# spanwise wavenumber calculation

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 November 12, 2012, 04:37 spanwise wavenumber calculation #1 New Member   Muhammad Nadeem Join Date: May 2009 Posts: 5 Rep Power: 8 Hi All! I am trying to compute spanwise wavenumber,kz for premultilpied spectra of streamwise veloity. I have spanwise length of Lz = 80 and node points, Nz = 256. How can I calculate spanwise wavenumber,kz ? Any help will be appriciated.

November 12, 2012, 07:32
#2
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Filippo Maria Denaro
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Quote:
 Originally Posted by Nadeem99 Hi All! I am trying to compute spanwise wavenumber,kz for premultilpied spectra of streamwise veloity. I have spanwise length of Lz = 80 and node points, Nz = 256. How can I calculate spanwise wavenumber,kz ? Any help will be appriciated.
Are you talking about the maximum wavenumber? in general the frequency is linked to the wavenumbers:

fz = kz * Lz/2*pi

and the Nyquist frequency will be fx_max= Lz/(2*h) so than

1/(2*h)= kz_max /2*pi

kz_max = pi/h

November 12, 2012, 20:06
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Quote:
 Originally Posted by FMDenaro Are you talking about the maximum wavenumber? in general the frequency is linked to the wavenumbers: fz = kz * Lz/2*pi and the Nyquist frequency will be fx_max= Lz/(2*h) so than 1/(2*h)= kz_max /2*pi kz_max = pi/h

Thank you for your response. I want to calculate all wave numbers from minimum to maximum.

I want to conform one thing. Does 'h' refers to span-wise spacing?

Once again thanks for your response.

November 13, 2012, 05:00
#4
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Filippo Maria Denaro
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Quote:
 Originally Posted by Nadeem99 Thank you for your response. I want to calculate all wave numbers from minimum to maximum. I want to conform one thing. Does 'h' refers to span-wise spacing? Once again thanks for your response.

yes, h stands for dz in your case

 November 13, 2012, 22:21 #5 New Member   Muhammad Nadeem Join Date: May 2009 Posts: 5 Rep Power: 8 Thanks a lot for your help.

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