high frequency vibrating surface

ehooi · June 7, 2011, 05:29

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, 11:28

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, 13:21

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, 20:39

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.

June 7, 2011, 05:29	high frequency vibrating surface	#1
ehooi Member EH Join Date: Dec 2010 Posts: 61 Rep Power: 15	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

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June 7, 2011, 11:28		#2
skullCFD Member Join Date: Apr 2011 Posts: 30 Rep Power: 15	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.

June 7, 2011, 13:21		#3
ehooi Member EH Join Date: Dec 2010 Posts: 61 Rep Power: 15	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

June 7, 2011, 20:39		#4
skullCFD Member Join Date: Apr 2011 Posts: 30 Rep Power: 15	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.