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February 13, 2020, 10:40 |
Pressure spectra - FFT for pressure field
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#1 |
Senior Member
Jiri
Join Date: Mar 2014
Posts: 209
Rep Power: 13 |
Hello,
this is a question I asked in CFX forum but I would like to verify the capability of Fluent: when doing a transient analysis in Fluent, can Fluent make FFT (or DFT) of pressure for each node on a surface in order that I could obtain pressure contour in the frequency domain? |
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February 13, 2020, 11:10 |
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#2 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,654
Rep Power: 65 |
Fluent does have FFT support but it can only be performed on a monitor. This means it is limited to points, a bunch of points, or surface integrals. You can get the pressure spectrum in frequency domain, but you can't do a multi-dimensional surface DFT and get spatial modes.
Also, doing this in Fluent, while convenient, also means the plot itself is stuck in Fluent. It's cumbersome to do follow-up post-processing. So keep that in mind. |
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February 13, 2020, 11:33 |
Spectrum vs point-value
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#3 |
Senior Member
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Whatever tool you use, you will have to decide which parameter and which value do you want to plot as contour. When FFT is done on, say pressure at a point, output is a profile and not a single value. To plot a contour, a value needs to be selected from the profile.
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Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. |
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February 14, 2020, 03:57 |
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#4 |
Senior Member
Jiri
Join Date: Mar 2014
Posts: 209
Rep Power: 13 |
Thank you both for the recommendation. What are your suggestion then? I guess to export transient data points to an external FFT and then visualize the contour for selected frequency in Matlab? Or could you suggest any other tool for the visualization if you have any experience with this?
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February 14, 2020, 06:22 |
Tool
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#5 |
Senior Member
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Yes, matlab or octave or tecplot or Fluent. Its a matter of convenience, I suppose. If you wish to plot contours on the domain itself, you can combine all the FFT profiles into a single one, bring those to Fluent, and then plot as contours on the the boundary. It's good to have a context. However, any other tool should show similar behavior if spatial coordinates are used to plot 3D contours.
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Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. |
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