Dynamic Behavior of a Drop on a Vertically Oscillating Surface - Selected Topics of Computational and Experimental Fluid Mechanics - page 464

Fig. 1 Experimental set-up

2 Background

When a drop is subject to oscillating vertical forces, the changes of its geometry are
strongly dependent on the frequency.
These changes have been classified by previous authors taking into account some
characteristics of the pattern formation and the variation in time of its height as a
response to frequency changes (Noblin et al. 2009 ; Sudo et al. 2010 ).

3 Experimental Set-Up

The experimental set-up, shown in Fig. 1 , consists of a function generator connected
to a speaker over which an elasticmembrane is placed. Themembrane is coveredwith
Teflon, which is a hydrophobic material. A drop of water is placed on the membrane,
and its response is recorded by a high speed camera (Phantom Miro M310) and the
images analyzed in a computer with CINE Viewer.

4 Results

The geometry of the drop was recorded as the frequency was modified. Simultane-
ously, the side view of the drop was filmed and the height of its highest peak was
measured as a function of time.
Different types of patterns, named phases by some authors, were observed as the
frequency changed. The frequency interval for each phase is strongly dependent on
the volume of the drop.

4.1 Harmonic Phase

µ

Adropof60 1 of water was placed on the membrane. In a range of frequen-

cies between 1 and 31Hz the drop oscillates as a whole contracting and expanding