Vibrating Liquid Film - need help modeling

SpyderPride · July 4, 2011, 01:44

New to the forum, first post.

I am simply trying to model a small, thin volume of water that is contained horizontally and vibrating vertically. Approximate dimensions are something like 40 mm in diameter and 2 mm thick. I need to capture the parameters of the surface waves generated, namely the oscillating frequency, wavelength and velocity. The driving frequency I am considering right now is 300 Hz but would like to scale the model down even further for ultrasonic frequencies.

So far I have tried using different fluid elements in ANSYS (Fluid30, 80, etc) and I can't get any relevant results out of them. I have access to CFX and Fluent, have tried quite a bit in CFX but nothing useful so far.

I would greatly appreciate any advice, pointers to articles or books, or even some relevant terms that might help my search.

CFDtoy · July 7, 2011, 10:00

take a look at this thread:

acoustic cavitation modeling with COMSOL

ANSYS Fluent can do this pretty straight forward. I have placed a thesis reference as well.

Good luk.

/CFDtoy

Quote:

Originally Posted by CFD Expert

Hi,
have you used other software like SolidWorks, Cosmos or Hyper Mesh? i think these software will help you for modeling, if you still facing problems after using these software, you can ask more about your requirements at info@cfdanalysisservices.com

just ask your problems at given email and you will be answered by professionals.

Regards

SpyderPride · July 11, 2011, 12:54

I managed to get a model running in Flotran that *looks* decent, taking advantage of axisymmetry.

I know Flotran is very old, but I haven't been able to get anything going in Fluent (which is the only other solver I have access to now, no more CFX). I think my main problem with Fluent is creating the UDF for wall displacement motion. I can probably model this by making a rectangle with an edge on the y-axis, which will be the axis of symmetry. The bottom edge needs to oscillate up and down (y-direction), of the form y(t) = A*sin(w*t).

......................(air opening)
. -----------------------------------------------------
S |................................................. ...| No
Y |,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,| Slip
M |,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,| Wall
. -----------------------------------------------------
..........................y(t)

I can create the geometry, mesh it, set all the edges as separate regions, patch the water volume fraction in the lower 2/3 of the mesh, and set all the boundary conditions except the driving surface, which is currently a mystery to me.

Any advice would be appreciated.

July 4, 2011, 01:44	Vibrating Liquid Film - need help modeling	#1
SpyderPride New Member Join Date: Jul 2011 Posts: 2 Rep Power: 0	New to the forum, first post. I am simply trying to model a small, thin volume of water that is contained horizontally and vibrating vertically. Approximate dimensions are something like 40 mm in diameter and 2 mm thick. I need to capture the parameters of the surface waves generated, namely the oscillating frequency, wavelength and velocity. The driving frequency I am considering right now is 300 Hz but would like to scale the model down even further for ultrasonic frequencies. So far I have tried using different fluid elements in ANSYS (Fluid30, 80, etc) and I can't get any relevant results out of them. I have access to CFX and Fluent, have tried quite a bit in CFX but nothing useful so far. I would greatly appreciate any advice, pointers to articles or books, or even some relevant terms that might help my search.

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July 11, 2011, 12:54		#3
SpyderPride New Member Join Date: Jul 2011 Posts: 2 Rep Power: 0	I managed to get a model running in Flotran that looks decent, taking advantage of axisymmetry. I know Flotran is very old, but I haven't been able to get anything going in Fluent (which is the only other solver I have access to now, no more CFX). I think my main problem with Fluent is creating the UDF for wall displacement motion. I can probably model this by making a rectangle with an edge on the y-axis, which will be the axis of symmetry. The bottom edge needs to oscillate up and down (y-direction), of the form y(t) = Asin(wt). ......................(air opening) . ----------------------------------------------------- S \|................................................. ...\| No Y \|,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,\| Slip M \|,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,\| Wall . ----------------------------------------------------- ..........................y(t) I can create the geometry, mesh it, set all the edges as separate regions, patch the water volume fraction in the lower 2/3 of the mesh, and set all the boundary conditions except the driving surface, which is currently a mystery to me. Any advice would be appreciated.