Dynamics and sound emission of a spherical cavitation bubble in a dilute polymer solution

The effect of polymer additive on the growth and collapse of a spherical vapour bubble is investigated theoretically, under conditions appropriate for cavitation (negligible influence of heat transfer, Newtonian viscosity etc.). The polymer-induced stress is calculated using the yo-yo model of the polymer dynamics in transient extensional flows (Ryskin 1987a). The resulting equation of bubble dynamics is solved numerically an approximate analytical solution is also obtained. It is found that the growth of a bubble is not affected by the polymer, but the final stage of the collapse is. After following closely the classical inviscid-fluid solution, the collapse is abruptly arrested, and the bubble wall velocity is reduced to nearly zero. The peak acoustic pressure of the radiated sound is also reduced, and the high-frequency part of the acoustic spectrum is sharply curtailed.