Micro cavitation bubbles on the movement of an experimental submarine   Theory and Experiments
  To further understand their nature, micro cavitation bubbles were systematically diffused around the exterior of a test body (tube) fully submerged in a water tank. The primary purpose was to assess the feasibility of applying micro cavitation as a means of depth control for underwater vehicles, mainly but not limited to submarines. Ideally, the results would indicate the use of micro cavitation as a more efficient alternative to underwater vehicle depth control than the conventional ballast tank method. The current approach utilizes the Archimedes' principle of buoyancy to alter the density of the object affected, making it less than, or greater than the density of the surrounding fluid. However, this process is too slow for underwater vehicles to react to sudden obstacles inherent in their environment. Rather than altering its internal density, this experiment aimed to investigate the response that would occur if the density of its environment was manipulated instead. In theory, and in a hydrostatic fluid, diffusing micro air bubbles from the top surface of the submarine would dilute the column of water above it with air cavities, thus lowering the density of the water. The resulting pressure differential would then cause the submarine to gain buoyancy. 
Stefan C. Mancas, Shahrdad G. Sajjadi, Asalie Anderson, Derek Hoffman
physics.flu-dyn