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Old   March 8, 2012, 17:52
Default Energy spectrum to physical domain
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HJ
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i am wondering can i get real velocity from energy spectrum function (frequency domain), which can have a form like sinusoid function?
Can i set temporal difference equal to zero in the autocorrection function?
In this way i think i can only get the mean value of u_i square. or is there any other way?
Thanks
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Old   March 9, 2012, 04:58
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Filippo Maria Denaro
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Quote:
Originally Posted by wanghaojie View Post
i am wondering can i get real velocity from energy spectrum function (frequency domain), which can have a form like sinusoid function?
Can i set temporal difference equal to zero in the autocorrection function?
In this way i think i can only get the mean value of u_i square. or is there any other way?
Thanks
is your spectrum derived from a temporal signal? In general, you can construct a velocity field in space with a prescribed spectrum, however you need to prescribe other condition in order to construct all the Fourier coefficients
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Old   March 10, 2012, 11:42
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is your spectrum derived from a temporal signal? In general, you can construct a velocity field in space with a prescribed spectrum, however you need to prescribe other condition in order to construct all the Fourier coefficients
Thanks. I havent start the experiment yet. I think i will get temporal signal instead of spatial. And can you please tell me what other conditions do I need?
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Old   March 11, 2012, 16:14
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Originally Posted by wanghaojie View Post
Thanks. I havent start the experiment yet. I think i will get temporal signal instead of spatial. And can you please tell me what other conditions do I need?
since your velocity field is v(x,t) = Sum_p,q,r Cpqr(t) exp (i k .x ) you need to know the real and imaginary part of your Fourier coefficients
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