  The spherical dynamics of a bubble in a compressible liquid has been studied
extensively since the early work of Gilmore. Numerical codes to study the
behavior, including when large non-spherical deformations are involved, have
since been developed and have been shown to be accurate. The situation is
however different and common knowledge less advanced when the compressibility
of the medium surrounding the bubble is provided mainly by the presence of a
bubbly mixture. In one of the present works being carried out at DYNAFLOW,
INC., the dynamics of a primary relatively large bubble in a water mixture
including very fine bubbles is being investigated experimentally and the
results are being provided to several parallel on-going analytical and
numerical approaches. The main/primary bubble is produced by an underwater
spark discharge from two concentric electrodes placed in the bubbly medium,
which is generated using electrolysis. A grid of thin perpendicular wires is
used to generate bubble distributions of varying intensities. The size of the
main bubble is controlled by the discharge voltage, the capacitors size, and
the pressure imposed in the container. The size and concentration of the fine
bubbles can be controlled by the electrolysis voltage, the length, diameter,
and type of the wires, and also by the pressure imposed in the container. This
enables parametric study of the factors controlling the dynamics of the primary
bubble and development of relationships between the bubble characteristic
quantities such as maximum bubble radius and bubble period and the
characteristics of the surrounding two-phase medium: micro bubble sizes and
void fraction.
