疏水冷面霜晶生长的有限扩散凝聚模型

DLA Model for Frost Crystal Growth on Hydrophobic Cold Surface

为了深入了解霜晶的动态生长过程,以有限扩散凝聚模型为基础建立了疏水冷面霜晶二维生长模型.通过在表面上设置不同冰珠数量来模拟冷面不同疏水性能,无涂层金属表面则布满冰珠;采用粒子在网格节点上随机移动来描述水蒸气分子的运动,粒子沿各方向移动的概率相同.数值结果表明,霜晶动态生长的可视化结果与实验图像在形态上保持一致;树枝状霜晶具有分形特征,相应的分形维数为1.44～1.78,与实验值相近.疏水冷面霜晶生长缓慢且分布稀疏;采用疏水效果不好的冷面的结霜情况与金属表面相似.

On the base of DLA （Diffusion-Limited Aggregation） model, a two-dimensional mathematical model was developed to describe the frost crystal growth on the hydrophobic cold surface in order to have a deep insight into the dynamic growth process of frost crystal. In this model, the surfaces with different ice beads were used to simulate the different hydrophobic surfaces, and the metal surface was covered with ice beads. The movement of the water-vapor molecule was described by the particle＇s movement in the grid-nodes, and the probability for the particle to move at each direction was the same. Numerical results showed that the predicted frost dynamic growth process of frost crystal conforms to the existed experimental result. The predicted dendritic frost crystal has the fractal structure, and its fractal dimension is between 1.44 and 1.78. Such results are in good agreement with the experimental data. The frost crystal grows up slowly and distributes sparsely on the hydrophobic cold surface, and the frost formation on the cold surface with bad hydrophobic coating is similar to that on the metal surface.