Hi all,
I have done a CFD for a cylinder and obtained a transient pressure data at a point using DES. I have put time step size 1e-04 seconds. I got a frequency (ater FFT of the data) of 540 Hz. Now when I performed the same in experiment with 5000 Hz sample frequency, I obtained various frequencies at 100, 200, 500 and 900 Hz. while the 500 Hz is nearer to my CFD it should be the largest mode since analytically also the same frequency is obtained using a/2L formula. Please help !
I think that for the cylinder wake several harmonics are amplified, depending on the Reynolds number, so that your result should depend on the position of the point where you're collecting your data, in particular the distance from the cylinder on the streamwise direction.
I assume the signal should have been filtered. Alongside, kindly check if there is any beating phenomenon observed which may be introducing additional modes.
Shamoon Jamshed : You will have to identify the cause of the beating. Is it inherited in the system or if it occurs due to noise. If it is happening due to noise, then you can filter the signal using various band filters. If you are using MATLAB for your signal processing, this should help you.
https://in.mathworks.com/help/signal/ref/bandpass.html
Regards,
Rameez
- Badges
- Science topic