标题： 液滴撞击冷颗粒单层的冻结延迟 显示英文标题

标题： Freezing delay of a drop impacting on a monolayer of cold grains

摘要： 我们研究了一种在低湿度环境中发生的低于冰点的液滴撞击情况，其中目标是一个冷的颗粒单层。当目标的过冷程度超过一个阈值时，与撞击下方的裸基底相比，这种颗粒层能有效推迟液滴的整体冻结时间。在这种情况下，液滴撞击后的回缩减少了与冷基底的接触面积，尽管颗粒和基底都对液体具有润湿性。我们发现，动态行为的显著变化是由润湿孔隙的液体冻结引发的。由于孔隙尺寸较小，冻结过程足够迅速，能够匹配液滴尺度上的动态过程。在某些情况下，快速冻结甚至可以阻止液体渗透并使冰层从下方表面脱落。 显示英文摘要

摘要： We investigate a subfreezing droplet impact scenario in a low-humidity environment, where the target is a cold granular monolayer. When the undercooling degree of targets passes a threshold, such a granular layer effectively postpones the bulk freezing time of the droplet in comparison with the impact on the bare substrate underneath. In this case, the retraction of the droplet after impact reduces the contact area with the cold substrate, even though both the grains and the substrate are wettable to the liquid. We find that the significant changes in the dynamic behavior are triggered by freezing the liquid that wets the pores. Owing to the small dimension of the pores, the freezing process is rapid enough to match the dynamics over the droplet dimension. In certain circumstances, the rapid freezing may even stop liquid penetration and shed icing from the underneath surface.