The experimental observation of the behavior of acoustically rotated free drops in the microgravity environment of low earth orbit has yielded the first data which meet the restrictions of existing theoretical treatments. Rotating drops displayed both ‘‘axisymmetric’’ and ‘‘two-lobed’’ shapes in the presence and absence of applied torques. Their dimensions and general development confirm the existence of the distinct shape families and the bifurcation point between them. The data also indicate that the secular instability in the axisymmetric family occurs at a lower rotation velocity than predicted.

• Received 14 November 1985

DOI:https://doi.org/10.1103/PhysRevLett.56.452