CAVITATION
There are four basic types of cavitation. Fundamentally cavitation results
from a drop in pressure on a liquid creates pockets or bubbles in the liquid -
an increase in pressure causes these bubbles to collapse resulting in a
tremendous "local" force which can cause damage to metals, emulsification, de-
gasification, sonoluminescence and many other strange and wonderous phenomena.
Bubble, Bubble, Toil and Trouble
The most important discovery in Hydraulics in the last 100 years, since the observation of Cavitation is: The Elimination of Cavitation!
from http://www-phys.llnl.gov/N_Div/sonolum/
About the LLNL sonoluminescence experiment
Sonoluminescence is the emission of light by bubbles in a liquid excited by sound. It was first discovered by scientists at the University of Cologne in 1934, but was not considered very interesting at the time.[1]
In recent years, a number of researchers have sought to understand this phenomenon in more detail. A major breakthrough occurred when Gaitan et al. were able to produce single-bubble sonoluminescence, in which a single bubble, trapped in a standing acoustic wave, emits light with each pulsation.[2] Before this development, research was hampered by the instability and short lifetime of the phenomenon.
