摘要
应用大涡模拟方法求解平面湍射流场,矩方法求解纳米粒子的一般动力学方程.通过对每种情况3000个时间步的平均,得到了Schmidt数和Damkohler数对纳米粒子动力学特性的影响.结果发现,当气体参数不变时,Schmidt数的变化只对直径小于1 nm的颗粒数密度的分布产生影响.直径小的颗粒其颗粒数密度沿流动方向下降迅速,而具有大Schmidt数的颗粒,沿横向的分布较窄.较小的颗粒容易发生积聚和扩散,并且体积增长较快,因而颗粒多分散性较为明显.小的颗粒积聚时间尺度能增强颗粒的碰撞和积聚频率,导致颗粒尺寸迅速增大.Damkohler数越大,颗粒的多分散也越明显.
Large eddy simulations of nanopartiele coagulation in an incompressible planar jet were performed. The particle is described using a moment method to approximate the particle general dynamics equations. The time-averaged results based on 3 000 time steps for every case were obtained to explore the influence of the Schmidt number and the Damkobler number on the nanoparticle dynamics. The results show that the changes of Schmidt number have the influence on the number concentration of nanoparticles only when the particle diameter is less than lnm for the fixed gas parameters. The number concentration of particles for small particles decreases more rapidly along the flow direction, and the nanoparticles with larger Schmidt number have a narrower distribution along the transverse direction. The smaller nanoparticles coagulate and disperse easily, grow rapidly hence show a stronger polydispersity. The smaller coagulation time scale can enhance the particle collision and coagulation. Frequent collision and coagulation bring a great increase in particle size. The larger the Damkohler number, the higher the particle polydispersity.
出处
《应用数学和力学》
CSCD
北大核心
2007年第11期1287-1295,共9页
Applied Mathematics and Mechanics
基金
科技部重大基础研究前期研究专项资助项目(2005CCA06900)
关键词
纳米粒子
积聚
平面射流
矩方法
大涡模拟
nanoparticle
coagulation
planar jet
moment method
large eddy simulation
