Numerical investigation of passive and active flapping in fish propulsion

近年来，随着工程师和生物学家对水生生物在设计和运动性能上的显着多样性的关注，游泳流体动力学的研究引起了人们的极大关注。这类研究的一个重要困难是，活鱼如何实现比最新的机器鱼更高的推进效率和稳定性。这种困难阻碍了后者的实际应用。通过对高速水流中鱼的游动和薄壁结构的被动扑动的观察，提出了对被动扑动和主动扑动的基本认识，从而最终实现了高效的人工血管状游泳器。研究基于流动-结构相互作用的双向耦合和三维数值模拟。我们在Toal申请了为期6年的两个资助期。在第一个为期3年的资助期内，重点将是模型开发和大涡模拟，重点是大流动结构和被动和主动扑翼的基本贡献，以及它们对提高推进效率的相互作用。在第二个资助期，我们将重点研究与游泳稳定性相关的直接数值模拟和主动控制。此外，如果时间允许，我们将在第二个资助期内进行主动控制参数的优化，以实现最大的推进效率和游泳稳定性。这些控制参数可用于指导高效机器鱼的设计。

The study of swimming hydrodynamics has attracted considerable attention in recent years as engineers and biologists have focused on the remarkable diversity in design and locomotion performance of aquatic organisms. One important difficulty of such study is that how the live fishes achieve much higher propulsion efficiency and stability than that of the up-to-date robotic fishes. Such difficulty hinders the realization of the latter for practical applications. Based on the observations on fish swimming and passive flapping of thin structure in high speed flow, we propose to develop a fundamental understanding of the passive and active flapping, which leads to the eventual realization of high effective artificial carangiform swimmer. The research is based on two-way coupling of flow-structure interaction, and three-dimensional numerical simulations. We apply for two funding periods for 6 years in toal. During the first funding period of 3 years the emphasis will be model development and large eddy simulation, which focuses on the large flow structures and the essential contributions of passive and active flapping and their interplay for increasing propulsion efficiency. In the second funding period we will focus on direct numerical simulations and the active controls relevant to swimming stability. Furthermore, if time permits, we will perform in the second funding period the optimization of the active control parameters to achieve the maximum propulsion efficiency and swimming stability. Such control parameters can be used to direct the design of high effective robotic fish.