Crown breakup by Marangoni instability

We present experimental observations of hole formation in ejecta crowns, when a viscous drop impacts onto a thin film of low-viscosity liquid with significantly lower surface tension than the drop liquid. The holes are promoted by Marangoni-driven flows in the sheet, resulting from a spray of fine droplets ejected from the thin film hitting the inner side of the crown. The puncturing of the sheet takes place in three distinct steps. First a circular patch of the sheet thins by Marangoni-driven flows. Then this thinner film ruptures and a hole quickly opens up spanning the patch. Finally, the hole opens up further at an accelerated rate, driven by the unbalanced surface tension at its edge. The holes grow until they meet adjacent holes, thus leaving a foam-like network of liquid filaments, which then breaks up into a cloud of droplets.