关键词: 过冷水, 冰, 温度, 应力, 分子动力学模拟

Abstract: The physical process of supercooled large droplet impingement freezing is complex, involving the coupling of droplet impact dynamics and solidification process, among which the influence of temperature and stress on ice nucleus for-mation and growth has received widespread attention. In this paper, the molecular dynamics simulation method is employed to establish homogeneous nucleation and heterogeneous nucleation models for the freezing problem of supercooled water at different temperatures, and the natural freezing and ice nucleation freezing processes are stud-ied. Firstly, the radial distribution function characteristics were analyzed after the freezing fraction reached 70%. It is preliminarily determined that when the radial distribution function of the research object is consistent with cubic ice and the deviations at the two peaks at 2.7? and 4.4? are less than 10% and 20% respectively, it can be used as a basis for judging the freezing phenomenon. Then, the critical number of ice nuclei at different temperatures is calcu-lated, which is consistent with the critical number of cubic ice nuclei given by the classical nucleation theory at tem-peratures below 250K. On this basis, load stress is introduced to study its influence on the icing process. The results of this paper show that under the action of shear load with a strain rate of 2.4*107s-1 and triaxial compression load with a strain rate of 2*105s-1 to 2*103s-1, the nucleation and growth of ice are promoted. The nucleation process is mainly due to the competition between the hindering effect caused by the increase of nucleation barrier and the promoting effect caused by the increase of self-diffusion rate, and the growth process is mainly attributed to the promoting effect caused by the increase of self-diffusion rate.

Key words: Supercooled water, Ice, Temperature, Stress, Molecular dynamic simulation