Abstract
The shape of a rising bubble in static non-Newtonian media was presented and discussed in many articles.As for the relation between moving direction and symmetrical axis of the bubbles,most of experimental results show the same direction with the exception that the axis of bubble wobbles slightly in a certain condition.In the case under pressure-oscillating field in 0.8wt% SPA liquid at 300Hz,the cusped shape appears cyclically,in which the 1μL bubble is compressed and rising much faster than its natural rising velocity.However,the moving direction and symmetrical axis are the same.In this study,we observed motion of a 1.8μL bubble in 6wt% CMC liquid under pressure-oscillating field by use of a couple of synchronized high-speed cameras attached to microscopes,respectively.We found that as increasing in pressure-oscillation,the shape of rising bubble changes from spherical to vertically aligned oblate ellipsoid,in which the symmetrical axis is stably horizontal and the axis rotates slowly.
