Flexible kirigami sheets in uniform and disturbed fluid flow

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

The research will investigate the behavior of kirigami sheets placed in fluid flow. Research into applications of kirigami, wherein patterns of cuts are made in a sheet of material, has increased dramatically across a wide range of research areas in recent years due to the complex three-dimensional shapes that simple two-dimensional kirigami patterned sheets can assume when forces are applied on them. Despite the significant existing literature on kirigami patterns, their use in fluid mechanics has been extremely limited. In this work, the behavior of kirigami sheets placed in fluid flow is investigated. The broader impacts of this project extend to being able to design and deploy kirigami sheets with desired geometries, desired wakes, and for desired tasks. This ability will enable several applications in flow mixing, flow control, and underwater soft robotics. The findings of this research will be disseminated at different levels by integrating the proposed research into the outreach programs for K-12 students and by incorporating this research into classes. A galley exhibition will be designed and built based on the results of this work to render the invisible scientific phenomena tangible for a lay audience, and to spark deep interest in fluid mechanics research for younger generations. A kirigami sheet placed in fluid flow constitutes fluid-structure interactions (FSI) at different scales: the cut-scale and the sheet-scale. The preliminary results of this work have shown samples of a variety of three-dimensional shapes that kirigami sheets assume when they are placed in flow. These results show that kirigami sheets in flow can undergo static or dynamic flow-induced instabilities as a result of buckling or limit cycle oscillations. This project first focuses on investigating the behavior of previously designed kirigami patterns placed in flow. Then the project focuses on designing new kirigami patterns for fluid-specific applications and studying their behavior in uniform and disturbed flows. The goals of this work will be achieved by conducting several series of experiments where kirigami-patterned sheets are placed in fluid flow. Their displacements will be tracked using high speed cameras, and the resulting wakes will be quantified using bubble image velocimetry (BIV). The results of this project will potentially impact areas such as flow control and FSI by archiving the three-dimensional shapes and wakes for others in the community. 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.