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

Simple question

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 22, 2005, 08:48
Default Simple question
  #1
Thomas
Guest
 
Posts: n/a
Hello.

Is it possible to define an expression or AV equal to Pressure.Gradient (or Velocity.Gradient) in CFX pre and use it for some calculations??

Thomas
  Reply With Quote

Old   March 23, 2005, 08:03
Default Re: Simple question
  #2
Thomas
Guest
 
Posts: n/a
To add some precision, I would like to get: d2u/dx2 (second derivative of Velocity u). With USER_GETVAR, I can get without problem du/dx, as I get from this routine Velocity u.Gradient and all the composant (du/dx, du/dy, du/dz). As these composant are only available in CFX-Post, I cannot use them to calculate d2u/dx2. I can just calculate Velocity u.Gradient.Gradient... which is not the same!

Someone can help me?? Thomas
  Reply With Quote

Old   March 24, 2005, 13:58
Default Re: Simple question
  #3
Thomas
Guest
 
Posts: n/a
Nobody able to calculate d2u/dx2??
  Reply With Quote

Old   March 28, 2005, 13:19
Default Re: Simple question
  #4
Phil
Guest
 
Posts: n/a
You cannot directly use gradients in CEL expressions; you'll have to write your own User Fortran routine to calculate the second derivative.
  Reply With Quote

Old   March 28, 2005, 13:41
Default Re: Simple question
  #5
Thomas
Guest
 
Posts: n/a
Yes but how?? Because I can get the second derivative, but not d2u/dx2...
  Reply With Quote

Old   March 29, 2005, 20:26
Default Re: Simple question
  #6
Neale
Guest
 
Posts: n/a
Thomas, as Phil says you will have to implement a second derivative calculation in user fortran to get what you want. This is not available "built in".

Neale
  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
Simple Outlet Question m.nichols19 OpenFOAM 3 June 25, 2010 01:44
Simple Question Regarding Symmetry Planes Atella CFX 3 April 11, 2010 06:44
Simple Question Regarding Symmetry Planes Atella Main CFD Forum 0 April 9, 2010 10:58
Question of Anil Date's SIMPLE method universez Main CFD Forum 0 November 18, 2009 21:12
Simple Question Regarding Continuity Closure RC FLUENT 2 March 25, 2004 06:30


All times are GMT -4. The time now is 21:24.