颗粒群研究:多相流多尺度数值模拟的基础

Knowledge on Particle Swarm: The Important Basis for Multi-scale Numerical Simulation of Multiphase Flows

用两流体模型及颗粒轨道模型数值模拟过程工程设备中的多相流,都需要表达浓度较高的分散相和连续相间的作用力的本构方程.本工作综述了多相流中颗粒受力研究的现状和尚待解决的问题.对单个颗粒(包括流体颗粒)在静止和运动流体中的受力情况的研究结果比较丰富,但对颗粒群的研究则很不充分.对颗粒受的曳力研究较多,但还缺乏可信的计算升力、非稳态力等的公式.因此颗粒群的研究成为多相流准确多尺度数值模拟的关键.开发能处理整体和局部均存在非均匀性的多相流的高效算法也是有待克服的困难.

Numerical simulation of multiphase flows in processing equipment in process industry with two-fluid model and Eulerian-Lagrangian approach requires the constitutive equations describing the interactions between the dispersed phase of high concentration and the continuous phase. The status of research on the forces on solid and fluid particles and the topics remaining to be tackled are reviewed. As compared with the knowledge on drag of single solid particles, study on particle swarms and on other forces is not sufficient to meet the needs of numerical simulation of multiphase flows. Thus, thorough study on the particle swarms and clusters becomes the key to accurate multi-scale simulation of multiphase flows. Besides, the development of efficient algorithm dealing with the simultaneous non-uniformity on equipment and mesoscopic scales is recognized as an important issue to be resolved.