Collaborative Research: MSPA-MCS: Simulation and Visualization of Flow at Interfaces

界面流动的模拟与可视化摘要流体动力学中的许多重要现象都涉及到两个流体区域之间边界的变化。这类流体现象包括两种流体流动的不稳定性、透明液体和含颗粒液体之间边界的演变以及空气和水之间边界的行为。这项研究使用计算机模拟来研究流体之间的这种界面，以及从这些模拟中创建图像的新方法，以便研究人员更好地了解流体行为。更好地模拟和可视化流动界面将促进科学理解和帮助工程设计。更广泛的影响领域包括设计用于医疗的自推进微型机器，河流表面运输污染分析和控制，以及控制喷墨打印机的液滴形成。该项目还通过培训学生、雇用少数族裔学生进行暑期实习、为研究社区开发可视化流体模拟课程以及在网络上分发代码和数据来推进教育。本研究从修改现有的几种不同类型界面流的数值模拟代码开始。在本研究中模拟和可视化的具体科学现象包括：颗粒负载区域沉降到透明流体中的不稳定性，包括瑞利-泰勒不稳定性的模拟；由于接触线上的表面张力效应，形成了流体辫状结构和其他结构；通过淡水/咸水界面落下的固体颗粒的内部飞溅；和运动简单的铰接图形和其他微纳米尺度的机构，通过粘性流体游泳。利用模拟数据，界面流动可视化的新方法针对每种现象量身定制，利用各种技术，包括颗粒表面创建、3D流动中临界点的识别和跟踪、流线放置和模拟流变流体悬浮液的各向异性照明。

Simulation and Visualization of Flow at InterfacesAbstractA wide variety of important phenomena in fluid dynamics involve the changes of the boundary between two fluid regions. Such fluid phenomena include the instabilities in two-fluid flows, the evolution of the boundary between clear and particle-laden liquids, and the behavior of the boundary between air and water. This research uses computer simulations to study such interfaces between fluids together with new methods of creating images from these simulations in order to allow researchers to gain a better understanding of the fluid behaviors. Better simulation and visualization of flow interfaces will advance scientific understanding and aid in engineering design. Areas of broader impact include the design of self-propelled micromachines for medicine, surface-transported pollution analysis and control on rivers, and controlling droplet formation for ink-jet printers. This project is also advancing education by training student, hiring minority students for summer internships, developing courses on visualizing fluid simulations for the research community, and distributing code and data on the web.This research begins with the modification of existing numerical simulation codes for several different classes of interfacial flows. The specific scientific phenomena that are simulated and visualized in this research includes: instabilities in the sedimentation of particle-laden regions into clear fluids, including the analogue of the Rayleigh-Taylor instability; the development of fluid braids and other structures due to surface tension effects at contact lines; the internal splashes of solid particles falling through fresh/salt-water interfaces; and locomotion of simple articulated figures and other micro- and nano-scale mechanisms for swimming through viscous fluid. Using the data from the simulations, new methods of visualizing the flow at interfaces are tailored to each phenomena utilizing various techniques including surface creation from particles, identification and tracking of critical points in 3D flows, streamline placement, and anisotropic lighting for simulated rheoscopic fluid suspensions.