume elements.

  Reply With Quote

Old   January 16, 2007, 06:19
Default Re: How to correct negative volume
  #4
aero
Guest
 
Posts: n/a
Hi,

Thanks for responses given. I have worked on improving quality of Tetra Mesh but this is my first problem in which i have to improve the Hexa Mesh Quality.

can you give some details on how to improve the Hex-Mesh Quality after converting into unstructured Mesh.

Thanks & Regards aero
  Reply With Quote

Old   January 16, 2007, 06:24
Default Re: How to correct negative volume
  #5
Luke
Guest
 
Posts: n/a
The important quality parameter to check for Hex-Mesh is Determinant 3X3X3. It should be >= 0.4 To improve the quality of a hex-mesh you should first check the jump of element size between adjacent edges. The jump should not be more than 1 to 1.5 times. The second thing to check is parallel edges should have the same distribution of elements and nodes. Sometimes you might have to join/split edges to get that. After plotting the determinant histogram you can see which are the cells falling below the value 0.4 and accordingly improve on those regions. Hope this helps.

  Reply With Quote

Old   January 19, 2007, 09:53
Default Re: How to correct negative volume
  #6
aero
Guest
 
Posts: n/a
Hi,

Thanks for response. It was very usefull.

In my model i want to increase Determinant 3X3X3 to a value of 0.7 but the problem is i am geting angle value less.

Please tell me what to do?

Thanks & regards aero
  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
Turbogrid and Negative volume Ali CFX 12 August 18, 2016 14:31
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
fluent add additional zones for the mesh file SSL FLUENT 2 January 26, 2008 11:55
Dynamic Mesh, negative volume! ROOZBEH FLUENT 2 June 22, 2006 20:51
Help: Negative Volume MANOJKUMAR FLUENT 8 December 24, 2005 04:59


All times are GMT -4. The time now is 01:10.