CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

Very large martix handling

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

LinkBack Thread Tools Display Modes
Old   November 10, 2002, 13:02
Default Very large martix handling
Vinay Kumar
Posts: n/a
In CFD problems, as we decrease grid spacing, the number of grid points increases rapidly. If we use the approach of matrix generation than we need to declare very large matrices but, in principle, there is a limit to matrix size we can handle using FORTRAN or any other programming language. Infact, practically there is no such limit and people handle such matrices. I want to know the tricks and techniques for the same.

Please help.



  Reply With Quote

Old   November 11, 2002, 12:42
Default abt matrix size
Abhijeet Vaidya
Posts: n/a
in TDMA we always break up the problem into 1 -d irrespective of whether the problem is 2-d or 3-d. We never assemble a "global matrix" which FEM people do. Thus with finite volume technique, this problem generally do not come .
  Reply With Quote

Old   November 12, 2002, 01:27
Default Re: Very large martix handling
Posts: n/a
The matrices are generally very sparse, most of the entries are zero. There are software available for handling sparse matrices in an efficient way. See the online book by Youcef Saad titled "Iterative Methods for Sparse Linear Systems". If you cant find this on the net, then let me know so that I can mail it to you.
  Reply With Quote

Old   November 12, 2002, 10:28
Default error message
Posts: n/a
I am sometimes getting this time message .What does this mean Exactly? run-time error M6101: MATH - floating-point error: invalid Domain error******** Manas
  Reply With Quote

Old   November 12, 2002, 15:29
Default Re: Very large martix handling
Posts: n/a
Sounds like a data structure question. I suggest that you read about linked lists. This is the way to handle large unstructured matrices in fortran.

If you know the structure of your matrix beforehand, then you might be able to use an easier data structure, eg: tri-diagonal, penta-diagonal, whatever... if you don't then it's back to linked lists.

  Reply With Quote

Old   December 9, 2002, 11:07
Default Re: Very large martix handling
m malik
Posts: n/a
Shouldn't be a problem if you deal with the nonzero elements only. You may look into; that may help.
  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
Postprocessing large data sets in parallel evrikon OpenFOAM Post-Processing 28 June 28, 2016 03:43
LES on a scaled geomentry (Mesh and Large scales) comb Main CFD Forum 0 February 8, 2011 07:21
large vortex on outlet when gravity accounted for Alejandra Menchaca Phoenics 0 March 3, 2009 20:53
Floworks for simulation of airflow in large rooms. kajaken FloEFD, FloWorks & FloTHERM 1 October 28, 2008 14:58
what happens if y+ is too large or too small Bo Jensen Siemens 12 February 20, 2003 00:31

All times are GMT -4. The time now is 23:23.