仿生鱼集群游动特性和动力学机理研究

Collective swimming of fish contains complex mechanical principles and belongs to a frontier scientific subject in the fundamental research of interdisciplinary fields, e.g. biomechanics of animal locomotion and bionics. This project is to explore the schooling characteristics of bionic fish and the underlying dynamical mechanisms by means of combination of physical modeling and numerical simulation. The research work mainly includes the following aspects. First of all, an integrated modeling and corresponding numerical method of kinematic chain in fish swimming, i.e. muscle action-fish body deformation and overall motion-fluid response, are developed, and then a large-scale parallel computing platform for coupling the dynamics of fish body structures under muscle excitation and fluid mechanics is established. On this basis, numerical simulations of collective swimming of bionic fish are carried out to investigate the kinematics and dynamics of bionic fish schools with different population sizes and individual differences, including the formations of motion patterns, ordering and stability of configurations, propulsive performances and energy characteristics, etc. The underlying mechanisms of flow interaction and flow control, as well as the laws of input, transmission and dissipation of energy in the schools, are explored. Further, possible hydrodynamic advantages in school of fish are revealed, and rationality of Lighthill conjecture is tested. The results obtained may not only have important significance for understanding the fundamental principles of coordinated collective behaviours in biological systems, but also provide theoretical support for engineering applications such as design optimization and formation control of bionic underwater vehicles.

鱼类集群游动蕴含着复杂的力学原理，是运动生物力学和仿生学等交叉领域的前沿基础科学课题。本项目通过物理建模和数值计算相结合的研究方法，开展仿生鱼集群游动特性和动力学机理研究。主要内容包括：开展鱼游运动链中“肌肉激励-鱼体变形和整体运动-流体响应”过程的一体化建模和计算方法研究，建立耦合求解肌肉激励下的鱼体结构动力学与流体力学的大规模并行计算平台；在此基础上，开展仿生鱼集群游动的数值模拟，考察不同群体规模、个体差异等条件下鱼群游动的运动学和动力学特性，包括运动模式形成、结构有序性和稳定性、推进性能和能量特性等，探究鱼群游动中复杂的流动干扰和流动控制机制，以及鱼群系统的能量输入、传递和耗散规律，进而揭示鱼群游动中可能存在的水动力学优势,检验Lighthill猜想的合理性。研究结果不仅对认识生物集群运动的基本原理具有重要意义，也可为仿生潜航器的优化设计和编队控制等工程应用提供理论支撑。

本项目针对鱼类集群游动中的关键科学问题，建立了考虑鱼游运动链末端的“肌肉-鱼体-流体”互相作用过程的一体化模型和流固耦合数值模拟方法，开展了仿生鱼自由游动和多鱼集群游动、仿生拍动柔性板推-阻力和尾迹转捩特性及其标度律、仿生拍动柔性板大规模集群游动、仿生柔性体流动控制和多体干扰等四个方面的研究，探讨了仿生鱼和仿生拍动柔性板集群游动特性，揭示了多体流固耦合系统复杂的流动物理机理和流动控制机制，进一步探索了生物流体力学基本原理的潜在应用。依据项目研究计划，完成了研究内容，达到了预期研究目标。