在各类工程中产生了大量的高含水率废弃泥浆,过滤分离技术逐渐应用于泥浆的快速减量化中。为明确泥浆过滤的微观过程及堵塞机理,建立并验证了利用格子玻尔兹曼方法-离散单元法(Lattice Boltzmann method-discrete element method,LBM-D...在各类工程中产生了大量的高含水率废弃泥浆,过滤分离技术逐渐应用于泥浆的快速减量化中。为明确泥浆过滤的微观过程及堵塞机理,建立并验证了利用格子玻尔兹曼方法-离散单元法(Lattice Boltzmann method-discrete element method,LBM-DEM)模拟泥浆过滤。采用LBM-DEM方法模拟了多类条件下泥浆的过滤,包括不同泥浆含水率、过滤介质孔径、过滤压力及絮团性质。实验结果表明:泥浆在过滤过程中,过滤介质先作为主要的过滤单元,颗粒(或絮团)不断堵塞在过滤介质中或发生流失,当过滤介质完全堵塞后,颗粒(或絮团)不再发生流失,逐渐堆积在过滤介质表面,随着过滤的进行,泥皮逐渐累积增厚;堵塞完成的过滤介质及不断增厚的泥皮的组合体成为新的过滤系统。泥皮的渗透系数决定了新过滤系统的渗透能力,是影响泥浆过滤脱水的主要因素。LBM-DEM新方法的建立为研究及优化泥浆过滤效率提供了借鉴以及新的思路。展开更多
This paper investigates the effect of initial volume fraction on the runout characteristics of collapse of granular columns on slopes in fluid. 2-D sub-grain scale numerical simulations are performed to understand the...This paper investigates the effect of initial volume fraction on the runout characteristics of collapse of granular columns on slopes in fluid. 2-D sub-grain scale numerical simulations are performed to understand the flow dynamics of granular collapse in fluid. The discrete element method(DEM) technique is coupled with the lattice Boltzmann method(LBM), for fluid-grain interactions, to understand the evolution of submerged granular flows. The fluid phase is simulated using multiple-relaxation-time LBM(LBM-MRT) for numerical stability. In order to simulate interconnected pore space in 2-D, a reduction in the radius of the grains(hydrodynamic radius) is assumed during LBM computations. The collapse of granular column in fluid is compared with the dry cases to understand the effect of fluid on the runout behaviour. A parametric analysis is performed to assess the influence of the granular characteristics(initial packing) on the evolution of flow and run-out distances for slope angles of 0 °, 2.5°, 5 ° and 7.5 °. The granular flow dynamics is investigated by analysing the effect of hydroplaning, water entrainment and viscous drag on the granular mass. The mechanism of energy dissipation, shape of the flow front, water entrainment and evolution of packing density is used to explain the difference in the flow characteristics of loose and dense granular column collapse in fluid.展开更多
文摘在各类工程中产生了大量的高含水率废弃泥浆,过滤分离技术逐渐应用于泥浆的快速减量化中。为明确泥浆过滤的微观过程及堵塞机理,建立并验证了利用格子玻尔兹曼方法-离散单元法(Lattice Boltzmann method-discrete element method,LBM-DEM)模拟泥浆过滤。采用LBM-DEM方法模拟了多类条件下泥浆的过滤,包括不同泥浆含水率、过滤介质孔径、过滤压力及絮团性质。实验结果表明:泥浆在过滤过程中,过滤介质先作为主要的过滤单元,颗粒(或絮团)不断堵塞在过滤介质中或发生流失,当过滤介质完全堵塞后,颗粒(或絮团)不再发生流失,逐渐堆积在过滤介质表面,随着过滤的进行,泥皮逐渐累积增厚;堵塞完成的过滤介质及不断增厚的泥皮的组合体成为新的过滤系统。泥皮的渗透系数决定了新过滤系统的渗透能力,是影响泥浆过滤脱水的主要因素。LBM-DEM新方法的建立为研究及优化泥浆过滤效率提供了借鉴以及新的思路。
基金the Cambridge Commonwealth, Overseas Trust and the ShellCambridge-Brazil collaboration for the financial support to pursue this research
文摘This paper investigates the effect of initial volume fraction on the runout characteristics of collapse of granular columns on slopes in fluid. 2-D sub-grain scale numerical simulations are performed to understand the flow dynamics of granular collapse in fluid. The discrete element method(DEM) technique is coupled with the lattice Boltzmann method(LBM), for fluid-grain interactions, to understand the evolution of submerged granular flows. The fluid phase is simulated using multiple-relaxation-time LBM(LBM-MRT) for numerical stability. In order to simulate interconnected pore space in 2-D, a reduction in the radius of the grains(hydrodynamic radius) is assumed during LBM computations. The collapse of granular column in fluid is compared with the dry cases to understand the effect of fluid on the runout behaviour. A parametric analysis is performed to assess the influence of the granular characteristics(initial packing) on the evolution of flow and run-out distances for slope angles of 0 °, 2.5°, 5 ° and 7.5 °. The granular flow dynamics is investigated by analysing the effect of hydroplaning, water entrainment and viscous drag on the granular mass. The mechanism of energy dissipation, shape of the flow front, water entrainment and evolution of packing density is used to explain the difference in the flow characteristics of loose and dense granular column collapse in fluid.
