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Turbulent Channel 1D Energy Spectra Calculation

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Old   October 23, 2015, 17:13
Default Turbulent Channel 1D Energy Spectra Calculation
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stran1028
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Hello,

I have 2 point correlation data for a turbulent channel case and I'm trying to put together a script to compute the 1D energy spectra from this. To verify my script, I'm using both 2 point correlations from DNS runs done by Moser et al (http://turbulence.ices.utexas.edu/data/MKM/chan395/) and trying to recreate their 1D energy spectra.

Based on what I've seen in literature, the 1D energy spectra should just be the FFT of the 2 point correlation function. However when I try to do this in matlab using the fft function, I'm not able to match Moser's spectra.

A snippet of my matlab code which calculates this is shown below. This was based on the examples shown for the fft function on the matlab website.

yhat=fft(Ruu);
tmpEuu= abs(yhat/L);
Euu = tmpEuu(1:L/2 + 1);
Euu(2:end-1) = Euu(2:end-1);

Any help would be greatly appreciated! Thank you!
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Old   October 24, 2015, 03:38
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Quote:
Originally Posted by stran1028 View Post
Hello,

I have 2 point correlation data for a turbulent channel case and I'm trying to put together a script to compute the 1D energy spectra from this. To verify my script, I'm using both 2 point correlations from DNS runs done by Moser et al (http://turbulence.ices.utexas.edu/data/MKM/chan395/) and trying to recreate their 1D energy spectra.

Based on what I've seen in literature, the 1D energy spectra should just be the FFT of the 2 point correlation function. However when I try to do this in matlab using the fft function, I'm not able to match Moser's spectra.

A snippet of my matlab code which calculates this is shown below. This was based on the examples shown for the fft function on the matlab website.

yhat=fft(Ruu);
tmpEuu= abs(yhat/L);
Euu = tmpEuu(1:L/2 + 1);
Euu(2:end-1) = Euu(2:end-1);

Any help would be greatly appreciated! Thank you!

you should search for similar post wherein this issue was already discussed
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correlations, energy spectrum, fft, matlab, turbulent channel flow

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