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

CGNS unsteady dilemna

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 16, 2011, 10:13
Default CGNS unsteady dilemna
  #1
New Member
 
Andy Smith
Join Date: Feb 2011
Posts: 1
Rep Power: 0
smitha is on a distinguished road
Hi,

Currently I have a dilemna with using CGNS to store flow solution data for unsteady problems. Perhaps someone out there has gotten around this problem doing something simple that I've overlooked.

I'm attempting to write multiple flow solutions to a CGNS file. I'm doing this for two reasons: 1) when running my code in an unsteady mode, I use a 3 level, fully implicit technique which requires two solutions be stored in the file for clean restarts. 2) storing temporal snapshots of the flow solution for post-processing.

I have gone through the documentation in terms of writing BITER/ZITER data in order to "manage" the storage of time step values, iteration values, and flow solution pointers as the flow solution is written. The examples listed in the documentation have CGNS files opened with MODE_MODIFY.
If the files are opened with MODE_MODIFY, it is possible to overwrite BITER/ZITER data. If the files are opened with MODE_WRITE, it is not possile to overwrite the data (unless the CGNS file is built from scratch again, which is tantamount to closing and reopening).

I believe I am currently restricted to using MODE_WRITE because I'm trying to develop a system that writes partial flow solution data to a file.
If I write partial flow solution data to the file in MODE_MODIFY, part of the existing solution is deleted, and the part I'm attempting to write, writes ok. The point is, when I call a cg_field_partial_write, the part of the flow solution that I am not currently writing gets clobbered with MODE_MODIFY.

Is there a way to either

a) use MODE_WRITE, write and overwrite BITER/ZITER data, as needed duing an unsteady simulation?

or

b) use MODE_MODIFY, and write out partial field data without clobbering the flow solution.

Regards,

Andy
smitha is offline   Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[CGNS] CGNS converters available mbeaudoin OpenFOAM Meshing & Mesh Conversion 137 December 14, 2018 05:20
Error with the unsteady flamelet Model Christoph_84 FLUENT 0 February 25, 2010 12:06
conditions for unsteady problems dvdromnu OpenFOAM Running, Solving & CFD 5 November 9, 2009 03:15
Unsteady simulation on the flow around Naca0012 Peter Pan Zhang FLUENT 2 June 11, 2006 20:53
steady or unsteady? (in dpm) winnie FLUENT 1 April 28, 2003 12:30


All times are GMT -4. The time now is 21:46.