微小颗粒多相流布朗凝并过程的理论研究和数值模拟

Larger number of industrial emissions and automobile exhausts rich in tiny particulate matter are released into the atmosphere, which results in the increase of the number of particles in the atmosphere, and the environmental problems such as haze appear. Meanwhile, Brownian coagulation of small particles is one of the most important dynamics for small particles in the atmosphere. By means of numerical stimulation and theoretical analysis on the method of moments for Brownian coagulation of small particles, and numerical stimulation on particle Brownian coagulation process in particular flow fields, the project intends to achieve the following objectives: ①by approximately expressing the coagulation efficiency function by means of polynomial interpolation, propose a method of moments that is both computationally efficiency and accuracy; ②by using dimensional analysis method in the framework of log-normal preserved method of moments, propose new closing moment equations for Brownian coagulation in the near-continuum and transition regimes; ③by increasing the number of sections used in the sectional method, more accurately solve the multidimensional Brownian coagulation problems and more accurately reveal how the particle size distribution function evolves in different flow fields.

工业废气和汽车尾气等富含微小颗粒物质的污染气体排入大气后，会导致大气中的颗粒物不断增加，从而产生雾霾等环境问题。而微小颗粒布朗凝并现象又广泛存在于大气颗粒物的演化过程中。本项目拟通过对微小颗粒布朗凝并过程矩方法的理论和数值研究，以及对特定流场中微小颗粒布朗凝并过程的数值研究，达到以下目标：①利用多项式插值等近似方法处理凝并效率函数，构造兼顾计算效率和精度的高性能矩方法；②在对数正态分布矩方法的理论框架下，利用量纲分析方法，给出描述近连续区和过渡区布朗凝并过程的封闭矩方程；③提高分区方法中的分区数目，从而更加精确地求解多维微小颗粒布朗凝并问题，并更加准确地揭示不同流场中微小颗粒粒径分布函数的时空演化规律。