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

Pao spectrum. Steps?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 27, 2003, 07:27
Default Pao spectrum. Steps?
  #1
GG
Guest
 
Posts: n/a
Hi

I need to create the fluctuations for a LES calculation, but I don't know the detailed steps for the Pao spectrum. In every publication they say, either they used or only few equations are given, but not the detailed steps. Pao's own paper never gives those steps, only some explanation of the method. Unfortunatey, many codes have that already inside, and researchers are using that without much thinking. In my case, I'm using/developing a code without such implementation inside.

I have figured out some steps but it must be some publications where the algorithm is given. WHERE?? Where to find such algorithm?

  Reply With Quote

Old   April 27, 2003, 09:14
Default Re: Pao spectrum. Steps?
  #2
Tom
Guest
 
Posts: n/a
Hi,

Some of the steps you can find in Rogallo's report (1981, NASA TM 81315). To get an initial, isotropic turbulent field you create random fluctuations in spectral space, make sure that the divergence of the velocity field is zero, and scale the fluctuations so that you get the required energy spectrum.

Tom
  Reply With Quote

Old   April 29, 2003, 04:20
Default But that report is not available
  #3
GG
Guest
 
Posts: n/a
Hi

But not in any book?, Pao's spectrum is not even is P. Sagaut's 2nd Ed. book. I've tired to get that report from 1981 but is not available, as I expected. It must be in someone lecture notes or review paper that I'm missing, WHERE? WHERE the Pao's spectrum all steps are available?
  Reply With Quote

Old   April 29, 2003, 06:52
Default Re: But that report is not available
  #4
Tom
Guest
 
Posts: n/a
Hi,

I have just want to know the form of the Pao spectrum you can have a look at: Pope (2000) Turbulent flows.

Tom
  Reply With Quote

Old   April 29, 2003, 11:29
Default They are about 13 steps (depending how you count)
  #5
GG
Guest
 
Posts: n/a
Hi

The creation of fluctuations using Pao spectrum is not explained in Pope, chap 6.. just the equation is given there. The fluctuations are created using about 13 steps, I just want to see/confirm them. OK?

  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
spectrum: LES of a turbulent channel flow finally goes to turbulent liu OpenFOAM Running, Solving & CFD 6 November 1, 2011 02:00
A variable expressing time steps in UDF? lcw FLUENT 4 January 16, 2006 13:19
Method to determine spectrum of turbulence? Walid Main CFD Forum 2 December 2, 2005 09:29
cfx does not give time steps in cfxpost.why.urgent prakash CFX 2 November 24, 2005 00:06
LES correlation and turbulent energy spectrum Fabian Main CFD Forum 4 October 18, 2005 02:04


All times are GMT -4. The time now is 02:01.