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Old   June 14, 2008, 01:53
Default LES cut off wave number
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Fab
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Hi,

does anyone know, how to calculate the cut-off wave number of the energy spectrum when using an implicit mesh filter?

Thanks! Fab

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Old   June 14, 2008, 06:47
Default Re: LES cut off wave number
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cfd.novice
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I think its same as your grid size. But I am not sure, I hope some one with more experience can confirm this. How are doing your energy spectrum? Can you please explain the process.
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Old   June 15, 2008, 13:42
Default Re: LES cut off wave number
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Fab
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Hi,

it is probably an easy answer, when one has a cartesian aequidistant mesh, as the cut off would be 2*pi/deltaX !? With deltaX the cell size, but what can be used to for unstructured meshes!?

For a temporal energy spectrum I would do 'just' an fft of a the velocity tracked at a certain point. For the spatial spectrum I just can think of a correlation!?

Fab

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Old   June 16, 2008, 15:42
Default Re: LES cut off wave number
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cfd.novice
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Which software did you use for it? Do you mind if I have a look at the code you wrote for it. I am interested in temporal spectrum. Thank you in advance

cfd.novice
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Old   July 2, 2008, 19:39
Default Re: LES cut off wave number
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krish
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can you explain me how did you track the velocity? what was ur initial condition?

I did FFT on the velocity data that i have been given but it is not showing the energy spectrum that i see in the technical journal papers.

I think the data i got is wrong.

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