Particle-scale modelling of fluid velocity distribution near the particles surface in sand filtration.,Water Research

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Particle-scale modelling of fluid velocity distribution near the particles surface in sand filtration.
Water Research ( IF 11.4 ) Pub Date : 2020-04-02 , DOI: 10.1016/j.watres.2020.115758
Shuang Song ₁ , Liangwan Rong ₂ , Kejun Dong ₃ , Xuefei Liu ₄ , Pierre Le Clech ₁ , Yansong Shen ₁

Affiliation

Sand filtration is widely used in drinking water treatment processes, yet the hydraulic fundamentals at particle-scale are not well defined, especially the fluid velocity profile near the sand particles surface. In this study, a numerical model is developed by combining the Lattice Boltzmann (LBM) and the Discrete Element Method (DEM), used to describe the fluid flow over the sand particles surface and the micro-structure details of the sand packed bed respectively. The model is validated by comparing the simulation results with the experimental measurements using two systems, showing that the model can describe the fluid velocity distribution around the particles surface. Critical flow velocity is introduced as the balance between hydrodynamic and adhesive torques acting on sand particle surface. Furthermore, a new concept - effective filter surface (EFS), is defined as the area where the velocity near sand particles surface is less than the critical flow velocity, aiming for indirectly evaluating the performance of sand filtration. It is quantitatively demonstrated that increasing the sand particle size or feed flow velocity results in the decrease of both critical flow velocity and EFS under the given tested conditions. The LBM-DEM model provides a useful tool for understanding the fundamentals of liquid flow distribution and also estimating sand filtration performance under different operation conditions.

中文翻译：

砂滤中颗粒表面附近流体速度分布的颗粒模型。

砂滤广泛用于饮用水处理过程中，但在粒度范围内的水力基本原理尚不明确，尤其是砂粒表面附近的流速分布。在这项研究中，通过结合格子Boltzmann（LBM）和离散元素方法（DEM）建立了一个数值模型，用于分别描述流过砂粒表面的流体和填充砂床的微观结构细节。通过将仿真结果与使用两个系统的实验测量值进行比较来验证该模型，表明该模型可以描述粒子表面周围的流体速度分布。引入临界流速作为作用在砂粒表面上的流体动力和粘附扭矩之间的平衡。此外，一个新概念-有效过滤器表面（EFS）被定义为砂粒表面附近的速度小于临界流速的区域，旨在间接评估砂子过滤的性能。定量证明，在给定的测试条件下，增加砂粒尺寸或进料流速会导致临界流速和EFS降低。LBM-DEM模型提供了一个有用的工具，可用于了解液体流量分布的基本原理以及估算不同操作条件下的砂滤性能。定量证明，在给定的测试条件下，增加砂粒尺寸或进料流速会导致临界流速和EFS降低。LBM-DEM模型提供了一个有用的工具，可用于了解液体流量分布的基本原理以及估算不同操作条件下的砂滤性能。定量证明，在给定的测试条件下，增加砂粒尺寸或进料流速会导致临界流速和EFS降低。LBM-DEM模型提供了一个有用的工具，可用于了解液体流量分布的基本原理以及估算不同操作条件下的砂滤性能。

更新日期：2020-04-03

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