Suspension Dynamics with Inertia: Combined Discrete-Particle Simulation and Constitutive Modeling Investigations

0853720Morris本项目研究具有惯性的刚性粒子在粒子尺度上的悬浮流动。颗粒尺度上的惯性由基于剪切速率、颗粒半径和运动粘度的雷诺数来定义。显著的粒子尺度惯性意味着雷诺数大于1。对于小颗粒，这通常意味着宏观尺度上的更大惯性。因此，必须考虑多个尺度上的惯性行为。基于PI先前的模拟与实验验证和已建立的模拟，本研究的重点是有限雷诺数下颗粒流动的模拟，探索单个颗粒的运动以及颗粒的悬浮。这些模拟使用了PI在格子-玻尔兹曼技术中的最新发展，该技术在并行计算算法中实现。模拟了几种基本流动，包括周期性的简单剪切流动和管道中的压力驱动流动，所有这些都是在具有不同颗粒体积分数的有限雷诺数条件下进行的。以前已经观察到，通过管道的流动显示迁移导致某些位置的明显堆积。确定悬浮液的有效性质并对其整体流动进行建模对于这些混合物的工程应用至关重要。利用应力和水动力扩散系数的统计分析，建立了悬浮流的连续介质模型。模型预测将与来自模拟和实验的更复杂的流动进行比较。散装悬浮液的研究是广泛应用的基础，涉及油墨、涂料和水泥等材料以及许多自然产生的流动。通过发展可供理论家和模型师使用的离散粒子理解，以及直接从结果发展连续描述，这项研究在两个方面提供了指导和方向。悬架动力学是一个复杂的课题，涉及物理、数学和工程学，因此为博士和本科生提供了很好的训练基础。该项目旨在吸引世界上最多元化的研究型大学之一--纽约城市学院的研究生和本科生研究人员参与。通过与不同的大学、实验室和行业的合作，年轻的研究人员将接触到从生物医学诊断(细胞分选)到陶瓷前体和水泥的交付等学科。研究结果将有助于在入门课程中开发一个模块，利用流体力学效应在微流控装置中进行分类。

0853720MorrisThis project addresses flow of suspensions of rigid particles with inertia at the particle scale. Inertia on the particle scale is defined in terms of the Reynolds number based on shear rate, particle radius and kinematic viscosity. Significant particle-scale inertia implies Reynolds number greater than unity. For small particles, this usually implies larger inertia at the macroscopic scale. Consequently, inertial behavior on multiple scales must be considered. Based on the PI's prior simulations verified against experiment and established simulations, the focus of this study is on simulation of particle-laden flows at finite Reynolds numbers, exploring motions of individual particles as well as particle suspensions. The simulations use the PI's recent developments in the lattice-Boltzmann technique, implemented in a parallel computational algorithm. A number of basic flows will be simulated, including periodic simple shear and pressure-driven flow in conduits, all under a range of finite-Reynolds number conditions with varying particle volume fraction. Flow through conduits showing migrations leading to pronounced accumulation at certain locations have been previously observed. Determination of effective properties of suspensions and modeling of their bulk flow is essential to engineering application of these mixtures. Using statistical analysis of the stress and hydrodynamic diffusivity, a continuum model for suspension flow will be developed. Model predictions will be compared against more complex flows, both from simulations and from experiments. The investigation of bulk suspensions is basic to a wide range of applications involving such materials as inks, coatings and cement as well as many naturally occurring flows. By developing discrete-particle understanding which may be used by theorists and modelers, and developing a continuum description directly from the results, this investigation provides guidance and direction on two fronts. Suspension dynamics is a complex topic, involving physics, mathematics and engineering and thus provides excellent training ground for doctoral and undergraduate research students. The project is designed to involve graduate and undergraduate researchers at one of the most diverse research university settings in the world, the City College of New York. Through collaborations with different universities, laboratories, and industries, young researchers will gain exposure to disciplines from biomedical diagnostics (cell sorting) to the delivery of ceramic precursors and cement. The research results will aid in developing a module in an introductory course using hydrodynamic effects for sorting in microfluidic devices.