【摘要】 针对方管中中性悬浮颗粒(颗粒与流体密度等于1)的惯性迁移现象问题,采用并行虚拟区域方法(DF/FD)进行了完全直接数值模拟。选取了周期性管长(L=2H)和3种不同粒径大小的球形颗粒,模拟研究了颗粒在Re为100~1 500范围内的方腔管道中的惯性迁移过程,确定了颗粒的迁移轨迹和平衡位置,以及粒径对颗粒惯性迁移现象的影响,并与圆管、槽道流结果进行了对比。研究结果表明:颗粒迁移后的平衡位置主要分为方管对角线和边线中间两种;随着雷诺数的增加,对角线上的平衡位置愈靠近角落,颗粒粒径越小,离角落越近;边线中间的平衡位置则先靠近壁面,当Re增加到800左右,颗粒的平衡位置开始远离壁面向方管中心迁移,大颗粒即粒径比a/H=0.15表现的最为明显,会形成类似于圆管中的内部平衡位置。更多还原

【Abstract】 In order to study the inertial migration of neutrally buoyant particles( ρr= 1) in a square duct,a parallel direct-forcing fictitious domain method was employed to perform fully-resolved numerical simulations. With the duct length( L = 2H) and spherical particles of three different diameters,the migration trajectory and equilibrium positions at the bulk Reynolds number from 100 to 1 500 were investigated and compared to the result of the pipe and channel. The effects of the particle diameters on the inertial migration were acquired. The results indicate that particles migrate to two main different kinds of equilibrium positions: one at the diagonal line near the corner and the other at the middle of center line. With the increasing of the Re,on one hand,the equilibrium position at the diagonal line becoms closer to the corner, besides the smaller the particle becomes,the closer to the corner; on the other hand,the equilibrium position at the center line tends to the wall first and then leaves the wall tending to the center while the Re increased to around 800. Comparatively the smaller the particle is,the closer to the wall the equilibrium positions is. Especially for the largest particle( a / H = 0. 15),the equilibrium position is similar to the tube’s inner equilibrium position.更多还原