The impact, freezing, and melting processes of a supercooled water droplet onto a cold slippery liquid-infused porous surface

In the present study, we report for the first time the observations of the impact, freezing, and melting processes of a supercooled water droplet onto a cold slippery liquid-infused porous surface (SLIPS). A parameter study of the droplet supercooling degree and the SLIPS temperature was carefully performed. Moreover, the impact process of a water droplet onto the SLIPS under the room temperature conditions was also measured for comparisons. The results showed that the impact kinematics of a water droplet on a SLIPS under the room temperature conditions was significantly different from those of the supercooled water droplet impinging onto a cold SLIPS. Under the same water droplet temperature conditions, the spreading factors rapidly increased to their maximum values at a similar rate, regardless of the change of the SLIPS temperature. Besides, under the same SLIPS temperature conditions, the maximum spreading factor of the water droplet at room temperature was significantly greater than those of the supercooled water droplet cases. When the temperatures of the water droplet and SLIPS were relatively high, freezing process started after the recoiling process had already finished for a certain period of time. However, when the temperatures of the water droplet and SLIPS were relatively low, freezing process could happen during the supercooled water droplet recoiling process. In addition, under the same water droplet temperature conditions, the decrease of the SLIPS temperature could result in the increase of the average energy dissipation rate of the water droplet.