How to track interface in VOF, Please help!
 

Hello I have a 3D VOF model of an liquid/air system(droplet).

Does anybody know ho to track oscillations in the droplet. In my case I thought about using Y-directional velocity, but I dont know how to show it for the interface.

I want to monitor oscillations at the top point of the droplet.

Here is a cross-section:

http://de.tinypic.com/r/157irua/5

Please help,

thanks,
Mehmet