Pressure spectra - FFT for pressure field

Jiricbeng · January 30, 2020, 09:13

Hi there,

when doing transient analysis in CFX, can CFD Post make FFT (or DFT) of pressure for each node on a surface in order that I could obtain pressure contour in frequency domain? How to figure this out in CFX / CFD Post ?

ghorrocks · January 30, 2020, 16:36

I would export the data and do the FFT in an external package like matlab or python.

Jiricbeng · January 31, 2020, 02:46

Thank you for the answer, Glenn. Ok, but can such data (any external data basically) be visualized in CFD Post? I guess only via import-> import surface, line or point data?

If so, it is just "point" data. But how to proceed to get a surface contour? Well I managed to do that by "User surface". But you must include "face connectivity" otherwise you obtain just point data.

But is there any similar way to import spatial data? Spatial data of my variable which could be visualized for example by cross-section plane? The surface data was figured out by "User surface", but an analogous way is not possible for spatial distribution of a user defined variable.

ghorrocks · January 31, 2020, 05:39

You can't get other data into CFD-Post easily. You would have to export the position data as well so you could plot this externally.

Jiricbeng · February 3, 2020, 03:01

And is there any "uneasy" way to do that?

ghorrocks · February 3, 2020, 04:36

You can get data into CFD-Post via the data import function in solver manager. I am not sure I got the name exactly right as I am not at work at the moment. You could write the data in a format it accepts (such as CGNS) and then you can get it into CFD-Post. But this is very "uneasy"

January 30, 2020, 09:13	Pressure spectra - FFT for pressure field	#1
Jiricbeng Senior Member Jiri Join Date: Mar 2014 Posts: 221 Rep Power: 13	Hi there, when doing transient analysis in CFX, can CFD Post make FFT (or DFT) of pressure for each node on a surface in order that I could obtain pressure contour in frequency domain? How to figure this out in CFX / CFD Post ?

January 30, 2020, 16:36		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144	I would export the data and do the FFT in an external package like matlab or python. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

January 31, 2020, 02:46		#3
Jiricbeng Senior Member Jiri Join Date: Mar 2014 Posts: 221 Rep Power: 13	Thank you for the answer, Glenn. Ok, but can such data (any external data basically) be visualized in CFD Post? I guess only via import-> import surface, line or point data? If so, it is just "point" data. But how to proceed to get a surface contour? Well I managed to do that by "User surface". But you must include "face connectivity" otherwise you obtain just point data. But is there any similar way to import spatial data? Spatial data of my variable which could be visualized for example by cross-section plane? The surface data was figured out by "User surface", but an analogous way is not possible for spatial distribution of a user defined variable. Last edited by Jiricbeng; January 31, 2020 at 05:44.

January 31, 2020, 05:39		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144	You can't get other data into CFD-Post easily. You would have to export the position data as well so you could plot this externally. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 3, 2020, 04:36		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144	You can get data into CFD-Post via the data import function in solver manager. I am not sure I got the name exactly right as I am not at work at the moment. You could write the data in a format it accepts (such as CGNS) and then you can get it into CFD-Post. But this is very "uneasy" __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

February 3, 2020, 03:01		#5
Jiricbeng Senior Member Jiri Join Date: Mar 2014 Posts: 221 Rep Power: 13	And is there any "uneasy" way to do that?

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