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

0754493/0754922 Dabiri和Freund这个项目将结合新的实验和计算工具来设计和优化生物启发的推进器。工程技术要成功地复制生物系统的观测性能，需要了解推进器柔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，PIS将研究水母的游动，将其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的最简单的例子之一，但却表现出流固耦合、大变形和非线性弹性。此外，最近汇编的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。项目目标是通过最近开发的全耦合、二维、大变形、流体结构的解算器来实现的，该解算器在一种新的范例中发挥作用：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位形。实验工具将为数值模型的验证和改进提供必要的新数据，为设计优化提供初始输入，并评估最优解。数字粒子图像测速仪(DPIV)将在自由游动的水母形成的流场的多个平面上同时和顺序地采集测量数据。这些数据将使用传统的速度和涡度度量以及使用动力系统的新拉格朗日工具进行评估。这种合作将使实验和模拟的联合设计能够最大限度地提高它们对理解生物推进和优化以生物为灵感的工程设计的共同效用。加州理工学院最近开发了一门关于“生物推进”的课程，由其中一名PI教授，将作为这项研究的教育渠道。为了接触到更广泛的受众，伊利诺伊州小组将建立一个用户友好的开发代码版本，用于教学。这位加州理工大学的调查员还将继续担任加州理工大学新生暑期学院(FSI)研究项目的协调员，该项目将向未被充分代表的新生介绍研究型大学的环境。最后，两位PI都将在日常研究活动中指导本科生和研究生。

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.