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:

http://www.cfd-online.com/Forums/mai...ng-comsol.html

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.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
simulation of liquid thin film	Saman	Main CFD Forum	4	March 11, 2018 00:55
Dynamic sloshing and hydrodynamic modeling of liquid storage tank for earthquake	K i M	Main CFD Forum	14	April 22, 2011 22:24
VOF problem, liquid film thickness	Pedro24	FLUENT	0	May 13, 2009 05:57
Liquid film	Trond G. Grüner	FLUENT	3	April 27, 2005 18:37
liquid film modeling	David Carnaga	Main CFD Forum	2	July 18, 2002 21:07

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.