Sound of Single Vapor Bubbles

The recent preliminary acoustic measurements of single vapor bubbles on a heated platinum wire, combined with high-speed digital photography, provided significant information for the vapor bubble dynamics such as growth, departure, collapse or coalescence with a previous bubble. Furthermore, under a given condition, the numerous consecutive single bubbles consistently showed almost identical waveforms, even at different times. This surprising result indicates that the phenomenon is not a chaotic process, but an orderly mathematical process. The deceleration of a growing bubble following the rapid initial growth was apparently detected by the acoustic emissions as a negative acoustic pressure. This is believed to be a new observation and not seen in gas bubbles. Some successive bubbles clearly underwent the spherical harmonics and compared well with a series of photographs. These results are in contrast with the previous indeterminate measurements on the sound intensity and frequency in boiling in the literature. The information for vapor bubble dynamics will be supplementary to the gas bubble dynamics such as cavitation, sonoluminescence, etc. Visual observations will be valuable for the mathematicians who study the spherical harmonics analytically. Also, the technique and information may be applicable to the fields of science and engineering associated with vapor bubbles motion including boiling.