论文标题
悬浮液在压力驱动流中和通过多孔结构中的粒子迁移
Particle migration of suspensions in a pressure-driven flow over and through a porous structure
论文作者
论文摘要
进行了实验室实验，以研究非棕色，非胶体悬浮液的粒子迁移和流动性能，范围从较低的雷诺数下的多孔结构上下的压力驱动流动中的粒子体积分数范围为10％至40％。使用磁共振成像（MRI）技术获取粒子浓度图，速度图和相应的轮廓。模型多孔培养基由矩形微通道中流动跨流的圆形杆的平方阵列组成。据观察，圆形杆的平方阵列会改变速度曲线，并导致各种悬浮液的异质浓度场。随着悬浮液的大量颗粒体积分数增加，颗粒倾向于相对于多孔介质集中在自由通道中，而沿着侧向的中心线速度曲线越来越钝化。在多孔结构中，与半稀释悬浮液相比，由于几何形状引起的浓缩悬浮液显示出较小的周期性轴向速度变化（散装体积分数在10％至20％之间），并且显示周期浓度变化，其中平均颗粒浓度在杆之间的平均颗粒浓度略大于杆的顶部。对于浓缩系统，在与多孔介质内杆之间间隙相对应的区域中观察到与流动方向排列的高颗粒浓度途径。
Laboratory experiments were conducted to study particle migration and flow properties of non- Brownian, non-colloidal suspensions ranging from 10% to 40% particle volume fraction in a pressure-driven flow over and through a porous structure at low Reynolds number. Particle concentration maps, velocity maps and corresponding profiles were acquired using a magnetic resonance imaging (MRI) technique. The model porous medium consists of square arrays of circular rods oriented across the flow in a rectangular microchannel. It was observed that the square arrays of the circular rods modify the velocity profiles and result in heterogeneous concentration fields for various suspensions. As the bulk particle volume fraction of the suspension increases, particles tend to concentrate in the free channel relative to the porous medium while the centerline velocity profile along the lateral direction becomes increasingly blunted. Within the porous structure, concentrated suspensions exhibit smaller periodic axial velocity variations due to the geometry compared to semi-dilute suspensions (bulk volume fraction ranges from 10% to 20%) and show periodic concentration variations, where average particle concentration is slightly greater between the rods than on top of the rods. For concentrated systems, high particle concentration pathways aligned with the flow direction are observed in regions that correspond to gaps between rods within the porous medium.
