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个螺旋桨元件。如果这个元素失败了，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推进器失效时继续使用。 天然水生生物说明了一个独特的机会，使用多个推进元件，以产生小规模的射流。 磷虾、小虾和小龙虾都是用几对肢体高度协调地游动。这种动物有节奏地从尾部到头部以低速摆动四肢，每对肢体的摆动时间相对于相邻的肢体有所延迟。 自然？的设计比我们设计的水下无人机使用的能源少得多。机械元件，如齿轮和同步带，可以用来成本有效地模仿自然？的设计。 然而，这种异时（顺序）划桨的基本流体动力学还没有得到很好的理解。有限数量的研究表明，肢体形态，划水顺序的精确定时，以及生物体尾流中喷射的产生都有助于这种独特的推进机制。 这个研究项目探讨了如何协调相邻的肢体相互作用的流动通过身体产生推进射流在唤醒。揭示异时性划桨的基本流体动力学原理将使工程设备具有可扩展性，从而能够有效设计小型化、生物启发的自主水下无人机。本研究探讨多个振荡桨的协调运动如何与经过水下物体的大规模水流合并以产生推进力。 将使用活动物和机器人模型的实验组合。自由游动的水生生物体的层析粒子图像测速测量将用于验证物理模型预测的流场。自行式异时游泳机器人将被用来检查个人和集体运动的机器人流。机械性能方面的身体角度，游泳速度，和邻居的距离在个人和小组的异时划桨机器人将被检查。一个主要的项目成果将是流体动力学机制，水生生物实现大的身体速度，在低速划动个别肢体。这项研究的成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在生物工程领域进行跨学科研究。 这两个机构（NSF资助的俄克拉荷马州路易斯-斯托克斯少数民族参与联盟和格鲁吉亚技术焦点计划）的现有机制正在被用来为该项目招募代表性不足的学生，研究人员正在参与高中学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.