Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904, United States of America.
Bioinspir Biomim. 2024 Jan 23;19(2). doi: 10.1088/1748-3190/ad1b2e.
This study investigates the interaction of a two-manta-ray school using computational fluid dynamics simulations. The baseline case consists of two in-phase undulating three-dimensional manta models arranged in a stacked configuration. Various vertical stacked and streamwise staggered configurations are studied by altering the locations of the top manta in the upstream and downstream directions. Additionally, phase differences between the two mantas are considered. Simulations are conducted using an in-house developed incompressible flow solver with an immersed boundary method. The results reveal that the follower will significantly benefit from the upstroke vortices (UVs) and downstroke vortices depending on its streamwise separation. We find that placing the top manta 0.5 body length (BL) downstream of the bottom manta optimizes its utilization of UVs from the bottom manta, facilitating the formation of leading-edge vortices (LEVs) on the top manta's pectoral fins during the downstroke. This LEV strengthening mechanism, in turn, generates a forward suction force on the follower that results in a 72% higher cycle-averaged thrust than a solitary swimmer. This benefit harvested from UVs can be further improved by adjusting the phase of the top follower. By applying a phase difference ofπ/3to the top manta, the follower not only benefits from the UVs of the bottom manta but also leverages the auxiliary vortices during the upstroke, leading to stronger tip vortices and a more pronounced forward suction force. The newfound interaction observed in schooling studies offers significant insights that can aid in the development of robot formations inspired by manta rays.
本研究采用计算流体动力学模拟方法研究了双蝠鲼群体的相互作用。基础案例由两个相位一致的三维蝠鲼模型组成，它们以堆叠的方式排列。通过改变上游和下游顶部蝠鲼的位置，研究了各种垂直堆叠和流向交错的配置。此外，还考虑了两个蝠鲼之间的相位差。模拟使用自主开发的不可压缩流求解器和浸入边界法进行。结果表明，根据追随者的流向分离，它将从上行涡（UVs）和下行涡中显著受益。我们发现，将顶部蝠鲼放置在底部蝠鲼下游 0.5 个体长（BL）处，可优化其对底部蝠鲼 UVs 的利用，从而促进顶部蝠鲼胸鳍在下行时形成前缘涡（LEVs）。这种 LEV 强化机制反过来又会在追随者上产生向前的吸力，导致其周期平均推力比单独游泳者高 72%。通过调整顶部追随者的相位，可以进一步提高从 UVs 中获得的收益。通过对顶部蝠鲼施加π/3的相位差，追随者不仅受益于底部蝠鲼的 UVs，还利用了上行时的辅助涡，从而产生更强的翼尖涡和更明显的向前吸力。在群体研究中观察到的这种新相互作用提供了重要的见解，有助于开发受蝠鲼启发的机器人编队。
