CFD Online Logo CFD Online URL
Home > Forums > CFX

problem in getting second derivatives

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

LinkBack Thread Tools Display Modes
Old   July 2, 2004, 02:01
Default problem in getting second derivatives
Posts: n/a
hello, i wanted to solve an additional equation using USER FORTRAN code. in this equation I require second order derivatives of velocity. As in CFX there is no direct way to get second derivative (i e gradient of a gradient), i defined a temporary additional variable ( unspecified and hence algebraic type) to get the first derivative and then in one point of my main fortran program i am calling the gradient of the temporary variable (so that i can get the second derivative of velocity). the fortran program is compiling well. but when i link up the program with solver , it is returning an error. now i am getting doubt whether i will be able to solve second derivatives or not or is there is any care that should be taken while getting gradient of a gradient.

i will be extremely thankful if i get any solutions or suggestions for this

regards sreenivas
  Reply With Quote

Old   July 11, 2004, 19:27
Default Re: problem in getting second derivatives
Posts: n/a
Note that there is an example related to this in the documentation (calculating one AV as the gradient of another). The gradients are not actually stored, unless something tries to use them as a source term though CEL for another variable (at least this was the behavior in 5.6). Use the gradient as the source to a dummy equation, and then the gradients will be available for further calculations.

  Reply With Quote


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
Problem with interFoam; Wave/wiggle alpha1 behavior JonW OpenFOAM 3 February 23, 2013 21:41
UDF compiling problem Wouter Fluent UDF and Scheme Programming 6 June 6, 2012 04:43
Problem in implementing cht tilek CFX 3 May 8, 2011 08:39
natural convection problem for a CHT problem Se-Hee CFX 2 June 10, 2007 06:29
Adiabatic and Rotating wall (Convection problem) ParodDav CFX 5 April 29, 2007 19:13

All times are GMT -4. The time now is 08:01.