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

Time average value of a UDS

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 17, 2004, 08:01
Default Time average value of a UDS
  #1
ap
Guest
 
Posts: n/a
I need to calculate the time average value of a User Defined Scalar in my simulation.

Is there a macro which does this?

Hi and thanks

ap
  Reply With Quote

Old   April 17, 2004, 11:44
Default Re: Time average value of a UDS
  #2
Ajay
Guest
 
Posts: n/a
FLUENT has this option "Data sampling for Time statistics" when you do an unsteady calculation in the iterate panel that might help. I havent used it before. -Ajay
  Reply With Quote

Old   April 17, 2004, 15:10
Default Re: Time average value of a UDS
  #3
ap
Guest
 
Posts: n/a
Thank you. But that option just enable statistics for a small set of variables, and not for a UDS.

Hi

ap
  Reply With Quote

Old   April 18, 2004, 07:46
Default Re: Time average value of a UDS
  #4
thomas
Guest
 
Posts: n/a
hello, The Data sampling for Time statistics should not be very difficult to compute via UDF. Just need 2 variables: - A: one to store your UDS value at each time step. - B: a second one to store the number of time step (= to the number of UDS values store in the first variable). - your time average is A/B

That can be done using a DEFINE_EXECUTE_AT_END (with an UDMI inside) and the command C -> '=+' for each variable. Post-treating the UDMI will give you your UDS time average.

Hope this help, Thomas

  Reply With Quote

Old   April 18, 2004, 15:25
Default Re: Time average value of a UDS
  #5
ap
Guest
 
Posts: n/a
Thank you Thomas.

I thought to that method, but I have to use a really small time step (0.0001 s) to simulate a long time (1 to 2 minutes), so, if I sum all values I think I'll obtain an overflow. Any idea?

Hi

ap
  Reply With Quote

Old   April 19, 2004, 02:56
Default Re: Time average value of a UDS
  #6
thomas
Guest
 
Posts: n/a
Maybe do your averaging every 10 time step or so.
  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
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36
How to write k and epsilon before the abnormal end xiuying OpenFOAM Running, Solving & CFD 8 August 27, 2013 15:33
Upgraded from Karmic Koala 9.10 to Lucid Lynx10.04.3 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03
Velocity blows up suddenly after 30,000+ iterations lordvon OpenFOAM 14 October 27, 2010 11:13
directMapped problem panda60 OpenFOAM Bugs 4 July 8, 2010 10:23


All times are GMT -4. The time now is 03:33.