应力和温度对过冷水结冰影响的分子动力学模拟

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 formation and growth has received widespread attention. The molecular dynamics simulation method is em ⁃ ployed to establish homogeneous nucleation and heterogeneous nucleation models for the freezing problem of super⁃ cooled water at different temperatures, and the natural freezing and ice nucleation freezing processes are studied. First, the radial distribution function characteristics are analyzed after the freezing fraction reached 70%. It is prelimi⁃ narily determined that when the radial distribution function of the research object is consistent with cubic ice and the de ⁃ viations at the two peaks at 2. 7X1Q−10 m and 4. 4x10−10 m 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 for heterogeneous nucleation models at different temperatures is calculated, which is consistent with the critical number of cubic ice nuclei given by the classical nucleation theory at temperatures below 250 K. On this basis, load stress is introduced to study its influ ⁃ ence on the icing process. The results of this paper show that under the action of different load, the strain rates pro⁃ moting nucleation and growth of ice are different. The shear strain rate is 107 108 s−1, and the triaxial compression strain rate is 105 106 s−1. The nucleation process of ice 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 of ice nuclei is mainly attributed to the promoting effect caused by the increase of self-diffusion rate.