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

Unsteady flow initializing?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 2, 2005, 07:23
Default Unsteady flow initializing?
  #1
Erica
Guest
 
Posts: n/a
Hi,all When I initialize an unsteady flow, there is erro info @Error: FLUENT received fatal signal (ACCESS_VIOLATION) 1. Note exact events leading to error. 2. Save case/data under new name. 3. Exit program and restart to continue. 4. Report error to your distributor. Error Object: ()@

What this mean? Anyone can give some help? What are the possible reason for this erro? I can't patch the flow domain.

Thanks for any help

Erica

  Reply With Quote

Old   March 2, 2005, 20:16
Default Re: Unsteady flow initializing?
  #2
Peter
Guest
 
Posts: n/a
That error is common when trying to access data that Fluent usually doesn't keep. You can get Fluent to keep the data in memory by typing solve/set/expert and answering yes to the question about temporary memory. Sometimes it is necessary to enter this command and then run a single steady state iteration before setting the problem up in the desired transient form. Hopefully this works for you.
  Reply With Quote

Old   March 3, 2005, 00:43
Default Re: Unsteady flow initializing?
  #3
Erica
Guest
 
Posts: n/a
Thank you very much, I'll try next.
  Reply With Quote

Old   March 3, 2005, 18:49
Default Re: Unsteady flow initializing?
  #4
Erica
Guest
 
Posts: n/a
Hi,Peter. Thanks for your help. There is another question. I'm doing a case in which I define a mass source depent on the wall temperature. when I intialize the flow field, that error occurs. I wonder whether there are any other reason for it or not? The UDF source compiled successfully, but can't intialize? Is it possible there are some mistakes in the UDF code?

Thanks any help.

Erica
  Reply With Quote

Old   March 4, 2005, 01:00
Default Re: Unsteady flow initializing?
  #5
Melaku H.
Guest
 
Posts: n/a
Hi,

There are many work arounds to avoid that error. Fluent doesn't keep the data that it doesn't need. If you need the data..e.g. previous temperature at the wall or something...then one way to get it it by using a User Defined Memory. There is a way of telling the Fluent "black box" code to creat a memory location and save whatever data you need later for your UDF.

I don't know your particular case but in general Fluent doesn't have anything at the begining of the transient iteration except for the inital data...so you have to insert a little "if command.." like

if CURRENT_TIME = 0.0 or some time you have.. then return else .. run the UDF..

this lets u skip the initial time step. This is what I can say so far...but there might be someother work around. Keep on tying. its experiment afterall only on PC tho.

Melaku H.

rgds
  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
how to predict unsteady flow from case definition? Felix Main CFD Forum 6 August 28, 2007 16:40
Unsteady flow in FLUENT Vidya Raja FLUENT 2 November 2, 2005 16:29
Unsteady Boundary Layer Flow Wen Long Main CFD Forum 0 July 29, 2002 23:08
fluid flow fundas ram Main CFD Forum 5 June 17, 2000 21:31
computation about flow around a yawed cone Tylor Xie Main CFD Forum 0 June 9, 1999 07:33


All times are GMT -4. The time now is 20:44.