A SPARK-GENERATED BUBBLE MODEL WITH SEMIEMPIRICAL MASS-TRANSPORT

This paper describes the time evolution of bubbles generated by underw ater electrical discharges. The oscillations of these high-temperature vapor and plasma bubbles generate acoustic signatures similar to the signatures generated by air guns, underwater explosions, and combustib le sources. A set of model equations is developed that allows the time evolution of the bubble generated by a spark discharge to be calculat ed numerically from a given power input. The acoustic signatures produ ced by the model were compared to previously recorded experimental dat a, and the model was found to agree over wide ranges of energy and amb ient pressure on several characteristic values of the acoustic signatu res. The bubble period in particular matched very well between model a nd experiment, indicating that the total energy losses predicted by th e model over the oscillation of the bubble were approximately correct, although no reliable information was gained about the relative magnit udes of the individual energy loss mechanisms examined. The bubble per iod and the minimum rarefaction pressure were found to depend on depth , while the peak pressures in the expansion and collapse pulses and th e acoustic energy in the expansion pulse were not found to depend on d epth over the parameter ranges investigated. (C) 1997 Acoustical Socie ty of America.