Formation of vase-shaped drops

Vibrated substrates are useful tools to move and reshape drops. Experiments usually involve periodical excitation at small amplitude but new effects can be generated by using larger and/or quicker movements. Recently, impulsive motion of a plate has been shown to enhance drop takeoff. In this article we discuss the beautiful, elusive shapes obtained when a water droplet deposited on a nonwetting substrate is subjected to a strong vertical impulse. Drops are highly reshaped to form truncated cones that eventually collapse. We report and discuss the evolution of the geometrical features of these so-called "vase-shaped droplets". Our understanding of the physical phenomena at stake in the experiment allows us to model the evolution of the shape of the droplet. In particular, we show that the top and the bottom of the vase follow dynamics with different timescales, leading to the truncated cone shape. We show that it is possible to play with one of these dynamics by changing the wetting of the liquid on the rising substrate, and are thus able to change the shape of the vase from cylindrical to completely flat.