CAREER: Fluid-Structure Interactions of Ultrasoft Shape-Morphing Membranes

流体-结构相互作用是许多自然现象和技术环境的核心。然而，很少有研究已经解决了流体-结构相互作用，其中相互作用的结构是薄的，超软的（果冻状），并且其中流动是湍流的。由于这种薄的弹性材料（膜）可以经历大的、非线性的、流动诱导的形状变形，这一主题的复杂性增加了。因此，在我们对这种超软固体在湍流中的行为的理解方面存在知识差距。 该项目的主要目的是更深入地了解这种特殊的组合，其中非线性弹性和（非线性）流体动力学纠缠在一起，导致新的流动特性的出现。该研究将开发这类软材料用于流量控制，阻力调制和能量提取应用。该项目还将包括重要的教育活动，并促进流体动力学和材料科学领域的研究生和本科生研究人员之间的合作，以及组织研究生暑期学校和本科生暑期学校（新引进）在复杂的流动和软固体。这个项目的目标是发展一个全面的了解耦合流体-湍流与超软材料的结构化相互作用，这些超软材料容易发生大的流动诱导重构（通过拉伸变形促进）。这些可能发生在非线性材料特性和高度湍流联合收割机相结合的情况下，从而产生具有工程效益的流动特性，例如在流体动力学能量提取或高升力水下表面的开发中。水槽实验室实验将结合从理论建模和数值模拟中获得的见解，以解开电流体动力学相互作用。该提案的三个主要目标是：（i）使用三自由度平台在水槽设施中开发和系统地探索扑动薄膜水翼，（ii）研究弹性形状变形对非定常升力和流致共振现象的影响，以及（iii）了解薄膜振荡可以调节以控制湍流和调节阻力的机制。这种方法有望产生对湍流环境中超软材料力学的基本见解，并为潮汐和河流能源提取的未来创新提供机会。此外，通过促进研究生的教育互动和跨学科接触，以及通过公共宣传活动，预计会取得重大成果。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Fluid-structure interactions are central to many natural phenomena and in technological settings. However, very few studies have addressed the fluid-structure interactions where the interacting structure is thin, ultrasoft (Jell-O-like), and where the flow is turbulent. The complexity of this topic is increased by the fact that such thin elastic materials (membranes) can undergo large, nonlinear, flow-induced shape morphings. Hence, there is a knowledge gap in our understanding of the behavior of such ultrasoft solids in turbulent flows. The principal aim of this project is to develop a deeper understanding of this special combination where nonlinear elasticity and (nonlinear) fluid dynamics are entangled, leading to the emergence of new flow properties. The research will develop this class of soft materials for use in flow control, drag modulation, and energy extraction applications. The project will also encompass significant educational activities, and foster collaborations between graduate and undergraduate researchers in fluid dynamics and materials science areas, as well as the organization of a graduate summer school and an undergraduate summer school (newly introduced) on complex flows and soft solids.The goal of this project is to develop a comprehensive understanding of the coupled fluid-structure interactions of turbulent flows with ultrasoft materials that readily undergo large flow-induced reconfigurations (facilitated by stretching deformations). These can occur in a regime where nonlinear material properties and highly turbulent flows combine, giving rise to flow properties that are of engineering benefit, such as in hydrokinetic energy extraction or in the development of high-lift underwater surfaces. Laboratory experiments in a water flume will be combined with insights gained from theoretical modeling and numerical simulations to unravel the electrohydrodynamic interactions. The three broad aims of the proposal will be to (i) develop and systematically explore flapping membrane hydrofoils in a water flume facility using a three-degree-of-freedom platform, (ii) study the implications of elastic shape-morphing on unsteady lift and flow-induced resonance phenomena, and (iii) understand the mechanisms by which the membrane oscillations can be tuned to control turbulence and modulate drag. This approach is expected to yield fundamental insight into the mechanics of ultrasoft materials in turbulent flow environments and provide opportunities for future innovation in tidal and fluvial energy extraction. Additionally, significant outcomes are expected by enabling educational interactions and interdisciplinary exposure for graduate students, and through public outreach activities.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.