外加声场对增加PM2.5碰撞几率的数值模拟研究

采用数值模拟方法对细粒子(PM2.5)在平面行波声场作用下的碰撞几率进行研究,基于直接模拟蒙特卡诺 (DSMC)方法的硬球模型研究PM2.5之间的碰撞。通过统计计算区域内PM2.5在一定时间内的碰撞次数,发现在外加声场作用下,PM2.5之间的碰撞几率与PM2.5浓度、声场强度及声波频率有显著关系。在声场保持不变的情况下,碰撞几率随PM2.5浓度的增大而增大;在PM2.5浓度和声波频率保持不变的情况下,碰撞几率随声场强度的增加而增大;在 PM2.5浓度和声场强度保持不变的情况下,碰撞几率随声波频率的增大,先增大后减小,存在一个使碰撞几率最大的最佳频率值。文章给出了碰撞几率与PM2.5浓度、声场强度、声波频率的关系曲线。

Numerical Simulation of the Collision Rate of PM2.5 in Sound Wave Field

Numerical method was used to study the collision rate of fine particles(PM2.5)in the plane traveling sound field. Based on the direct simulation Monte Carlo (DSMC) method of the hard sphere model, inter-particle collision property was investigated. Through counting the collision times of PM2.5 during a certain computing time at a research region, it is found that the collision rate has obvious relations with PM2.5 concentration, the sound intensity, and the sound wave frequency. The results show that the collision rate increases with the concentration of PM2.5 when the sound field keeps constant, and increases with the sound intensity while the concentration and the frequency remain same. It is also found that when the concentration and the sound intensity stay unchanging, the collision rate increases with the sound frequency at first and then begins to decrease, thus there is an optimum frequency that causes the highest collision rate. The relation curves between collision rate and the concentration, the sound intensity, and the frequency are given in the paper.