Numeric Computing: A High-Order Kinetic-Based Quadrature Moment Method for Gas-Particle Flows

摘要本研究涉及开发和演示一种基于物理的气体颗粒流动预测工具。涉及气粒流动的物理现象在工程中普遍存在。喷雾燃烧、污染物运输、直升机熄火就是这样的例子。在工程设计中，对气体颗粒流动的理解和预测对于提高性能（如提高燃烧效率）或减轻有害影响（如直升机停电）至关重要。该项目的主要目标是开发一种工具，该工具可以应用于广泛的气体颗粒流，并且足够快速和准确，以影响设计过程。在这项工作中开发的预测计算模型将直接应用于汽车和飞机发动机、化学加工厂、火箭发动机、柴油和火花点火发动机以及工业炉的设计。气相多相流中常用的几种方法有拉格朗日法、流体体积法和水平集法。虽然它们都在一些应用中取得了成功，但它们也有一些根本性的弱点。在这个项目中，研究人员应用最近发展的直接正交矩法来处理欧拉框架中的动力学方程。由于不需要像拉格朗日方法那样跟踪和解析每个单独的粒子，DQMOM方法要快几个数量级。此外，采用基于非结构化网格的高阶谱差方法对控制方程进行离散化处理，在复杂构型下获得了比现有二阶方法更高的分辨率、精度和效率。开发的工具通过几个基准测试问题进行了验证。

High Order Kinetic-Based Quadrature Moment Method for Gas Particle Flows AbstractThis research involves developing and demonstrating a physics-based predictive tool for gas particle flows. Physical phenomena involving gas particle flows are ubiquitous in engineering. Spray combustion, pollutant transport, helicopter brownout are a few such examples. The understanding and prediction of gas particle flows are critical in engineering design to enhance performance (e.g. improved combustion efficiency) or mitigate harmful effects (e.g. helicopter brownout). The primary objective of this project is to develop a tool, which can be applied to a wide range of gas particle flows, and is fast and accurate enough to impact the design process. Predictive computational models developed in this work will have direct applications in the design of automotive and aircraft engines, chemical processing plants, rocket engines, diesel and spark ignition engines, and industrial furnaces. Several methods are popular in gas particle multiphase flows, for example, the Lagrangian method, the volume of fluid method and the level set method. Although they all achieved success in some applications, they also possess some fundamental weaknesses. In this project, the investigators apply the recently developed direct quadrature method of moments to treat the kinetic equation in an Eulerian framework. Since it is not necessary to follow and resolve each individual particle, as in the Lagrangian method, the DQMOM method is several orders faster. In addition, an unstructured grid based high-order spectral difference method is employed to discretise the governing equations to achieve higher resolution, and better accuracy and efficiency for complex configurations than the current state-of-the-art second-order methods. The developed tool is validated with several benchmark test problems.