[linyanx]

Hello all,

I was trying to investigate the frequency characheristic of my original system. Thus, the Bode diagram was my first choice. However, the option are not explicitly found in the STARCCM. I think this is doable because the Bode diagram can be plotted in Fluent, another widely used CFD software.

Could you please indicate how to plot the Bode diagram, for the observation of frequency characteristic of system, in STARCCM? Any advice would be greatly appreciated.

Best regards,
Linyan

[steve lee]

Hi,
You mean this?
https://en.wikipedia.org/wiki/Bode_plot

Use expression report or field function with X-Y plot

[linyanx]

Hello Lee,

Yes, that's exactly what i'm trying to do, the Bode plot. Thank you very much!

Cheers,
Linyan

Originally Posted by steve lee

Hi,
You mean this?
https://en.wikipedia.org/wiki/Bode_plot

Use expression report or field function with X-Y plot

[linyanx]

Plus, for the expression or field function, do you mean I have to define/create an expression on my own? I was trying to find the related tutorials with respect to field function of Bode plot. Nothing can be found yet.

Originally Posted by steve lee

Hi,
You mean this?
https://en.wikipedia.org/wiki/Bode_plot

Use expression report or field function with X-Y plot

[steve lee]

Yes, you should make a expression or field function yourself..
I agree there are very lack of information in help about expression and fieldfunction.
But they improved field function. Try to define!

[me3840]

You can create fourier transforms of recorded data and display them in monitor plots as a function of frequency. I would suggest you look at aeroacoustic tutorials and look through tools>data set functions

[linyanx]

Hello guys,
It's been a while since last response. Thanks for steve and me3840's answer.

I would like to detail the way to plot the Bode diagram with STAR-CCM, believe this could help others who have the similar question.

To plot the Bode diagram in STAR, due to the inaccessibility of the system matrice, the Bode diagram cannot be created directly. Instead, it can be plot based on the principle of the frequency response of the system, i.e., the frequency response of system's transfer function = FFT(output signal)/FFT(input signal). Therefore, in order to plot the Bode diagram:

1. a sin/cos input with a sample frequency f1 is applied to the system;
2. the response signal from the system is recorded;
3. apply fast fourier transfer to input signal and output signal from step 1,2 respectively;
4. calculating the Bode magnitude plot at frequency f1 with: 20log_10{FFT(output, f1)/FFT(input, f1)}; calculating the Bode phase plot at frequency f1 with [phase(output(f1))-phase(input(f1))];
5. iterate step 1-4 at different frequency f2, f3... on your own intesest

[linyanx]

hello me3840 and steve,

thanks for your help on my question, I put my fellow-up explaination above. Please correct me if necessary.

Best regards,
linyanx

[Kummi]

Hello Linyan,


Hope you are doing good. Have you created Bode plot using matrices or any feedback loop system ? Can you elaborate it please.


Thank you