Droplet Motions Fill a Periodic Table

Droplet motions are widely observed yet still poorly understood.  Despite more than a century of study, the spectrum of the vibrating spherical-cap drop has only recently been published.  Like that of the chemical elements, the quantization of inviscid droplet motions arises due to restriction to standing waves. In the droplet case, the standing waves result from constraints on the interface by wetting conditions:  the static contact-angle and the contact-line mobility.  The linear stability of a sessile droplet is determined by a Schroedinger-like equation and the spectra of mode shapes fill a periodic table much like that of the chemical elements. In this talk we present the periodic table and illustrate benefits of recognizing the spectral structure and the periodic table analogy.