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。与传统家畜相比，鱼类需要的资源要少得多，是一种可行的蛋白质选择，可以从野外或养殖中收获，这一过程被称为水产养殖。截至2019年，加拿大水产养殖总产值每年超过12亿美元，该行业雇佣了超过1万名员工，预计未来还会增长。随着这一行业的发展，了解鱼类集体对航行、摄食和社会互动做出反应的刺激之间的相互关系变得至关重要，以发展更有效和更人性化的做法和设施。拟议研究计划的长期目标是开发潜水器执行器，通过战略性地操纵局部流动环境，在游动的鱼类中引发所需的行为反应。为此，五年研究计划沿着两个主题进行，第一个主题是合成喷气助推器的推力增强，第二个主题是对模型游泳运动员之间的水动力相互作用进行建模。主题1试图利用最近发现的“涡流喷嘴”效应，在这种效应中，涡环的冲量(动量)可以通过适当大小的孔径被动增强。假设涡流喷嘴可以在不增加功率的情况下增加合成射流(从小孔喷出的一串涡环)的推力。因此，我们的目标是探索提高合成射流致动器效率的可能性，以便将来应用到工程水产养殖系统中。主题2以最近的努力为基础，将游动的鱼模拟为涡旋偶极子，以探索动物与环境之间的相互作用。这些模型被用来研究动物对游动构型的稳定性，并揭示一种纯粹的水动力机制，通过这种机制，流道中的一条鱼可以将自己定位到上游游泳(称为流变性)。这一主题的初步重点是通过对通道中起伏的翼片进行原则性的数值模拟来验证涡偶极子模型，然后使用模拟来考虑涡旋尾迹的影响，这是当前模型中明显缺失的一个特征。本课程将探讨涡流尾迹对动物对稳定游动构型的影响，单个鱼在流道中的流变性，以及多条鱼在流道中游动的行为。通过该项目培训的学生将掌握一套独特的工程和生物互补技能，为他们进入加拿大一系列关键行业做好准备，从水产养殖到健康科学再到国防。

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.