Local spiky contacts during impact of an emulsion drop on a solid surface

We study the first contact of an emulsion drop impacting on a smooth solid surface. The lubricating air layer causes rapid deceleration of the bottom tip of the drop as it approaches first contact, causing a dimple in the drop surface. When the dispersed emulsion droplets are of higher density than the drop's continuous phase, the rapid deceleration ( ${\sim }10^5$ m s $^{-2}$ ) induces the formation of narrow spikes extruding out of the free surface. These spikes form when the impact Weber number exceeds a critical value ${\simeq }10$ . Time-resolved interferometric imaging, at rates up to 7 million frames per second, shows the emergence and shape of these spikes leading to the local contacts with the solid. We characterize the tip curvature and capillary pressure affecting their dynamics as they emerge and can touch the substrate before the main outer ring of contact.