A liquid drop placed on a vibrating diaphragm will burst into a fine spray of
smaller secondary droplets if it is driven at the proper frequency and amplitude. The
process begins when capillary waves appear on the free surface of the drop and then
grow in amplitude and complexity as the acceleration amplitude of the diaphragm
is slowly increased from zero. When the acceleration of the diaphragm rises above
a well-defined critical value, small secondary droplets begin to be ejected from the
free-surface wave crests. Then, quite suddenly, the entire volume of the drop is ejected
from the vibrating diaphragm in the form of a spray. This event is the result of an
interaction between the fluid dynamical process of droplet ejection and the vibrational
dynamics of the diaphragm. During droplet ejection, the effective mass of the
drop–diaphragm system decreases and the resonance frequency of the system increases. If
the initial forcing frequency is above the resonance frequency of the system, droplet
ejection causes the system to move closer to resonance, which in turn causes more
vigorous vibration and faster droplet ejection. This ultimately leads to drop bursting.
In this paper, the basic phenomenon of vibration-induced drop atomization and drop
bursting will be introduced, demonstrated, and characterized. Experimental results
and a simple mathematical model of the process will be presented and used to explain
the basic physics of the system.