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Acoustic streaming due to bubble oscillations

Posted 2025/06/10 17:23 GMT-4 Acoustics & Vibrations, Computational Fluid Dynamics (CFD), Microfluidics Version 6.2 2 Replies

Subrahmanyam Cherukumilli
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Hi,

I'm trying to simulate the acoustic streaming due to the bubble oscillations in a cylindrical cavity under acoustic fields from literature. I'm unable to get the expected streaming. It would be of great help if someone could help me figure out what is wrong in my setup. I expected the flow away from the bubble as in the reference but mine is reverse.

Thanks,

2 Replies Last Post 2025/06/11 12:39 GMT-4
Jonas Helboe Jørgensen COMSOL Employee

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Posted: 6 months ago 2025/06/11 3:26 GMT-4

Dear Subrahmanyam Cherukumilli,

I think the solution is to change from Pressure Acoustics to Thermoviscous Acoustics for the modeling of the acoustic field, see attached model. The reason is that the acoustic streaming in this model seams to be driven from the corners of the geometry. These effects are not accounted for when using Pressure Acoustics. When using Pressure Acoustics the effects of the viscous boundary layer is accounted for analytically and one of the assumptions is that the geometry features is larger than the viscous and thermal boundary layers. Instead when using Thermoviscous Acoustics the acoustic velocity field is modeled directly.

Also note that the perturbation method used for model acoustic streaming does not include nonlinear effects, which can be important for large bubble oscillations.

Best regards, Jonas

Dear Subrahmanyam Cherukumilli, I think the solution is to change from Pressure Acoustics to Thermoviscous Acoustics for the modeling of the acoustic field, see attached model. The reason is that the acoustic streaming in this model seams to be driven from the corners of the geometry. These effects are not accounted for when using Pressure Acoustics. When using Pressure Acoustics the effects of the viscous boundary layer is accounted for analytically and one of the assumptions is that the geometry features is larger than the viscous and thermal boundary layers. Instead when using Thermoviscous Acoustics the acoustic velocity field is modeled directly. Also note that the perturbation method used for model acoustic streaming does not include nonlinear effects, which can be important for large bubble oscillations. Best regards, Jonas
Subrahmanyam Cherukumilli
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Posted: 6 months ago 2025/06/11 12:39 GMT-4

Dear Jonas,

Thanks for your reply. Unfortunately, I'm unable to see the attached file since I'm using COMSOL 6.2. Doesn't the Thermoviscous Boundary Layer Impedance account for streaming in Pressure acoustics. To ensure the boundary layers are smaller I used a fine mesh features for the boundary layers. I couldn't find a reference of Thermoviscous Acoustics that i could use for my case. It would be of great help if there is a way to view the 6.3 V file in my 6.2 version. Please let me know if my current setup is correct.

Is transient interface is the ideal scenario for my setup instead of frequency domain to account for the bubble oscillations ?

Best regards, Subrahmanyam

Dear Jonas, Thanks for your reply. Unfortunately, I'm unable to see the attached file since I'm using COMSOL 6.2. Doesn't the Thermoviscous Boundary Layer Impedance account for streaming in Pressure acoustics. To ensure the boundary layers are smaller I used a fine mesh features for the boundary layers. I couldn't find a reference of Thermoviscous Acoustics that i could use for my case. It would be of great help if there is a way to view the 6.3 V file in my 6.2 version. Please let me know if my current setup is correct. Is transient interface is the ideal scenario for my setup instead of frequency domain to account for the bubble oscillations ? Best regards, Subrahmanyam

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