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

About the POD

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 19, 2003, 12:29
Default About the POD
  #1
wudor
Guest
 
Posts: n/a
It is said that one can reduce the time and cost of computation by use of reduced-order models. While when we reconstruct the flow field, the initial data from the numerical simulation or experiments are still needed. It seems that it doesn't reduce the data storage. Thanks.
  Reply With Quote

Old   February 19, 2003, 17:32
Default Re: About the POD
  #2
Peter Attar
Guest
 
Posts: n/a
I'm not quite sure what you mean by data storage. While it is true that to construct a POD reduced order model simulation data from the original full model must be computed at least once, from then on the reduced system is much smaller and computation can be made much faster..
  Reply With Quote

Old   February 20, 2003, 12:14
Default Re: About the POD
  #3
wudor
Guest
 
Posts: n/a
I am sorry I don't know much about the POD, but what kind of computation can be made much faster?
  Reply With Quote

Old   February 20, 2003, 12:23
Default Re: About the POD
  #4
Peter Attar
Guest
 
Posts: n/a
The speed of computation is more or less based on the number of DOF to be solved for. POD reduces this number...therefore the computation is sped up. It has been applied to aerodynamic and aeroelastic computations which used vortex lattice,Euler and Navier Stokes fluid equations. Look for the authors Dowell,Hall and Thomas for references.
  Reply With Quote

Old   February 20, 2003, 12:54
Default Re: About the POD
  #5
Question Man.
Guest
 
Posts: n/a
Ignoreance is bliss!!, but what is POD? Can someone explain it?
  Reply With Quote

Old   February 20, 2003, 13:23
Default Re: About the POD
  #6
Tim
Guest
 
Posts: n/a
check out:

G Berkooz, P Holmes, and JL Lumley. "The Proper Orthogonal Decomposition in the Analysis of Turbulent Flows", Annu. Rev. Fluid Mech. 1993 , Vol. 25: 539-575.
  Reply With Quote

Old   February 20, 2003, 13:25
Default Re: About the POD
  #7
Peter Attar
Guest
 
Posts: n/a
Proper Orthogonal Decomposition. Essentially it is a coordinate transformation which maps the flow variables(for example pressure,velocity,density) from a large dimension subspace to a smaller dimension subspace via the coordinate transform. It is of the same thought as what is done with structural dynamics where the structural deformation can be thought of as a linear combination of some global modes...for the fluid simulation the pressure etc can be described by a reduced set of bases. The bases("modes") are found by solving the eigenvalue problem [C]{v}=lamda{v} where C is the correlation matrix formed by putting snapshots of the original full model data into a matrix(call it Q) a forming the correlation C=Q*Q^T. The POD modes are then formed via [U]=[Q][V] See the reference I gave above for more(better) detail.

  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
Pod nikwin OpenFOAM 3 April 9, 2010 07:12
POD or ROM (Proper Orthogonal Decomposition) mike Main CFD Forum 8 June 10, 2006 03:39
Snapshot Proper Orthogonal Decomposition (POD) Mehmet SEN Main CFD Forum 7 May 19, 2006 12:38
What is the difference between POD and SVD? Greene Main CFD Forum 1 February 15, 2006 18:32
Looking for free POD program for Euler equations TooT Main CFD Forum 0 August 15, 2003 21:31


All times are GMT -4. The time now is 19:34.