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-   -   high frequency vibrating surface (http://www.cfd-online.com/Forums/fluent/89173-high-frequency-vibrating-surface.html)

ehooi June 7, 2011 04:29

high frequency vibrating surface
 
Hi all,
Has anybody tried using FLUENT to solve problems where the velocity is a sinusoidal function with very high frequency such that

u=Awsin(wt),

where w is the angular frequency. I have seen papers where problems with small w (50Hz) are solved. Has anyone seen papers or tried this for w in the range of 20000Hz?

Can FLUENT handle such high frequency problems?

Thanks a lot.

Sincerely,
EH

skullCFD June 7, 2011 10:28

I worked previously with 600 Hz. It had some convergence issues but was not that bad. I am not sure of 20 kHz! If it is not confidential, I am curious to know your problem scenario where something is vibrating at 20 kHz. My case was a synthetic jet. Thanks.

ehooi June 7, 2011 12:21

Hi,
Thank you. The actual application is more than 20kHz, for instance in Ultrasound in biological tissues where the frequency can be as high as 2MHz.

Perhaps FLUENT will not be able to do this.

Sincerely,
EH

skullCFD June 7, 2011 19:39

Thank you. I got it. May be, you can try a transient simulation using a very, very small time-step, something like < 0.5 times of (1/20MHz). But depending on your geometry/mesh size, it might take weeks/months to obtain a solution at practical times.


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