双模态颗粒声凝并微观行为的数值模拟

考虑颗粒间多种相互作用机理及颗粒碰撞后的凝并与反弹机制，建立声凝并微观动力学模型，对大粒径外加颗粒及两个邻近的亚微米细颗粒之间的声凝并微观行为进行数值模拟研究。结果表明，双模态颗粒声凝并行为主要表现为外加颗粒仅与一个细颗粒发生凝并，以及外加颗粒先后与两个细颗粒发生凝并，声尾流效应、重力沉降作用是双模态颗粒声凝并的重要机理。随着外加颗粒初始位置与波节间距的增大，外加颗粒与较近细颗粒的平均凝并时间变化很小，两者形成的团聚体与较远细颗粒的平均凝并时间显著缩短；外加颗粒距离波节很近时，其仍能与较近的细颗粒发生凝并。对于外加颗粒与较近细颗粒以及两者形成的团聚体与较远细颗粒的凝并，随着外加颗粒直径的增加，平均凝并时间显著缩短，凝并概率先增加而后趋于恒定。

Numerical simulation on microscopic behavior of acoustic agglomeration of bimodal particles

A microscopic dynamic model for particle agglomeration was developed with simultaneous consideration of multiple particle interaction mechanisms as well as mechanisms of agglomeration or rebound upon inter-particle collision. The microscopic behaviors of acoustic agglomeration of a large-sized additional particle and its two neighboring submicron-sized fine particles were numerically investigated. The results show that the major acoustic agglomeration behaviors of the bimodal particles are characterized by the agglomeration between the additional particle and either fine particle and the successive agglomerate between the addition particle and the closer and farther fine particles. The gravitational effect and acoustic wake effect play an important role in the acoustic agglomeration of bimodal particles. When the distance between the initial position of the additional particle and wave node increases, small variation in the average agglomeration time between the additional particle and the closer fine particle is observed, whereas the average agglomeration time between the agglomerate formed by the said particles and the farther fine particle decreases obviously. When the additional particle is initially close to the wave node, it is possible for the particle to agglomerate with its closer fine particle. Concerning the agglomeration between the additional particle and its closer fine particle as well as the agglomerate formed by the said particles and the farther fine particle, the average agglomeration time increases while the agglomeration probability increases first and then tends to a constant value with the increasing additional particle diameter.