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Power dissipation in Thermoacoustics module

Posted 30 janv. 2015, 12:03 UTC−5 Heat Transfer, Structural Mechanics 1 Reply

Duy Pham
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Hello Comsol users,

I’m using COMSOL Thermoacoustics module and want to investigate the power dissipation inside a Helmholtz resonator. Therefor COMSOL has 2 options; the first one is “viscous power dissipation density” and the second one is “thermal power dissipation density”. I calculate the volume integral over the power density and compare both types of dissipation. The model and results you can find in the attachment.

Basically the results show that the thermal power dissipation is higher than the viscous power dissipation for frequencies lower than 10kHz. This is very surprising because I would expect that the viscous power dissipation has the dominant share. Also it is mentioned in many literatures that damping effects is mainly due to viscous friction. I never heard something about thermal dissipation in this context before.

So my question now is, how does COMSOL calculate the thermal dissipation? Can the thermal dissipation be explained physically? Why the thermal dissipation is so high for low frequencies? Or did I have an error in reasoning somewhere? Has someone a clue?

Any help would be appreciated. Many Thanks.

Best Regards
Duy Pham

1 Reply Last Post 24 juil. 2016, 07:09 UTC−4
COMSOL Moderator

Hello Duy Pham

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If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Bettine Gommer
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Posted: 8 years ago 24 juil. 2016, 07:09 UTC−4
Hi Duy Pham,

I am currently experiencing the same issue/question. Also regarding power dissipation in helmholtz resonators. Since it's been a while that you posted this, have you got an answer/solution for this?

Thanks!

Bettine
Hi Duy Pham, I am currently experiencing the same issue/question. Also regarding power dissipation in helmholtz resonators. Since it's been a while that you posted this, have you got an answer/solution for this? Thanks! Bettine

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