Spatiotemporal Chaos and Particle Dynamics in Complex Flows

复杂流动中的时空混沌和粒子动力学

• 批准号: 0803153
• 负责人: Jerry Gollub
• 金额: $ 36万
• 依托单位: Haverford College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0803153&HistoricalAwards=false
• 关键词: Spatiotemporal; Chaos; Particle; Dynamics; Complex

****NON-TECHNICAL ABSTRACT****The accepted methods of studying fluid flows rely on tracking suspended particles, which are assumed to follow the motion of the fluid. However, in some cases this assumption may fail, casting doubt on the reliability of such measurements. Hence, it is important to achieve a better understanding of the motion of particles in fluid flows. The project, at a predominately undergraduate institution, will focus on the role of the inertia of particles in causing deviations from ideal particle motion, and potentially provides a way to improve fluid dynamical measurement methods. In related work, the project will use tracked particles to investigate the transition from regular fluid flow to the state of chaotic flow, where the flow becomes unpredictable. Such flows are widespread, and test our understanding of complex states. The novel method to be employed in the project involves the characterization of complex flow patterns by locating unique features of the flow pattern, such as the centers of local rotation, or vortices. The experiments will be conducted by pairing a postdoctoral trainee with undergraduate students. This approach provides important training advantages for both. ****TECHNICAL ABSTRACT****The motion of particles in fluids is important both as a fundamental topic in materials science, and because it provides a powerful diagnostic method of studying fluid flow. This project at a predominately undergraduate institution, will explore the theme of particle dynamics in fluids by means of small-scale well-controlled laboratory experiments. The motion of particles of varying sizes in flows at modest Reynolds number is investigated, to understand how the particles? behavior changes as their inertia increases. An important result will be to understand the conditions under which transported particles can serve as passive flow tracers, as is assumed for nearly every modern flow measurement technique. The behavior of a floating sheared layer of particles will be studied to gain insight into the deformation of soft materials, and particles flowing in a micro-channel will allow study of the transition to irreversible flow. Finally, the project will investigate the transition to space-time chaos by determining the curvature of particle trajectories. This novel method allows the special topological features of a complex fluid flow to be determined, and to be tracked over time as the flow makes a transition from regular flow to the state of space-time chaos. The pairing of a postdoctoral trainee with undergraduate students in this research provides important training advantages for both.

* 非技术摘要 * 研究流体流动的公认方法依赖于跟踪悬浮颗粒，这些悬浮颗粒被假定为跟随流体的运动。 然而，在某些情况下，这一假设可能会失败，使人们对这种测量的可靠性产生怀疑。 因此，更好地理解流体流动中颗粒的运动是很重要的。 该项目在一个主要的本科院校进行，将重点关注粒子惯性在导致偏离理想粒子运动中的作用，并可能提供一种改进流体动力学测量方法的方法。 在相关工作中，该项目将使用跟踪粒子来研究从规则流体流动到混沌流动状态的过渡，在混沌流动状态下，流动变得不可预测。 这种流动是普遍存在的，并且考验着我们对复杂状态的理解。 该项目采用的新方法涉及通过定位流型的独特特征（如局部旋转中心或涡流）来表征复杂流型。 实验将通过博士后实习生与本科生配对进行。 这种方法为双方提供了重要的培训优势。* 技术摘要 * 流体中粒子的运动是重要的，这既是材料科学的基础课题，也是因为它提供了研究流体流动的强大诊断方法。 这个项目在一个主要的本科院校，将探讨通过小规模的控制良好的实验室实验的流体中的粒子动力学的主题。 不同尺寸的颗粒在适当的雷诺数流动的运动进行了研究，了解如何颗粒？行为随着惯性的增加而改变。 一个重要的结果将是了解的条件下，传输的颗粒可以作为被动的流量示踪剂，是假设几乎每一个现代流量测量技术。 将研究颗粒的浮动剪切层的行为，以深入了解软材料的变形，并且在微通道中流动的颗粒将允许研究向不可逆流动的转变。 最后，该项目将通过确定粒子轨迹的曲率来研究向时空混沌的过渡。这种新的方法允许特殊的拓扑特征的复杂的流体流被确定，并随着时间的推移进行跟踪的流动，使从正常的流动的时空混沌状态的过渡。 在这项研究中，博士后实习生与本科生的配对为双方提供了重要的培训优势。