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

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

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.