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-   -   Pao spectrum. Steps? (http://www.cfd-online.com/Forums/main/6040-pao-spectrum-steps.html)

GG April 27, 2003 07:27

Pao spectrum. Steps?
 
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?


Tom April 27, 2003 09:14

Re: Pao spectrum. Steps?
 
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

GG April 29, 2003 04:20

But that report is not available
 
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?

Tom April 29, 2003 06:52

Re: But that report is not available
 
Hi,

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

Tom

GG April 29, 2003 11:29

They are about 13 steps (depending how you count)
 
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?



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