Is the maximum water droplet diameter fixed by the capillary length?*

Water droplet break-up has been studied extensively but typically focuses on droplets with radii near the capillary length (< 3 mm). Droplets larger than this typically break-up when their velocity approaches terminal velocity, with larger droplets breaking up well before they reach terminal speeds. In general, studies involving large droplet break-up are scarce and part of the reason is the difficulty performing such experiments. We propose a method to suspend droplets of radii up to 60 mm using a series of release mechanisms and release speeds to illustrate the complexity and parameter space for practical solutions to these problems. The research details the effects of release acceleration, surface geometry and surface features on the initial droplet perturbations. Droplet perturbations are recorded with high speed imaging and are used to determine what oscillation frequencies and modes are present in the falling droplet. Analysis of the droplet frequencies and amplitudes reveals five major mode types. Droplet volume predicts the frequencies in accordance with Rayleigh theory. The best shape and acceleration of release are presented.