In other words, with insufficient pressure to hold them together, the liquid water molecules dissociate into a gas. When required, another gas can be injected into these cavities which increases their size, a situtation which we call an artificial or ventilated cavity. Supercavitation is an extreme version of cavitation in which a single bubble or supercavity is formed that envelopes the moving object almost completely. With slender axisymmetric bodies, supercavities take the shape of elongated ellipsoids beginning at the blunt forebody and trailing behind, with the length dependent on the speed of the body, he says. The resulting elliptically shaped cavities soon close up under the pressure of the surrounding water.
Gravity tends to cause the gas cavity to float upwards.
Naval architects and marine engineers typically try to avoid cavitation because it can distort water flow to rob pumps, turbines, hydrofoils, and propellers of operational efficiency. Finally, supercavitation occurred behind the foils, which halted normal water flow over them, substantially reducing their hydrodynamic function. Tulin was instrumental in engineering blade shapes that overcame many of these problems. Since then, further application of mathematical modeling and analysis techniques has proved highly fruitful. Important work by D. Riabouchinsky, G. V. Logvinovich, L. A. Epshtein, Egorov, et.al.