双颗粒沉降的动力学分析

采用格子Boltzmann-虚拟区域方法对雷诺数范围为50≤Re≤200的双颗粒自由沉降进行了直接数值模拟。首先,研究发现双颗粒最终沉降的位置分别在通道的1/4和3/4位置附近,且与颗粒的初始间距、雷诺数以及通道宽度无关。其次,重点研究了颗粒沉降过程中所受的侧向力(与沉降方向垂直),首次揭示了侧向力的振动频率与雷诺数呈二次关系,且单颗粒的结果始终小于双颗粒的结果;研究还发现侧向力的振动频率与通道宽度近似呈幂律函数关系,且幂律指数与雷诺数有关,雷诺数越大,幂律指数的绝对值越小。最后还研究了雷诺数及通道宽度对侧向力振动振幅的影响。

Dynamic analysis of two settling particles in a channel

The lattice Boltzmann‐direct forcing/fictitious method has been used to simulate the sedimenta‐tion of two particles in a channel for the Reynolds number of 50≤ Re ≤200 .First of all ,it has been shown that the two particles eventually sedimenting at 1/4 and 3/4 of channel width ,respectively ,irre‐spective of initial particle distance ,Reynolds numbers and channel width .Secondly ,the lateral forces (perpendicular to gravity ) experienced by the particles are examined in detail .It has been found that the frequency of the lateral forces increases quadratically with increased Reynolds number .Furthermore ,the frequency of single‐particle system is always smaller than that of two‐particle system .The significant power‐law relationship between the frequency and the channel width has also been found through numer‐ical simulations .The power‐law exponent depends on the Reynolds number .The larger the Reynolds number is ,the smaller the absolute value of the exponent is .Moreover ,the influence of the Reynolds number and channel width on the amplitude of the lateral forces is also studied in this work .