Solidification during impact: freezing the shape of a splash

The impact of a drop on an immiscible bath can generate different patterns depending on several parameters including the initial velocity of the drop and the density difference with the liquid bath. If the impacting drop can readily solidify upon cooling, the shape of the splash can be frozen in time. In this work, we study the morphologies obtained upon impacting a hot solution of paraffin wax in mineral oil on a cold immiscible bath. As it cools down, the impacting drop solidifies during the complex deformation processes associated with splashing, generating different morphologies that vary from cup-like to floral shapes with increasing number of petals. The anatomy of the final solidified wax is the result of a competition between different physical processes and instabilities that all occur over the time-scales of impact, including droplet breakup, wrinkling and crack formation /propagation in a thin stretched elastic sheet. Using high-speed imaging we show how different control parameters affect these fascinating morphologies that span the range from transient pattern formation in deforming fluids to the permanent indelible shape of thin elastic solid shells.