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

FEM data interpolation

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 1, 2003, 21:09
Default FEM data interpolation
  #1
abhijit
Guest
 
Posts: n/a
Hi all,

I need some good interpolation techniques for interpolation of FEM data from cell center of linear triangle to the triangle nodes. I tried to search the net but these days you get more junk on the web than useful information...and i don't really have the to sort the junk information. If anybody out there knows please direct me to appropriate source.

I tried inverse-distance weighting and cell area/volume averaging but they are not satisfactory.

thanks

abhijit
  Reply With Quote

Old   August 9, 2003, 10:52
Default Re: FEM data interpolation
  #2
Jonas Holdeman
Guest
 
Posts: n/a
Since no one has replied to your request, let me give you a suggestion. It is what I would try first. Suppose your triangle-centered data were averages of unknown values at the corners of the triangles, i.e. for some triangle, (val_1 + val_2 + val_3)/3 = val_center. You have one equation like this for every triangle. This gives a set of algebraic equations to be solved for the data at the corner nodes. BUT, you have more unknowns than equations. Suplement these equations with boundary conditions to try to get a complete set of equations which can be solved in the usual way. If your best efforts do not produce a complete set of equations, then look for a method such as singular value decomposition (SVD). There are standard routines for doing this. One reference is the series "Numerical Methods in C/Fortran/C++...".

Remember though, such inverse problems are often unstable. Data has been lost in the averaging process which may not be recoverable.
  Reply With Quote

Old   August 9, 2003, 11:43
Default Re: FEM data interpolation
  #3
kei-tee
Guest
 
Posts: n/a
You should search cells which share the node. Then, volume (surface) weighted average is enough. Ie, Q_node = sum(V_cell*Q_center)/sum(V_cell)
  Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Single v.s. double precision Confused CFX 15 November 10, 2016 05:42
I developed an FEM toolkit in Java: FuturEye nkliuyueming Main CFD Forum 7 January 29, 2016 14:28
Interpolation of data on interfaces during initialization Chander CFX 7 August 16, 2011 13:15
How to update polyPatchbs localPoints liu OpenFOAM Running, Solving & CFD 6 December 30, 2005 18:27
Data Interpolation! varghese FLUENT 0 March 10, 2004 08:31


All times are GMT -4. The time now is 18:01.