EAPSI: Wake Induced by a Group of Seal Whiskers: Implication to High-sensitivity Underwater Flow Sensors

高灵敏度的水下流量传感器对于自主水下航行器(AUV)在黑暗、狭窄和不稳定的地形中导航至关重要，在这些地形中，基于视觉的传感器和声纳传感器无法很好地工作。海豹被发现能够追踪猎物，只需用它们的胡须就能捕捉到环境水中哪怕是微小的扰动。这归因于密封须在尾流中具有抑制涡激振动的特殊能力。该项目将在韩国浦项科技大学(POSTECH)进行海豹须流动实验，由Sang Joon Lee教授指导。合作提供流动设施和设备，以获得独特的数据，使人们能够对多个海豹胡须的尾流结构及其对设计高灵敏度水下流量传感器的影响有新的见解。许多研究者用理想化的晶须模型研究了晶须形态的关键参数对尾迹结构的影响。然而，由于海豹须的长度、大小和扭曲沿长度的自然变化，真正的海豹须如何改变尾流，特别是涡流脱落，还不是很清楚。具有特定构型的一组晶须如何相互作用以影响尾迹特性也不清楚。缺乏对一组多个海豹胡须产生的尾流结构的了解，阻碍了设计以胡须为灵感的高灵敏度水下流量传感器的能力。这项研究的目的是为了了解在雷诺数类似于港海豹须所受影响的情况下，多种不同构型的海豹须的尾迹。实验将在水洞中使用粒子成像测速仪(PIV)进行。这些结果将提供关于单个尾迹如何相互作用以及这种相互作用是否有利于抑制涡旋脱落的见解。这项研究将填补了解多个真正的海豹胡须创造的尾流结构的空白。最终，这些知识将被用于为在复杂环境中运行的AUV开发高灵敏度的水下流量传感器。该奖项由东亚和太平洋夏季学院计划资助一名美国研究生的夏季研究，由NSF和韩国国家研究基金会联合资助。

High-sensitivity underwater flow sensors are critical for autonomous underwater vehicles (AUVs) to navigate through dark, cramped, and unstable terrain where vision-based and sonar sensors do not function well. Harbor seals are found to be able to track their prey by capturing even minute disturbance of the ambient water solely by using their whiskers. This is attributed to the exceptional capability of seal whiskers to suppress vortex-induced vibration in the wake flow. This project will conduct flow experiments of seal whiskers at Pohang University of Science and Technology University (POSTECH) in South Korea, under the mentorship of Professor Sang Joon Lee. The collaboration provides flow facilities and equipment to obtain unique data that will enable new insights into the wake structure of multiple seal whiskers and its implication to design high-sensitivity underwater flow sensors. Many researchers have studied the effects of key parameters of the whisker morphology on wake structure with idealized whisker-like models. However, due to the natural variation in length, size and twist along the length of seal whiskers, it is not well understood how a real seal whisker changes wake flow, in particular the vortex shedding. It is also unclear how a group of whiskers with a certain configuration interact with each other to affect the wake properties. Lack of knowledge of the wake structure generated by multiple seal whiskers in a group hinders the capability to design whisker-inspired high-sensitivity underwater flow sensors. The goal of this research is to understand the wake of multiple seal whiskers of various configurations at the Reynolds number similar to which harbor seal whiskers are subject to. Experiments will be conducted in a water tunnel using Particle Imaging Velocimetry (PIV). The results will provide insights of how individual wakes interact with each other and if the interaction is beneficial to suppress the vortex shedding. This research will fill the gap of understanding the wake structure that multiple real seal whiskers create. Ultimately knowledge will be used to develop high-sensitivity underwater flow sensors for AUVs operating in a complex environment.This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the National Research Foundation of Korea.