CAREER: Interaction of Turbulence with Flexible Surfaces: Coherent Structures and Near-Wall Dynamics

该项目将研究柔性表面与湍流之间的相互作用。分析将基于计算流体动力学模拟和理论的结合。在许多实际情况下，表面在流体力的影响下会发生变形，例如飞机机翼的振动、人体血管和柔性涂层。这个项目的目标是发展新的理论，帮助解释这些相互作用将如何改变流的结构。在与大学教育办公室合作开展的针对女性和少数民族的外联活动中，将设计日常生活中流体-结构相互作用的简单演示。目前项目的重点是研究柔性表面与近壁湍流之间相互作用的机制。特别强调的是理解1)被动和主动壁面运动如何改变近壁面湍流循环，2)这些变化是否以及为什么会导致湍流减少，以及3)什么因素导致了相互作用模式的改变。将各向同性和各向异性壁面运动进行比较，探讨各向异性壁面运动对近壁面湍流循环影响的潜在差异。上述目标将通过结合流固耦合问题的高保真直接数值模拟（DNS）和一套分析工具（包括解析分析和线性随机估计方法）来实现。解决方案分析将提供某些流动和材料参数对实现所需相互作用模式可能性的影响的先验和后验估计。当前项目的教育目标是致力于吸引和留住工程领域的女性研究人员，通过当地的外展活动来实现，以及为互联网和iPhone应用程序开发针对小学和中学儿童的交互式流体流动可视化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The project will investigate the interactions between the flexible surfaces and turbulent flows. The analysis will be based on the combination of computational fluid dynamics simulations and theory. Surfaces that deform under the influence of fluid forces occur in many practical situations, such as vibrations of aircraft wings, human blood vessels, and compliant coatings. The goal of this project is to develop new theories that help explain how these interactions will change the structure of the flow. Simple demonstrations of the fluid-structure interactions in an everyday life will be designed for the outreach activities targeted to females and minorities conducted in collaboration with the university office of education. The focus of the current project is on investigation of the mechanisms involved with the interaction between the flexible surfaces and the near-wall turbulence. Particular emphasis is on understanding of 1) how passive and active wall motions alter the near-wall turbulence cycle, 2) whether and why these alterations lead to a turbulence reduction, and 3) what factors are responsible for changing the mode of interaction. A comparison between the isotropic and anisotropic wall motions will be made to investigate the potential differences of the influence of these motions on the near-wall turbulence cycle. The above goals will be accomplished via a combination of high-fidelity Direct Numerical Simulations (DNS) of a coupled fluid-structure interaction problem, and a suite of analysis tools, including a resolvent analysis, and a linear stochastic estimation approach. Resolvent analysis will provide a-priori and a-posteriori estimates of the effect of certain flow and material parameters on a likelihood of achieving a desired mode of interaction. The educational objectives of the current project are devoted to attraction and retention of female researchers to the field of engineering, accomplished via local outreach activities, as well as a development of interactive fluid flow visualizations for the Internet and iPhone applications, targeted to elementary and middle school children.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.