Coupled effects of hydrodynamic forces and pore structure on suspended particle transport and deposition in a saturated porous medium
Coupled effects of hydrodynamic forces and pore structure on suspended particle transport and deposition in a saturated porous medium
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DOI：
10.16285/j.rsm.2016.05.012
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发表时间：
2016-05-01
影响因子：
1.5
通讯作者：
Jiang Si-chen
中科院分区：
文献类型：
--
作者：
Zhang Peng-yuan;Bai Bing;Jiang Si-chen
为了研究孔隙结构和水动力对颗粒输运和沉积的影响，通过一系列柱试验研究了典型的二氧化硅粉末（悬浮颗粒）和荧光素（作为溶解示踪剂）在饱和多孔介质中的渗透过程.两种多孔介质（即，石英砂和玻璃珠）和5个渗透速度（即，0.033、0.066、0.132、0.199、0.265 cm/s），得到了20条穿透曲线。根据试验结果，分析了孔隙结构和渗流速度对悬浮颗粒在饱和多孔介质中沉积和运移过程的水动力学机理、弥散效应和加速效应的影响。结果表明，穿透曲线（BTC）是很好地描述了一级沉积动力学的对流-色散方程的解析解。与孔隙结构的影响相反，水动力过程对颗粒运移的影响随着渗流速度的增加而显著增加。存在一个临界渗流速度，超过该速度，悬浮颗粒的运动速度比溶解示踪剂的运动速度快，玻璃珠和石英的临界渗流速度不同。此外，两种多孔介质中颗粒的平均粒径、纵向弥散度和颗粒的回收率均随渗流速度的增大而增大，超过临界渗流速度后，颗粒的沉积率均随渗流速度的增大而减小。此外，即使孔隙率相似，悬浮颗粒的回收率在玻璃珠中也较高。总体而言，研究突出了孔隙结构和渗流速度对饱和多孔介质中颗粒运移的影响，且在高渗流速度条件下孔隙结构的作用更大。
To investigate the effects of pore structure and hydrodynamic forces on the particle transport and deposition, the penetration processes of a typical silica powder (suspended particles) and fluorescein (as the dissolved tracer) in saturated porous media is studied through a series of column tests. Two kinds of porous media (i.e., quartz sand and glass beads) and 5 seepage velocities (i.e., 0.033, 0.066, 0.132, 0.199, 0.265 cm/s) are considered, and twenty breakthrough curves are obtained. Based on the experimental results, the influence of pore structure and seepage velocity on the hydrodynamic mechanism, dispersion effects and accelerated effects are analyzed during deposition and migration processes of suspended particles in saturated porous media. It is shown that, the breakthrough curves (BTCs) are well described by an analytical solution of the advective-dispersive equation with a first-order deposition kinetics. In contrast with the effect of pore structure, the effect of hydrodynamics processes on particle transport increases significantly with the increase of seepage velocity. There exists a critical seepage velocity, beyond which suspended particles travel faster than the dissolved tracer, and the critical velocity is different for glass beads and quartz. In addition, the mean diameter of the recovered particles, the longitudinal dispersivity and recovery rate increase with the seepage velocity, and a decrease of the deposition rate of particles beyond the critical seepage velocity is also observed in two porous media. Furthermore, the recovery rate of suspended particles is higher in the glass beads even if the porosities are similar. Overall, the study highlights the effect of pore structure and seepage velocity on the transport of particles in saturated porous media, and the pore structure even plays a greater role in high seepage velocity conditions.