Rapid growth and collapse of single bubbles in polymer solutions undergoing shear.

Abstract

The dynamics of single bubbles were studied when the bubbles are generated by focussing the energy discharged from a Q switched laser into a small volume of dilute polymer solution undergoing shear between coaxial cylinders, one of which is rotating at a constant rate. Because of the shearing, the bubbles are non-spherical. The non-sphericity was reduced by approximately a factor of two when it was present at concentrations below 0.1% and the rate of shear in the fluid at the time of bubble inception was below 300 sec SUP - SUP 1. A bubble is formed from the laser discharge on a time scale of nanoseconds. Bubble growth and collapse occur in approximately 1 msec. Because the event occurs over such a short time, the results are relevant to the large alteration in cavitation behaviour which is observed when polymer is added to fluid flowing past a bluff body in a water tunnel. (A)