Oblate-prolate Faraday waves on a spherical drop: precession, torsion and symmetry breaking

When a spherical drop is subjected to an oscillating radial force, surface waves are excited whose pattern depends on the forcing frequency and amplitude. For frequencies leading to spherical harmonic degree $\ell=2$, the Faraday instability leads to a periodic oscillation between axisymmetric prolate and oblate shapes (Ebo-Adou et al. JFM 2019). We find that this regime is succeded by several further transitions: (1) precession of the drop, (2) breaking of axisymmetry leading to a general ellipsoid, and (3) torsion leading to elongation and rupture.