Flexible kirigami sheets in uniform and disturbed fluid flow

这项研究将研究放置在流体中的kirigami薄片的行为。近年来，由于简单的二维Kirigami图案薄片在受力时可以呈现出复杂的三维形状，对Kirigami应用的研究在广泛的研究领域中急剧增加。尽管现有关于kirigami模式的重要文献，但它们在流体力学中的应用一直非常有限。在这项工作中，研究了放置在流体中的kirigami薄片的行为。这个项目的更广泛的影响扩展到能够设计和部署具有所需几何形状、所需尾迹和所需任务的kirigami薄片。这种能力将在流动混合、流动控制和水下软机器人方面实现多种应用。这项研究的结果将通过将拟议的研究整合到针对K-12学生的外展计划中，并将这项研究纳入课堂，在不同的层面上传播。根据这项工作的成果，将设计和建造一个厨房展览，为普通观众呈现看不见的科学现象，并激发年轻一代对流体力学研究的浓厚兴趣。放置在流体流动中的Kirigami薄片构成不同尺度的流体-结构相互作用(FSI)：切割尺度和薄片尺度。这项工作的初步结果显示，当放置在流动中时，kirigami薄片呈现出各种三维形状的样本。这些结果表明，流动中的Kirigami薄板可以由于屈曲或极限环振荡而经历静态或动态流致不稳定性。这个项目首先关注于研究先前设计的放置在流中的kirigami模式的行为。然后，该项目专注于为流体特定的应用设计新的kirigami模式，并研究它们在均匀和扰动流动中的行为。这项工作的目标将通过进行几个系列的实验来实现，在这些实验中，将Kirigami图案的薄片放置在流体中。它们的位移将使用高速摄像机进行跟踪，由此产生的尾迹将使用气泡图像测速仪(BIV)进行量化。该项目的结果将通过为社区中的其他人存档三维形状和唤醒来潜在地影响诸如流量控制和FSI等领域。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.