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4.2a Acoustic Streaming

Posted 2024/06/25 9:33 GMT-4 Acoustics & Vibrations, Computational Fluid Dynamics (CFD), Microfluidics 3 Replies

Peter Hartwig
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Hello,

I am trying to create a simulation of the acoustic streaming in COMSOL v4.2a. As this is quite an old version, I cannot find much information on the subject.

I understand that first-order fields should be solved with a pressure acoustics or thermoacoustics interface, and then these fields should be implemented as source terms(?) in a laminar flow interface.

Actually carrying out this process seems complex.

Is anyone able to advise me on where I can find more detailed instructions on modelling the acoustic streaming in v4.2a, or would anyone have any model files that they would be willing to share with me.

With best regards, Peter

3 Replies Last Post 2024/07/05 9:20 GMT-4
Edgar J. Kaiser Certified Consultant
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Posted: 10 months ago 2024/06/25 9:44 GMT-4

Peter,

just for your information, the current version 6.2 has it readily available with a time explicit solver. I have been doing some extensive work with it, with good success. I would not want to go through the exercise to cook it by myself in an old version.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Peter, just for your information, the current version 6.2 has it readily available with a time explicit solver. I have been doing some extensive work with it, with good success. I would not want to go through the exercise to cook it by myself in an old version. Cheers Edgar
Peter Hartwig
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Posted: 10 months ago 2024/06/25 9:50 GMT-4

Peter,

just for your information, the current version 6.2 has it readily available with a time explicit solver. I have been doing some extensive work with it, with good success. I would not want to go through the exercise to cook it by myself in an old version.

Cheers Edgar

Dear Edgar,

Thank you for your reply. I have seen the available multiphysics for acoustic streaming but unfortunately I do not have access to the latest version. I have been attempting to recreate results from literature on the subject that used the 4.2 version but their explanations of the details are vague.

I understand this is not ideal but it is currently my only option.

Best regards, Peter

>Peter, > >just for your information, the current version 6.2 has it readily available with a time explicit solver. I have been doing some extensive work with it, with good success. I would not want to go through the exercise to cook it by myself in an old version. > >Cheers >Edgar Dear Edgar, Thank you for your reply. I have seen the available multiphysics for acoustic streaming but unfortunately I do not have access to the latest version. I have been attempting to recreate results from literature on the subject that used the 4.2 version but their explanations of the details are vague. I understand this is not ideal but it is currently my only option. Best regards, Peter
Peter Hartwig
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Posted: 10 months ago 2024/07/05 9:20 GMT-4
Updated: 10 months ago 2024/07/09 7:29 GMT-4

Just as a follow up, I tried to follow this paper which seems to state that I need to add a body force and a weak contribution to the creeping flow interface in terms of the first-order field variables solved for in the acoustics physics interface.

I don't have any experience with equation-based modelling but if anyone could assist me in how I can add these contributions to the fluid flow interface it would be a great help.

The authors say they added a weak contribution which I think is implemented as which corresponds to the RHS of this equation. But I am not sure how to implement the RHS of this equation as a volume force.

Just as a follow up, I tried to follow [this paper](https://pubs.rsc.org/en/content/articlelanding/2012/lc/c2lc40612h) which seems to state that I need to add a body force and a weak contribution to the creeping flow interface in terms of the first-order field variables solved for in the acoustics physics interface. I don't have any experience with equation-based modelling but if anyone could assist me in how I can add these contributions to the fluid flow interface it would be a great help. The authors say they added a [weak contribution](https://ibb.co/pvg8NRX) which I think is implemented as \begin{verbatim} -0.5*(d(real(ta.rho*conj(u)),x)+d(real(ta.rho*conj(v)),y))*test(p2) \end{verbatim} which corresponds to the RHS of [this equation](https://ibb.co/G737PTf). But I am not sure how to implement the RHS of [this equation](https://ibb.co/Gn0qtWc) as a volume force.

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