Collaborative Research: Optimizing flexible swimmers -- from jellyfish to engineered propulsors

0754493/0754922 Dabiri 和 Freund 该项目将在仿生推进器的设计和优化中结合新的实验和计算工具。对于工程技术来说，要成功复制所观察到的生物系统性能，需要了解推进器灵活性和非线性弹性的动力学作用，这些特征在生物推进系统中普遍存在。为了实现这一目标，PI 将研究水母游泳作为一般生物推进的模型系统。这些动物是一个引人注目的模型，因为它们代表了生物推进器最简单的例子之一，并且表现出耦合的流体-结构相互作用、大变形和非线性弹性。此外，最近编制的包含 600 多种水母的形态数据库可用于将工程设计优化的结果与自然界中发现的解决方案进行比较。最近开发的全耦合、二维、大变形、流体结构求解器使该项目目标成为可能，该求解器在新颖的范式中运行：指定材料属性和驱动力，而不是推进器运动学或流入边界条件。数值方法最终将扩展到轴对称和三维构型。实验工具将为数值模型的验证和细化、设计优化的初始输入以及最佳解决方案的评估提供重要的新数据。数字粒子图像测速（DPIV）测量将在自由游动的水母产生的流场的多个平面中同时和顺序收集。这些数据将使用传统的速度和涡度指标以及动力系统中的新拉格朗日工具进行评估。此次合作将实现实验和模拟的共同设计，以最大限度地提高它们在理解生物推进和优化受生物启发的工程设计方面的相互效用。加州理工学院最近开发的一门“生物推进”课程，由一名 PI 教授，将作为这项研究的教育渠道。为了覆盖更广泛的受众，伊利诺伊州小组将建立一个用户友好版本的开发代码以供在教学中使用。这位加州理工学院的调查员还将继续担任加州理工学院新生暑期学院（FSI）研究项目的协调员，该项目向代表性不足的新生介绍研究型大学的环境。最后，两位 PI 都将指导本科生和研究生的日常研究活动。

0754493/0754922 Dabiri and Freund This project will combine new experimental and computational tools in the design and optimization of biologically-inspired propulsors. For engineering technology to successfully replicate the observed performance of biological systems requires understanding the dynamical role of propulsor flexibility and nonlinear elasticity, characteristics that are ubiquitous in biological propulsion systems. Toward this aim, the PIs will investigate jellyfish swimming as a model system for biological propulsion in general. These animals are a compelling model because they represent one of the simplest examples of a biological propulsor and yet exhibit coupled fluid-structure interactions, large deformations, and nonlinear elasticity. Furthermore, a recently compiled morphological database of over 600 species of jellyfish is available to compare the results of the engineering design optimization with the solutions found in nature. The project objectives are made possible by the recent development of a fully-coupled, two-dimensional, large-deformation, fluid-structure solver that functions within a novel paradigm: material properties and actuation forces are specified instead of propulsor kinematics or inflow boundary conditions. The numerical method will eventually be extended to axisymmetric and three-dimensional configurations. Experimental tools will provide essential new data for validation and refinement of the numerical model, initial inputs to the design optimization, and evaluation of the optimal solutions. Digital particle image velocimetry (DPIV) measurements will be collected both simultaneously and sequentially in multiple planes of the flow field created by free-swimming jellyfish. These data will be evaluated using traditional velocity and vorticity metrics as well as by using new Lagrangian tools from dynamical systems. The collaboration will enable co-design of the experiments and simulations to maximize their mutual utility for understanding biological propulsion and optimizing biologically-inspired engineering designs. A recently developed course on "Biological Propulsion" at Caltech, taught by one of the PIs, will serve as an educational outlet for this research. In order to reach a broader audience, the Illinois group will set up a user-friendly version of the developed code for use in instruction. The Caltech investigator will also continue in his role as Coordinator of the Freshmen Summer Institute (FSI) Research Program at Caltech, which introduces underrepresented incoming freshman to the environment of a research university. Finally, both PIs will mentor undergraduate and graduate students in the day-to-day research activities.