Hydrodynamic Interactions in Vortex Dominated Flows in the Vicinity of Walls

到2050年，世界人口预计将达到100亿，这预示着一个资源日益紧张的时代，包括养活世界的蛋白质。与传统的牲畜相比，养殖鱼类所需的资源要少得多，是一种可行的蛋白质选择，可以从野外或人工养殖中收获，这一过程被称为水产养殖。截至2019年，加拿大水产养殖产值每年超过12亿美元，从业人员超过1万人，预计未来还会增长。随着这一产业的发展，了解鱼类对导航、喂养和社会互动的共同反应的刺激之间的相互关系变得至关重要，从而开发出更有效、更人道的做法和设施。拟议研究计划的长期目标是开发潜水致动器，通过策略性地操纵局部流动环境，在游动的鱼类中引起所需的行为反应。为此，五年研究计划沿着两个主题进行，第一个主题侧重于合成射流致动器的推力增强，第二个主题侧重于建模模型游泳者之间的流体动力学相互作用。主题1希望利用最近发现的“涡流喷嘴”效应，其中涡流环的冲量（动量）可以通过适当大小的孔径被动增强。假设旋涡喷嘴可以在不增加功率输入的情况下增强合成射流（从孔板喷射出的一系列旋涡环）的推力。因此，我们的目标是探索提高合成射流执行器效率的可能性，以便将来将其纳入工程水产养殖系统。主题2以最近的努力为基础，将游动的鱼建模为涡旋偶极子，以探索动物与其环境之间的相互作用。这些模型已被用于考虑动物成对游泳构型的稳定性，并揭示了一种纯粹的流体动力学机制，通过这种机制，一条流道中的一条鱼可以定向向上游游（称为流变性）。本主题的初步重点是利用通道中波动箔的原则数值模拟来验证旋涡偶极子模型，然后利用模拟来纳入旋涡尾迹的影响，这是当前模型中明显缺失的特征。将探讨涡旋尾迹对动物对稳定游动构型、通道中单个鱼的流变性以及通道中多个鱼的游动行为的影响。通过该项目培训的学生将掌握一套独特的、互补的工程和生物学技能，为他们加入从水产养殖到健康科学再到国防等一系列重要的加拿大行业做好准备。

The world population is expected to reach 10 billion by 2050, heralding an era of increasingly strained resources, including protein to feed the world. Fish, which require far fewer resources to grow than traditional livestock, are a viable protein option that can be harvested from the wild or farmed, a process referred to as aquaculture. As of 2019, the total value of production of aquaculture in Canada is over $1.2B annually and the industry employs over 10,000 people, with growth expected in the future. As this industry expands it becomes critically important to understand the interrelation of stimuli to which fish collectively respond for navigation, feeding, and social interaction to develop more efficient and humane practices and facilities. The long-term goal of the proposed research program is to develop submersible actuators than elicit desired behavioural responses in swimming fish by strategically manipulating the local flow environment. To this end, the five-year research plan proceeds along two themes, with the first focused on thrust enhancement of synthetic jet actuators, and the second on modeling hydrodynamic interactions between model swimmers. Theme 1 looks to exploit the recently discovered "vortex nozzle" effect, wherein the impulse (momentum) of a vortex ring can be passively enhanced by passing it through an appropriately sized aperture. It is hypothesized that the vortex nozzle can be used to enhance the thrust of a synthetic jet (a train of vortex rings ejected from an orifice) without any increase in power input. Thus, we aim to explore the possibility of improving synthetic jet actuator efficiency for future incorporation into engineered aquaculture systems. Theme 2 builds upon recent efforts to model swimming fish as vortex dipoles to explore interactions between animals and their environment. These models have been used to consider the stability of swimming configurations for animal pairs, and to uncover a purely hydrodynamic mechanism by which a single fish in a flow channel can orient itself to swim upstream (called rheotaxis). The preliminary focus of this theme is validating the vortex dipole model using principled numerical simulations of an undulating foil in a channel, then using the simulations to incorporate the effects of a vortex wake, a feature conspicuously missing from current models. The impact of the vortex wake on stable swimming configurations for animal pairs, rheotaxis of a single fish in channel, and the behavior of multiple fish swimming in a flow channel will be explored. Students trained by this program will be armed with a set of unique and complementary skills in engineering and biology that prepares them to join a range of critical Canadian industries, from aquaculture to health science to national defense.