Contact line solidification of a spreading drop

Contact line dynamics of water advancing on a solid substrate below the freezing temperature is a today's challenging question. Despite its relevance in various applications, such as airplane icing or ice accretion on wires or roadways due to freezing rain, the fundamental mechanism of contact line arrest is still not fully understood. In this work, we investigate the spreading of a deposited water drop on a cooled substrate, for temperature ranging down to -45°C. By visualizing the growth of the dendritic patch formed in contact with the solid, we show how it pins the advancing contact line and arrests the drop spreading. Then, both dynamics of the contact line and the dendritic front are compared on the whole temperature range. These allow us to bring strong arguments in order to enlighten the debated mechanism on the contact line arrest due to solidification.