CAREER: Enabling Methods for Modeling and Control of Transitional and Turbulent Wall-Bounded Shear Flows

该方案为过渡和湍流壁面剪切流的模拟和控制引入了新的方法。这项拟议工作的一个重要属性是，它建立在最近的研究基础上，这些研究表明了渠道、管道和边界层中不确定因素的重要性，如自由流动湍流和壁面粗糙度。通过无传感器机制减阻是一项很有前途的技术，因为它代表了一种比壁挂式传感器和执行器阵列反馈流量控制简单得多的替代方案。虽然一些数值和实验研究表明，适当设计的无传感器策略可以显著减少阻力，但充分利用这些方法的一个障碍是缺乏设计和优化的理论框架。这种分析工具的缺乏极大地阻碍了无传感器方案的综合及其在不同流型中的推广。PI将为无传感器流量控制策略的设计和优化开发一种系统理论范例。新的范例是对众所周知的振动控制原理的时空模拟，在该原理中，通过在系统的系数中引入零均值振动来改变系统的动力学属性。PI的理论发现将使更有效的减阻策略成为可能，并为各种基于表面的驱动技术的设计提供指导。由于分布式系统在现代技术中变得无处不在，本提案的教育目标是使分布式概念在本科生和早期研究生水平上更加普遍。PI将推出一门新的入门课程，重点介绍以结构特性、实际应用和物理解释为特征的系统课程。与明尼苏达州科学博物馆合作，PI将组织关于自然界中流量控制策略多样性的受欢迎的讲座。将使用几个视频演示来说明来自自然界的观察如何激励研究、工程设计和技术开发。PI的目标是让高中生尽早接触到控制工程在将自然飞行和游泳运动员的效率带到人造系统中的核心作用。流动建模和控制是系统和控制理论中一个很有前途的活跃研究领域。操纵和控制流体流动的能力在许多应用中都是至关重要的，包括管道运输、空气和水中飞行器的减阻以及化学反应器和内燃机中的混合增强。成功的流量控制策略的潜在好处是巨大的；它们的范围从节省燃料的经济收益到涉及流体流动的工程系统的改善性能。由于表面摩擦阻力直接转化为飞机、舰船和潜艇的大量燃料消耗，因此迫切需要开发和利用这项工作中提出的先进理论和计算技术。

This proposal introduces new methods for modeling and control of transitional and turbulent wall-bounded shear flows. An important attribute of the proposed work is that it builds upon recent research manifesting the significance of uncertainty, such as free-stream turbulence and wall roughness, in channels, pipes, and boundary layers. Drag reduction by sensorless mechanisms is a promising technology, as it represents a much simpler alternative to feedback flow control with wall-mounted arrays of sensors and actuators. Although several numerical and experimental studies indicate that properly designed sensorless strategies yield significant drag reduction, an obstacle to fully utilizing these approaches is the absence of a theoretical framework for their design and optimization. This lack of analytical tools greatly impedes the synthesis of sensorless schemes as well as their extension to different flow regimes. The PI will develop a system-theoretic paradigm for design and optimization of sensorless flow control strategies. The new paradigm is a spatio-temporal analog of the well-known principle of vibrational control, where the system's dynamical properties are altered by introducing zero-mean vibrations into the system's coefficients. The PI's theoretical findings will enable more efficient drag reduction strategies and provide guidelines for design of various surface-based actuation techniques. Since distributed systems are becoming ubiquitous in modern technology, the educational goal of this proposal is to make distributed concepts more pervasive at the undergraduate and early graduate level. The PI will launch a new introductory course that will emphasize classes of systems characterized by their structural properties, practical applications, and physical interpretations. In collaboration with the Science Museum of Minnesota, the PI will organize popular lectures on diversity of flow control strategies in nature. Several video demonstrations will be used to illustrate how observations from the natural world motivate research, engineering design, and technology development. The PI's goal is to provide high-school students with an early exposure to the central role of control engineering in bringing the efficiency of natural fliers and swimmers to man-made systems. Flow modeling and control is a promising active research area in systems and control theory. The ability to manipulate and control fluid flows is of paramount importance in many applications including transport in pipes, drag reduction for air and water vehicles, and mixing enhancement in chemical reactors and combustion engines. The potential benefits of successful flow control strategies are enormous; they range from economic gains in fuel savings to improved performance of engineering systems involving fluid flows. Since skin-friction drag directly translates into large fuel consumption for airplanes, ships, and submarines, there is a critical demand for development and utilization of advanced theoretical and computational techniques proposed in this work.