Droplet impacting and icing on supercooled surfaces frequently occurs in nature and in a variety of applications and may have catastrophic consequences. While the residual spreading diameter is more important than the maximum spreading diameter in most of applications, no attention was paid to its determination and to establishing its dependence on the surface temperature. The residual spreading diameter was investigated experimentally here. A threshold temperature was found below which the lamella formed by the impacting droplet freezes near the maximum spreading diameter, resulting in pancake-shaped freezing. While above the threshold temperature, the droplet retracts before freezing. The mechanisms responsible for these phenomena are described using a theoretical model which is compared with the experimental data. Results demonstrate that it is the heat transfer time that determines the threshold temperature.
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