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

Forces in Symmetry

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 18, 2009, 07:52
Default Forces in Symmetry
  #1
Matt
Guest
 
Posts: n/a
Hi,

I'm wanting to calculate the resultant force on a body. The body is axi-symmetric in 2 planes; hence, at a zero angle of attack, two of the component forces should equal zero. Therefore, one force on the body can be found; that is in the direction of the fluid.

When I do the computation for the whole body (not using a symmetry plane), two of the component forces are zero and the one that's left (in the direction of flow) gives me the force on the body... which is what I want.

So, here's the problem: When using a symmetry plane, to reduce computation time, the forces do not seem to appreciate the symmetry I have set. Flow visualisation is fine with the symmetry; just force calculation does not match up. I get a huge force in the direction normal to the symmetry plane. I think it is calculating a force on the body in this direction, and not appreciating that an equal and opposite force should be on the other side of the symmetry plane.

I may not have a setting enabled or perhaps symmetry planes are not built for this... Any help would be much appreciated.

Thanks in advance,

Matt
  Reply With Quote

Old   February 18, 2009, 17:40
Default Re: Forces in Symmetry
  #2
Glenn Horrocks
Guest
 
Posts: n/a
Hi,

The force in the simulation with the symmetry planes is the force acting on the simulated section. It does not take into account symmetry. This means you are likely to get large larges which in the true geometry are cancelled out. So you can ignore force components perpendicular to a symmetry plane for the total force on the body.

Glenn Horrocks
  Reply With Quote

Old   February 25, 2009, 06:41
Default Re: Forces in Symmetry
  #3
Matt
Guest
 
Posts: n/a
Hi Glenn,

Thanks for your help. Much appreciated.

Matt
  Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[ICEM] Blocking and Symmetry BrolY ANSYS Meshing & Geometry 32 August 24, 2012 04:13
FORCES don't run! C12Carbon OpenFOAM 0 September 10, 2011 08:34
Forces and Plane of Symmetry Riaan FLUENT 3 February 8, 2005 06:02
Forces with symmetry plane Rob FLUENT 1 July 16, 2002 05:55
Valve Forces in CFdesign Mike Clapp Main CFD Forum 3 March 8, 2001 15:09


All times are GMT -4. The time now is 07:37.