Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
cantilever frequency response in a fluid
Posted 2010年6月23日 GMT-4 11:19 Version 3.5a 6 Replies
Please login with a confirmed email address before reporting spam
I need to simulate a cantilever which vibrates in a fluid (for instance water) and observe his frequency response.
To do that, I used 4 modules : 2 MEMS Plane Strain modules (1 for frequency response, 1 for fluid effect on the cantilever), 1 Mobile Mesh ALE module and the last is Incompressible Navier Stokes.
Except the MEMS Module for frequency response, all of the modules are transient analysis study.
Until now, when I plot the amplitude of the displacement, I get only the one which correspond to a cantilever in vaccum.
So I think there is a problem whit Navier Stokes module and parameters.
Anyone has an idea how to do this simulation ?
I used the version 3.5a of Comsol Multiphysic. I work with a 2D model
Thank you.
Teddy Maillot
Please login with a confirmed email address before reporting spam
give a look to the pdf file: FSI Analysis of Microcantilevers Vibrating in Fluid Environment.
You find it in the "Paper & Presentations" section.
All models are in 3D but I think it is quite easy to convert them in 2d. No ale module is employed and all analyses are of "Damped Eigenfrequency" type.
I hope this helps.
Alessandro
Please login with a confirmed email address before reporting spam
Thanks for this. I will take a look at it.
Teddy.
Please login with a confirmed email address before reporting spam
I read the article but when I try to run the simulation, I get the error : singular matrix (with a 2D and a 3D model).
I didn't really understand how to replace the time derivatives by "*jomega_smsld" (page 5, paragraph 3) for the Navier Stokes module.
Thank you
Teddy.
Please login with a confirmed email address before reporting spam
check the formula used for jomega (scalar variables if I remember right), and check the formulation of the time and harmonic development of the PDE in the doc.
The time derivative is replaced by the -j*w (check the sign convention) where w = omega is 2*pi*f where f is the frequency, it should ring a bell w.r.t. Laplace development as used i.e. in control, no ?
Have fun Comsoling
Ivar
Please login with a confirmed email address before reporting spam
I have one question that think you might know the answer, as I saw you replied many of the questions in Comsol forum. I do appreciate if you can help me out with my problem.
I am trying to model ALE transient system in 3D as I attached the file, I was wondering if you cna help me to find out how can I fix the "shape function" problem with my file.
"s" [as I guess] is the shape function for 2D simulation, but for 3D modeling, I tried the same rules and it face to error.
would you please have a look at my files?
Best and thank you in advance
Yasaman
Please login with a confirmed email address before reporting spam
When simulating the microcantilever beam in water, did you apply the fluid-structure interaction boundary condition only on the top of the beam or on top and bottom? Thanks in advance!
Jin
Hi Teddy,
give a look to the pdf file: FSI Analysis of Microcantilevers Vibrating in Fluid Environment.
You find it in the "Paper & Presentations" section.
All models are in 3D but I think it is quite easy to convert them in 2d. No ale module is employed and all analyses are of "Damped Eigenfrequency" type.
I hope this helps.
Alessandro