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Fluid structure interaction and damping ratio

Posted May 2, 2013, 5:10 p.m. EDT Modeling Tools & Definitions, Parameters, Variables, & Functions, Structural Mechanics Version 4.3 2 Replies

Matthias Gaucher-Petitdemange
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Hello,

My model is a vascular cantilever beam (the first mode is pictured below). I work simultaneously on COMSOL and on my experiments. The channel is to be filled with a silicone fluid which will increase the damping of the structure (confirmed by experiments).

Note that I can perfectly model the beam with an empty channel on COMSOL, the results for damping and natural frequencies are identical to the experiments (I use the frequency domain analysis while applying a force at the tip of the beam). However, I still try to make the fluid structure interaction working (ie: adding the silicone fluid in the channel):

- I tried different approaches to model the silicone in the Solid Mechanics module: bulk + shear modulus, added mass + shear force, Young's Modulus + Poisson's ratio... Without good results.

- The "Fluid structure interaction" module in COMSOL looks perfect for this model, the inputs are the viscosity and the density of the fluid, no need to estimate bulk, shear modulus, etc... But I cannot make the simulation running since 1) there is no obstacle in the fluid flow -> error message and 2) frequency study is not available in FSI.

Thanks,
Matthias
2 Replies Last Post May 3, 2013, 10:20 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 3, 2013, 12:56 a.m. EDT
Hi

I'm interested too, as for me there is currently a big hole in the "solid" capability of COMSOL it's when we interact with fluids for eigenfrequency or quasi static cases. As I do not have the acoustic module I suspect that some of the responses are there, but I'm NOT doing true "acoustics" only structural modelling interacting with fluids for damping and added mass. So far my attempts have not been very successful.

If we are many enough to complain to COMSOL, that will increase the priority for them to implement this so hopefully something will come.

Any tricks to help will be very useful I see for several of us ;)

--
Good luck
Ivar
Hi I'm interested too, as for me there is currently a big hole in the "solid" capability of COMSOL it's when we interact with fluids for eigenfrequency or quasi static cases. As I do not have the acoustic module I suspect that some of the responses are there, but I'm NOT doing true "acoustics" only structural modelling interacting with fluids for damping and added mass. So far my attempts have not been very successful. If we are many enough to complain to COMSOL, that will increase the priority for them to implement this so hopefully something will come. Any tricks to help will be very useful I see for several of us ;) -- Good luck Ivar
Matthias Gaucher-Petitdemange
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Posted: 1 decade ago May 3, 2013, 10:20 a.m. EDT
Hello Ivar,

Indeed, COMSOL support suggested me to use the Acoustics module, I will give it a try and let you know about the results.

Thanks,
Matthias
Hello Ivar, Indeed, COMSOL support suggested me to use the Acoustics module, I will give it a try and let you know about the results. Thanks, Matthias

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