鱼类捕食或逃逸时快速起动的水动力学机理研究

The hydrodynamics and performance of fish fast-start swimming during feeding strike or escape response will be studied by using the experimental, numerical and analytical methods. C-starts and S-starts are two main types of fast-starts, which are important for most fish in escaping predators and for some fish in achieving prey capture. C and S starts have received a lot of attention, but there are few quantitatively investigations on the hydrodynamic forces and performance. The lack of physical models of fast manoeuvres may be the material cause. On the other hand, the problems ask for the real self-propelled computing method and suitable analytical method to decrypt the secret of interaction between the morphing fish body and the water. So, it is necessary to model the fast-starts during predator-prey encounters and test the performance of manoeuvres with traditional hydrodynamic methods. To reveal the mechanisms of fast-starts will help the bionic design, and provide the mechanical evidence to understand the fish behavior and evolution.

本项目旨在用实验、数值和分析手段对典型鱼类的C和S型起动进行水动力学机理研究，进而建立特定鱼种(斑马鱼和黑鱼)在发生"捕食者与被捕食者遭遇"时(仅考虑不同距离和相对方位)快速机动的简化数学物理模型，并考虑不同外形鱼体的性能差别，从而探索鱼体通过机动实现顺利捕食或成功逃逸的力学原理。当前对C型和S型起动的机动性能进行研究的工作还比较少见，对"捕食者与被捕食者遭遇"进行建模的研究仍未见到，对"变形-受力-整体运动"的机理还缺乏认识。因此，有必要从流体力学角度对鱼类捕食或逃逸中的快速机动进行建模分析。深入研究鱼类快速机动的力学原理不仅对仿生设计大有裨益，还有助于对生物行为与生物进化的理解。

本项目本项目旨在用实验、数值和分析手段对典型的斑马鱼C型和S型起动进行水动力学机理研究，进而建立斑马鱼在发生“捕食与逃逸”行为时快速机动的简化数学物理模型，从而探索鱼体通过机动实现顺利捕食或成功逃逸的力学原理。从研究方法的角度来看，本项目执行期间完成了几个方面的工作：完善了虚功率原理的表述及其可行的应用；建成了耦合变形体动力学方程和流体力学方程的计算平台，实现了自主推进的计算；把鱼体看作粘弹性梁，从而建立了”肌肉力学-鱼体-流体”一体化耦合计算的简化模型；搭建了测量斑马鱼机动运动的实验平台。从研究的具体内容来看，本项目通过实验测量了斑马鱼C-Start和C-Turn运动，以及捕食的S型起动等，并完整地分析了运动学和动力学特征；对C-Start和C-Turn进行了遗传算法的建模，并分析了其转弯的控制机制；通过一体化耦合计算，分析了鱼体巡游时的肌肉力学性能；对波状推进的推力形成机制进行了涡动力学分析，并研究了近地面效应。