The phenomenon of cavitation was first recognized in 1885 during the sea trials of HMS Daring when, due to the previously unmatched propeller speeds, it was noted that ‘… cavities were being formed in the water … and these were the source of a great waste of power and the cause of other difficulties'. This paper will begin by briefly reviewing the history of cavitation phenomena and will end with a vision of the new horizons for the amazing cavitation bubble.
By creating cavitation bubbles non-invasively thereby depositing and focusing energy non-intrusively, one can generate minute incisions or target cancer cells. Cavitation bubbles are now used in a remarkable range of surgical and medical procedures, for example to emulsify tissue (most commonly in cataract surgery or in lithotripsy procedures for the reduction of kidney and gall stones) or to manipulate the DNA in individual cells. But, harnessed carefully, this almost unique ability to focus energy can also be put to remarkably constructive use.
In perhaps the most extraordinary example of energy focusing, collapsing cavitation bubbles can emit not only sound, but also light with black body radiation temperatures equal to that of the sun (Brennen 1995 Cavitation and bubble dynamics). In liquid-propelled rocket engines, bubbles pose a danger to the stability of the propulsion system, and in artificial heart valves they can cause serious damage to the red blood cells. In other contexts that focusing of energy can lead to serious technological problems as when cavitation bubbles eat great holes through ships' propeller blades or cause a threat to the integrity of the spillways at the Hoover Dam. But even these mundane effects are examples of the ability of bubbles to gather, focus and radiate energy (acoustic energy in the above examples). Some of those effects are the stuff of our everyday experience as in the tinkling of a brook or the sounds of breaking waves at the beach. We generally think of bubbles as benign and harmless and yet they can manifest the most remarkable range of physical effects.
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