高Re数层流管道中颗粒聚集特性的数值研究

Numerical Investigation of Particle Focusing Patterns in Laminar Pipe Flow With High Reynolds Numbers

该文基于“相对运动模型”对高Re数层流管道中颗粒的惯性聚集特性进行了数值模拟.为了解决高Re数流长管道问题,对管道进、出口施加了周期性边界条件.研究结果表明,采用周期性边界条件可以有效地减小计算域,选用L=4D的管道便可计算出高Re数管流中颗粒的受力特性.与低Re数不同的是:随着Re数的不断增大,颗粒在径向上的升力不再呈类抛物线分布,升力曲线在r+=0.5~0.7之间出现一个下凹的区域,在这个区域内有出现新聚集点的趋势,并且用a+=1/17的颗粒在Re>1000时得到了这个新聚集点的位置.此外,通过对流场进行分析,发现颗粒的周围有二次流产生,其强度随着Re数的增大以及颗粒向壁面靠近逐渐增强,而二次流的产生影响了颗粒升力空间分布.

The inertial focusing characteristics of particles in laminar flow pipes with high Re numbers were studied based on the“relative motion model”.In order to solve the problem of long pipes with high Re number flow,periodic boundary conditions were imposed on the inlet and outlet of the pipe.The research results show that the use of periodic boundary conditions can effectively reduce the computational,and the mechanical properties of particles in high Re flow can be calculated by using L=4D pipe.The difference from the low Re number is that as the Re number continues to increase,the lift force of the particles in the radial direction is no longer distributed as a parabola.The lift curve has a concave area between r+=0.5~0.7,and there is a tendency for a new inertial focus point to appear in this section.By means of particles of a+=1/17 for Re>1000,this new focus point position is solvable.In addition,in the analysis of the flow field,a secondary flow occurs around the particle,and its intensity gradually increases with the Re number and the closeness of the particle to the wall.The generation of the secondary flow affects the spatial distribution of the particle lift.