# Energy spectrum in frequency

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 July 5, 2019, 07:59 Energy spectrum in frequency #1 Member   Ashish bhigah Join Date: Jan 2019 Posts: 31 Rep Power: 7 Hi I am trying to calculate the Energy spectrum, which is a concept usually applied to the wavenumber, but I want to calculate an energy spectrum in frequency. In order to do that I calculated the autocorrelation function of 3 component of velocity in one point. I did the psd of the 3 component using the autocorrelation function not normalised. Then I summed them and I divided these by two. So It is respected the fact that the mean value of turbulent kinetic energy is equal to the integral of the energy spectrum over the frequency. do you think that this approach can be acceptable in order to calculate the energy spectrum in frequency?

July 5, 2019, 08:27
#2
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Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,793
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Quote:
 Originally Posted by bhigahAshish Hi I am trying to calculate the Energy spectrum, which is a concept usually applied to the wavenumber, but I want to calculate an energy spectrum in frequency. In order to do that I calculated the autocorrelation function of 3 component of velocity in one point. I did the psd of the 3 component using the autocorrelation function not normalised. Then I summed them and I divided these by two. So It is respected the fact that the mean value of turbulent kinetic energy is equal to the integral of the energy spectrum over the frequency. do you think that this approach can be acceptable in order to calculate the energy spectrum in frequency?

frequency and wavenumber is almost the same since k=n*2*pi/L

 July 5, 2019, 08:33 #3 Member   Ashish bhigah Join Date: Jan 2019 Posts: 31 Rep Power: 7 Yes, it is what I was thinking. So this approach can be acceptable?

July 7, 2019, 07:58
#4
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Emma
Join Date: Jun 2019
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Quote:
 Originally Posted by FMDenaro frequency and wavenumber is almost the same since k=n*2*pi/L

Thanks I was using this computation but I'm hesitant same reason for the OP if it's acceptable.

July 7, 2019, 10:54
#5
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Ashish bhigah
Join Date: Jan 2019
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Quote:
 Originally Posted by ngerma Thanks I was using this computation but I'm hesitant same reason for the OP if it's acceptable.
Hi, which reasons make you hesitant?

 Tags energy spectrum, frequency