Acoustic Fountain Effect

An intense standing sound wave along the free surface of a liquid produces a static deformation of the surface and in certain cases stationary fountains. This phenomenon has been known for a long time [V. Dvorak, Ann. Physik 7, 42 (1876)]. We have measured the acoustic threshold of fountain formation in different liquids and propose an explanation for this instability. [This work was supported by the ONR, under contract.]