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

energy source UDF

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 1, 2006, 02:46
Default energy source UDF
  #1
Jason
Guest
 
Posts: n/a
Hi,

I have a trouble about UDF. The energy produced by the chip is varied with time. Anyone can help me modify the UDF? Thanks~~

/* Heat Generation Rate UDF */

#include "udf.h"

DEFINE_SOURCE(source, cell, thread) {

real T = CURRENT_TIME ; real source ; real s1, s2, s3, s4 ; s1=10E+5 ; s2=5*10E+5 ; s3=2*10E+6 ;

if (T <= 0.05)

source = s1;

else if (0.05< T <= 0.15)

source = s2;

else if (0.15 < T)

source = s3;

return source; }
  Reply With Quote

Old   August 1, 2006, 04:43
Default Re: energy source UDF
  #2
Anon
Guest
 
Posts: n/a
A source term also needs its derivative. that is missing in all the conditions. Derivative term here is zero since your source is a constant. Units are: W/m3. Please check an example UDF in the manual.
  Reply With Quote

Old   August 2, 2006, 02:35
Default Re: energy source UDF
  #3
Jason
Guest
 
Posts: n/a
Hi Anon,

I changed my UDF as following but the result is incorrect. Could you tell me where is the error? Thanks!

* Heat Generation Rate UDF */

#include "udf.h" DEFINE_SOURCE(heat_source, cell, thread, dS, eqn)

{

real T = CURRENT_TIME ; real source ; real s1, s2, s3, s4 ; s1=5*10E+7 ; s2=10E+5 ; s3=2*10E+7 ;

if (T <= 1.5)

source = s1;

else if (1.5 < T <= 2)

source = s2;

else if (2 < T)

source = s3;

return source; }

  Reply With Quote

Old   August 2, 2006, 14:30
Default Re: energy source UDF
  #4
summer
Guest
 
Posts: n/a
You need add the derivative as ds[eqn]=0 since it seems that s1 et.al are constant. Hope it helps.
  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
Mass and energy source - evaporation neilduffy1024 ANSYS 4 July 16, 2013 23:50
Writing UDF energy source file JoFFe FLUENT 0 October 4, 2010 16:48
Momentum source UDF Matthew Brannock FLUENT 5 May 3, 2001 21:18
UDFs for Scalar Eqn - Fluid/Solid HT Greg Perkins FLUENT 0 October 13, 2000 23:03
UDFs for Scalar Eqn - Fluid/Solid HT Greg Perkins FLUENT 0 October 11, 2000 03:43


All times are GMT -4. The time now is 09:10.