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

Smooth reconstruction of flowsolution

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 13, 2008, 14:00
Default Smooth reconstruction of flowsolution
  #1
Carlos
Guest
 
Posts: n/a
Can anyone give me any references about smooth reconstruction of different order of accuracy of numerical flow solutions for postprocessing? I need to compute the result of applying the differential Euler or Navier-Stokes operators to a continuous flowfield obtained by smooth reconstruction of a numerical solution obtained with a node-centered 3D finite-volume code. Any clues? Thanks!
  Reply With Quote

Old   February 13, 2008, 15:01
Default Re: Smooth reconstruction of flowsolution
  #2
rt
Guest
 
Posts: n/a
there are variaty of methods for this purpose,

your field is formally C0 space, because in formal numerical method we just attend to continuty of field not its derivative (it is very obvious in FEM)

a very general method (not computationally cheap) is to assume a desired smooth space (C^n, n>=1) with its basis (e.g. high order spline basis) and then solve a least square problem to find unknown interpolation coefficient, this system is not essentially wel-posed (and could be over/under specify) and maybe methods like SVD are needed.

if you search computer graphics literature you find several alternatives, your problem is common there.

if you look for a toolbox have a look at this: http://www.farfieldtechnology.com/

as a very simple and easy to implement solution:

assume your filed is member of L2 space (space filled by square integrable function, Hilbert space, L2-norm = \int (.)^2 ), so there is not garantee to have continuous derivative.

then you want to have a filedwith continuty of first derivative, so we should map from L2 to H1 (H1 is Sobolev space filled with function has continuous first derivative, H1-norm = \int (.)^ + \nabla(.)^2)

assume g is original and G is smoothed filed, for this mapping you should solve this poisson equation (weak solution):

- \nabla \cdot (\nabla G) + G = g

to control lenght scale of smoothing, it could be modified to:

- \nabla \cdot (D \nabla G) + G = g

where D is diffusion coefficent control smoothing, D = 0, could give original field.

Hope this helps.

  Reply With Quote

Old   February 14, 2008, 13:25
Default Re: Smooth reconstruction of flowsolution
  #3
Carlos
Guest
 
Posts: n/a
Thanks rt! I'll take a look at your suggestions.
  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
Implicit Residual Smooth of Jameson Scheme hhuang84 Main CFD Forum 0 November 7, 2010 10:44
[Commercial meshers] ST_Malloc: out of memory.malloc_storage: unable to malloc Velocity SA, cfdproject OpenFOAM Meshing & Mesh Conversion 0 April 14, 2009 16:45
ICEM 10 smooth transition error Stephen CFX 3 March 13, 2007 10:23
Smooth plots of external data samu Siemens 2 May 21, 2006 14:08
Help for implicit residual smooth!! D.T. Main CFD Forum 0 May 6, 2003 13:49


All times are GMT -4. The time now is 03:14.