Flow resistivity
Posted 04.06.2024, 12:34 GMT-4 Structural & Acoustics, Acoustics & Vibrations, Studies & Solvers Version 5.6 4 Replies
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Hello everyone, I have a technical question. I have a rectangular geometry and inside it I have several small spheres to simulate a false porous medium. My study is acoustic (Acoustic pressure in the frequency domain). Is there a way to account for the flow resistivity in this medium using formulas in COMSOL?
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For modeling the acoustics of porous materials, there are a few different approaches:
Use a Poroacoustic Material model in Pressure acoustics. This is a fluid-equivalent homogenized model, so the geometry will only be the macro scale and not include any microstructure. The material model gets assigned to the entire domain. The flow resistivity is a common input to some Poroacoustic material models. https://doc.comsol.com/6.2/docserver/#!/com.comsol.help.aco/aco_ug_pressure.05.005.html
Use Poroelastic Waves interfaces to model the porous material based on Biot Theory
Use Thermoviscous Acoustics to model the detailed viscous and thermal losses that occur in boundary layers surrounding the fluid-microstructure interface. In this case, the geometry includes the detailed microstructure. This is usually only feasible for a unit cell due to the scale.
The first approach is the easiest and most lightweight approach.
-Mark
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Thanks Mark, my case is that I need to obtain (for scientific purposes) the acoustic parameters of the porous medium such as absorption, reflection, transmission loss, tortuosity and flow resistivity (Sigma). I studied the first three and managed to plot them in COMSOL, now the flow resistivity and tortuosity, although they are formulas, I cannot implement them analytically in COMSOL (in the variables tab!).
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There should no issue in implementing a formula under variables. Which error message do you get? Also, have a look at the JCA models under Poroacoustics. You can enter user defined expressions here as desired.
-------------------René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
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You need to learn 1) AFR testing standard 2) CFD module will be needed to find the AFR
-------------------iamrajakumar@iitkgp.ac.in
iamrajakr@gmail.com
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