三圆形颗粒在通道中沉降运动的数值研究

NUMERICAL STUDY ON THE SEDIMENTED MOTION CHARACTERISTICS OF THREE ALIGNED CIRCULAR PARTICLES IN THE INCLINED CHANNELS

主要应用浸没边界的格子玻尔兹曼方法 (immersed boundary-lattice Boltzmann method,IB–LBM)对处于不同倾斜角度通道内的三个刚体圆形颗粒在重力作用下下落的动力学特性进行了计算研究.首先分析通道倾斜角度的影响,结果显示当通道倾斜角处于59?～90?的范围时会发生后一个颗粒超越前一个颗粒的现象.其次,研究了Re对颗粒沉降特性的影响,结果表明Re越大,颗粒间发生聚集的时间越早.研究还发现当3个颗粒的直径大小不均匀时,颗粒由大到小纵向依次排列,或者出现中间小球直径较相邻两个小球直径大的排列情况,均能促使颗粒加快聚集.本文的研究结果可为环境工程及地质学中的颗粒沉降问题提供有价值的参考.

The immersed boundary-lattice Boltzmann method(IB-LBM) is used to numerically investigate the sedimented motion characteristics of three rigid circular particles in the inclined channels. The gravity is considered, and the inclined angles of the channels are sequentially changed from 0?to 90?. The effect of inclined angles on the sedimented motion characteristics is firstly investigated. Present results show that the lagging particle will surpass the leading particle when inclined angles of channel are larger than 59?. Then, the effect of Re number on the sedimented characteristics is also studied. This study finds that the aggregation time of three particles decreases as Re number increases. In addition, this study also finds that the non-uniformity of the diameters of three circular particles can alter the sedimented characteristics.When the diameters of three longitudinally aligned particles gradually become smaller, the aggregation time can be shorten. The aggregation of the particles can also be accelerated as long as the diameter of particles in the middle is larger than the diameters of other two adjacent particles. Present results can provide useful information for related problems in environmental engineering and geology.