Collaborative Research: The Roles of Inter-limb Jets and Body Angles in Metachronal Paddling

商用水下无人机通常依赖于单一的螺旋桨元件。如果这个部件发生故障，那么无人机就会丢失。相比之下，多个推进元件的存在将允许在单个螺旋桨发生故障时继续使用。天然水生生物提供了一个独特的机会，可以使用多种推进元件来产生小型喷气式飞机。磷虾、虾和小龙虾都使用几对高度协调的肢体来游泳。这种动物的四肢以低速从尾巴到头部有节奏地摆动，每一对的时间都比相邻的延迟。自然？S的设计比我们设计的水下无人机耗能少得多。机械元件，如齿轮和同步皮带，可以用来经济有效地模仿自然-S的设计。然而，这种超音速(顺序)划桨的基本流体动力学还没有被很好地理解。有限数量的研究表明，肢体形态、划桨顺序的精确计时以及生物体后喷流的产生都有助于这种独特的推进机制。这项研究项目考察了相邻肢体的协调如何与流经身体的水流相互作用，以在尾流中产生推进喷流。揭示超时划桨的潜在流体动力学原理将使工程设备具有可扩展性，从而能够高效地设计微型、受生物启发的自主水下无人机。这项研究项目考察了多个摆动桨的协调运动如何与绕过水下物体的大范围水流合并而产生推进力。将使用活体动物和机器人模型进行实验的组合。自由游动水生生物的层析粒子图像速度测量将用于验证物理模型预测的流场。自行式超时游泳机器人将被用来检查机器人的个人和集体运动的流动。关于身体角度、游泳速度和相邻距离的机械性能将在单个和小群的超棱角划桨机器人中被检验。一个主要的项目成果将是水生生物通过以低速度划动单个肢体来实现高身体速度的流体动力学机制。这项研究的结果将使工程师能够在工程设备上设计和协调多个螺旋桨的运动。此外，该研究项目还培养本科生和研究生进行生物工程的跨学科研究。这两个机构(NSF资助的俄克拉荷马州路易斯-斯托克斯少数族裔参与联盟和佐治亚理工学院焦点计划)的现有机制正被用来为该项目招募代表人数不足的学生，研究人员正在参与面向高中生及其教师的外联活动。

Commercial underwater drones typically rely on a single propeller element. If this element were to fail, then the drone would be lost. In contrast, the existence of multiple propulsion elements would permit continued use upon failure of a single propeller. Natural aquatic organisms illustrate a unique opportunity to use multiple propulsion elements to generate small-scale jets. Krill, shrimp, and crayfish, all use several pairs of limbs in highly coordinated motion to swim. The animal rhythmically oscillates its limbs from the tail-to-head at low velocity, with the timing of each pair delayed relative to its neighbors. Nature?s design uses much less energy than our engineered underwater drones. Mechanical elements, such as gears and timing belts, could be used to cost effectively mimic nature?s design. However, the underlying fluid dynamics of this metachronal (sequential) paddling is not well-understood. A limited number of studies have suggested limb morphology, the precision timing of the paddling sequence, and the generation of jets in the wake of the organism all contribute to this unique propulsion mechanism. This research project examines how coordination of adjacent limbs interact with the flow past the body to generate propulsive jets in the wake. Uncovering the underlying fluid dynamic principles of metachronal paddling will enable scalability to engineered devices, allowing for efficient design of miniaturized, bio-inspired autonomous underwater drones. This research project examines how the coordinated motion of multiple oscillating paddles merge with large-scale flow past a submerged object to generate propulsive forces. A combination of experiments with both live animals and robotic models will be used. Tomographic particle image velocimetry measurements of free-swimming aquatic organisms will be used to validate flow fields predicted by physical models. Self-propelled metachronal swimming robots will be used to examine the flow for individual and collective motion of the robots. Mechanical performance with respect to body angles, swimming speeds, and neighbor distances in individual and small groups of metachronal paddling robots will be examined. A primary project outcome will be the fluid dynamics mechanism by which aquatic organisms achieve large body speeds by paddling individual limbs at low velocity. The outcomes of this research will enable engineers to design and coordinate the motion of multiple propellers on engineered devices. In addition, the research project trains undergraduate and graduate students to conduct interdisciplinary research in bioengineering. Existing mechanisms at both institutions (NSF-funded Oklahoma Louis-Stokes Alliance for Minority Participation and Georgia Tech FOCUS program) are being used to recruit under-represented students for the project, and the researchers are participating in outreach activities to high school students and their teachers.