Bifurcation of rotating liquid drops: results from USML-1 experiments in Space

Experiments on bifurcation of rotating liquid drops into two-lobed shapes were conducted during a Space shuttle flight. The drops were levitated in air and spinned using acoustic fields in the low-gravity environment. These experiments have successfully resolved the discrepancies existing between the previous experimental results and the theoretical predictions. In the simplest case of a rotating drop that is free from deformation by external forces, the results agree well with the existing theoretical predictions. In the case of a rotating drop subjected to flattening by the acoustic radiation stress, deliberately or otherwise, the experiments suggest the existence of a family of curves, with the free drop as the limiting case.