Ultrasonically Induced Fountains and Fogs

Experiments have demonstrated the feasibility of generating fountains and fogs over a body of water (see Figure 1) by utilizing high-intensity ultrasound to induce acoustic streaming, cavitation, and atomization. The transducer used in the experiments had a 10-cm diameter and a 10-cm focal length, was immersed in water at a depth approximately equal to its focal length, and was excited at various amplitudes and at various frequencies from 100 kHz to 2 MHz. It was observed in the experiments that the fountain and fog effects depend on the amplitude and frequency of excitation.