Paulovics David, Raufaste Christophe, Frisch Thomas, Claudet Cyrille, Celestini Franck
Université Côte d'Azur, CNRS, Institut de Physique de Nice (INPHYNI), 06100 Nice, France.
Institut Universitaire de France (IUF), 75005 Paris, France.
Langmuir. 2022 Mar 8;38(9):2972-2978. doi: 10.1021/acs.langmuir.1c03463. Epub 2022 Feb 23.
We investigate the process of condensation frosting on flat surfaces using thermal imaging microscopy. This method is particularly well-suited to characterize the frosting of polydisperse assemblies of dew droplets, also called breath figures, that transform into ice droplets by the propagation of frost fronts. The front propagation speed is found to be a nonmonotonous function of the characteristic droplet size of the breath figure. In our experimental conditions, the propagation speed is maximum around 70 μm s for a characteristic droplet radius of around 300 μm. We mainly show that the frost propagation speed is governed by the competition between two characteristic time scales. The first one is the freezing time of individual droplets, and the other one is the formation time of interdroplet ice bridges that grow from frozen to liquid droplets. In addition, the experiments reveal that the mean ice bridge speed is constant regardless of the characteristic radius of the liquid droplets in the breath figure. A theoretical mean-field analysis without any adjustable parameters recovers all of the features of the front propagation observed in experiments.
我们使用热成像显微镜研究平面上的凝结结霜过程。这种方法特别适合于表征多分散露珠集合体（也称为呼吸图案）的结霜情况，这些露珠会通过霜前沿的传播转变为冰滴。发现前沿传播速度是呼吸图案特征液滴尺寸的非单调函数。在我们的实验条件下，对于约300μm的特征液滴半径，传播速度在约70μm/s时最大。我们主要表明，霜的传播速度由两个特征时间尺度之间的竞争决定。第一个是单个液滴的冻结时间，另一个是从冻结液滴生长到液态液滴的液滴间冰桥的形成时间。此外，实验表明，平均冰桥速度与呼吸图案中液滴的特征半径无关，是恒定的。一种没有任何可调参数的理论平均场分析重现了实验中观察到的前沿传播的所有特征。
