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Poroelastic waves - acoustic module - material definition

Posted Oct 16, 2012, 11:07 a.m. EDT Acoustics & Vibrations, Materials Version 4.2a, Version 4.3, Version 4.3a 5 Replies

Kevin Verdiere
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Hi,

I would like to model a poroelastic material with the acoustic module. However, can you tell me how I can link my parameters to material proporties.

My parameters are :
- porosity
- tortuosity
- air flow resistivity
- viscous length
- thermal length
- young's modulus E(1+j*damping)
- poisson's ratio
- density

If needed, the first five parameters give the bulk modulus, the bulk density and the speed of sound in the fluid phase with Johnson Champoux Alard model.


If it is possible to send me an comsol file example.

Thank's for your help !

Sincerely,

Kevin
5 Replies Last Post Mar 10, 2014, 3:35 a.m. EDT
Mads Herring Jensen COMSOL Employee

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Posted: 1 decade ago Oct 17, 2012, 3:51 a.m. EDT
Hi Kevin

This model is alreaddy in Comsol, if you select "pressure acoustics, frequency domain" and then set the fluid model to "Biot equivalent" and the "Porous matrix approximation" to Rigid. It is exactly the "Johnson Champoux Alard model". Have a look at the equation doisplay or the documentation.

Best regards
Mads
Hi Kevin This model is alreaddy in Comsol, if you select "pressure acoustics, frequency domain" and then set the fluid model to "Biot equivalent" and the "Porous matrix approximation" to Rigid. It is exactly the "Johnson Champoux Alard model". Have a look at the equation doisplay or the documentation. Best regards Mads
Abdoulkadri Chama
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Posted: 1 decade ago Mar 3, 2014, 4:06 p.m. EST
Hi Mads,

I have similar problem as Kevin and I am a new comsol user. How can I set the fluid model to "Biot equivalent" and the "Porous matrix approximation" to Rigid?

Thanks,
Hi Mads, I have similar problem as Kevin and I am a new comsol user. How can I set the fluid model to "Biot equivalent" and the "Porous matrix approximation" to Rigid? Thanks,
Mads Herring Jensen COMSOL Employee

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Posted: 1 decade ago Mar 3, 2014, 4:58 p.m. EST
Hi Abdoulkadri

In older versions of COMSOL go to the Pressure Acoustics domain node and then select the fluid model "Biot equivalent" (the default selected is Linear Elastic) and the "Porous matrix approximation" to Rigid? You need the Acoustics Module for this.

In COMSOL 4.4 the Johnson-Champaux-Allard (JCA) model has moved to the new Poroacoustics domain feature. Here you can directly select the JCA or Delany-Bazley-Miki.


Hi Mads,

I have similar problem as Kevin and I am a new comsol user. How can I set the fluid model to "Biot equivalent" and the "Porous matrix approximation" to Rigid?

Thanks,


Hi Abdoulkadri In older versions of COMSOL go to the Pressure Acoustics domain node and then select the fluid model "Biot equivalent" (the default selected is Linear Elastic) and the "Porous matrix approximation" to Rigid? You need the Acoustics Module for this. In COMSOL 4.4 the Johnson-Champaux-Allard (JCA) model has moved to the new Poroacoustics domain feature. Here you can directly select the JCA or Delany-Bazley-Miki. [QUOTE] Hi Mads, I have similar problem as Kevin and I am a new comsol user. How can I set the fluid model to "Biot equivalent" and the "Porous matrix approximation" to Rigid? Thanks, [/QUOTE]
Chenghao Cao
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Posted: 1 decade ago Mar 8, 2014, 12:26 p.m. EST
Hi Mads,
what I am doing is oscillatory test in the poroelastic media. During the process, the biot theory is applied.
(1) My question is how to apply a boundary load on the top of the poroelastic sample in frequency domain. It seems the corresponding displacement is a complex value rather than real value. But my displacement is real value.
(2) If the bounary load is a step stress, what can I do to apply a boundary load. Most of samples in 4.4 is in frequency.
If you can not understand what I mean, I'd like to upload my 'mph'
Hi Mads, what I am doing is oscillatory test in the poroelastic media. During the process, the biot theory is applied. (1) My question is how to apply a boundary load on the top of the poroelastic sample in frequency domain. It seems the corresponding displacement is a complex value rather than real value. But my displacement is real value. (2) If the bounary load is a step stress, what can I do to apply a boundary load. Most of samples in 4.4 is in frequency. If you can not understand what I mean, I'd like to upload my 'mph'
Linus Andersson COMSOL Employee

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Posted: 1 decade ago Mar 10, 2014, 3:35 a.m. EDT
Hi Chenghao!

Please send your model mph-file along with your questions to support@comsol.com. We will help you from there!

Best regards,
Linus

Hi Chenghao! Please send your model mph-file along with your questions to support@comsol.com. We will help you from there! Best regards, Linus

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