In the present work, an investigation of stagnation flow imposed on a supercooled water drop in cold environmental conditions was carried out at various air velocities ranging from 0 (i.e., still air) to 10 m/s along with temperature spanning from ?10 to ?30 °C. The net effect of air flow on the impacting water droplet was investigated by controlling the droplet impact velocity to make it similar with and without air flow. In cold atmospheric conditions with temperatures as low as ?30 °C, due to the large increase of both internal and contact line viscosity combined with the presence of ice nucleation mechanisms, supercooled water droplet wetting behavior was systematically affected. Instantaneous pinning for hydrophilic and hydrophobic surfaces was observed when the spread drop reached the maximum spreading diameter (i.e., no recoiling phase). Nevertheless, superhydrophobic surfaces showed a great repellency (e.g., contact time reduction up to 30% where air velocity was increased up to 10 m/s) at temperatures above the critical temperature of heterogeneous ice nucleation (i.e., ?24 °C). However, the freezing line of the impacting water droplet was extended up to 2-fold at air velocity up to 10 m/s where substrate temperature was maintained below the aforementioned critical temperature (e.g., ?30 °C).
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机译：在目前的工作中，研究了在寒冷的环境条件下，过冷水滴在从0（即静止空气）到10 m / s的各种风速以及从10到0的温度范围内的停滞流的研究。 30°C。通过控制液滴的撞击速度，使其在有或没有空气流的情况下相似，研究了气流对撞击水滴的净影响。在温度低至≤30°C的寒冷大气条件下，由于内部和接触线的黏度大大增加，并且由于存在冰核机制，系统地影响了过冷水滴的润湿性能。当铺展液滴达到最大铺展直径时（即，没有反卷相），观察到亲水和疏水表面的瞬时钉扎。然而，在高于非均质冰核形成的临界温度（即≥24℃）的温度下，超疏水表面显示出很大的排斥性（例如，接触时间减少高达30％，其中空气速度增加至10m / s）。但是，冲击水滴的冻结线在风速高达10m / s的情况下延伸至2倍，此时基板温度保持在上述临界温度（例如≤30℃）以下。
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