CAREER: Numerical Investigations of Biological and Bio-inspired Locomotion

摘要CBET-0645228J。他提出的程序解决了对高保真、计算效率高的工具的需求，用于模拟具有移动、变形表面的物体产生的流动。该工具将适用于广泛的生物学和技术方面的流体动力学问题，但在本计划期间，重点将致力于研究柔韧性在流体中生物形态运动中的作用。该研究计划包括两个平行的部分：(1)开发三维非定常流与柔性表面耦合的模拟工具；(2)在一系列生物激励的基准问题中对主动和被动灵活性进行数值研究。这项研究计划将解决几个关于运动的公开问题，教育部分有一个很容易让学生在许多层面上获得的范例。智力优势：许多有机体在液体中自我推进和机动的优雅和敏捷，很难与我们自己的模仿尝试相媲美。尽管进行了数千年的观察，但我们仍然缺乏对大多数形式的生物运动的基本物理学的足够了解，以构建具有类似功能的车辆。对这些问题的研究是通过实验、计算和理论分析的多学科串联最有效的，最近的兴趣导致了这些工具的新的和令人兴奋的进展。实验表明，高度非定常的涡流结构和表面灵活性在产生鱼和昆虫所需的推力、升力和操纵力方面起着关键作用。数值模拟发挥着强大而必要的作用，因为从自由移动的生物体中获得详细的流动测量显然是困难的。传统的流动解算器自然不适合于生物运动的大表面变形。为了绕过这些困难，充分发挥涡度的重要作用，本程序中的模拟将依赖于粘性涡旋质点方法，PI在这方面有丰富的经验。这种方法不使用固定的网格，而是使用自动适应不断演变的流动的计算粒子；因为只有在存在涡量的地方才需要粒子，所以该方法自然地将计算资源集中在空间紧凑的区域。该工具将被用来解决关于生物运动的几个公开问题，特别关注主动和被动灵活性在基本力学中的作用。一个关键的发展将是三个典型的“柔体运动”问题的构建和研究。这些问题都将通过一系列分层次的子问题来解决，这些子问题会逐渐提供更多的洞察力。这些研究的结果可用于后续的轨迹规划和降阶建模工作，最终目标是设计控制策略。更广泛的影响：这项研究计划的工具和结果将与受生物启发的水上和微型飞行器设计以及内部生物流动的其他重要问题相关。此外，结果将被提炼并整合到一个由三个主要部分组成的教育计划中：开发生物系统流体动力学的本科课程；通过加州大学洛杉矶分校工程和多样性卓越中心访问当地的K-12学校；以及开发和指导本科研究项目。这些组件中的每一个都将使用自然运动的范例来激发流体动力学和一般工程中的基本概念。对洛杉矶和英格尔伍德联合学区当地学校的访问将集中于吸引弱势群体和传统上代表不足的群体的学生进入科学和工程专业。PI和一小群本科生助理将通过问一些问题来让学生参与进来，比如：为什么飞机不像昆虫一样飞行？然后引导互动讨论和演示，鼓励广泛参与。

AbstractCBET-0645228J. Eldredge, UCLAThe proposed program addresses a need for a high-fidelity, computationally efficient tool for simulating flows produced by bodies with moving, deforming surfaces. This tool will be applicable to a wide range of fluid dynamical problems of biological and technological interest, but focus in this program period will be devoted to studying the role of flexibility in biomorphic locomotion in fluids. The proposed research program consists of two parallel components: (1) Development of a simulation tool for three-dimensional unsteady flow coupled with flexible surfaces, and (2) Numerical investigation of active and passive flexibility in a series of biologically-motivated benchmark problems. The research program will address several open questions of locomotion, and the educational component has a paradigm that is easily accessible to students at many levels.Intellectual merit: The grace and agility with which many organisms self-propel and maneuver in fluids is hardly matched by our own attempts of mimicry. We still lack sufficient understanding of the fundamental physics of most forms of biological locomotion to construct vehicles with similar functionality, despite thousands of years of observation. Investigation of these problems is most effective with a multidisciplinary tandem of experimental, computational and theoretical analysis, and recent interest has led to new and exciting advances with each of these tools. Experiments reveal that highly unsteady vortical flow structures and surface flexibility play critical roles in generating the requisite thrust, lift and maneuvering forces in fish and insects. Numerical simulations serve a powerful and necessary role due to the obvious difficulties in obtaining detailed flow measurements from freely-moving organisms. Conventional flow solvers are not naturally suited to the large surface deformations of biological locomotion. In order to circumvent these difficulties and to exploit the important role of vorticity, the simulations in this program will rely on the viscous vortex particle method, with which the PI has extensive experience. In lieu of a fixed grid, this method uses computational particles that automatically adapt to the evolving flow; because particles are only needed where vorticity is present, the method naturally focuses computational resources on a spatially compact region. The tool will be used to address several open questions regarding biological locomotion, with particular attention devoted to the roles of active and passive flexibility in the basic mechanics. A key development will be the construction and investigation of three canonical "flexible-body locomotion" problems. These problems will each be solved through a hierarchical series of sub-problems that give progressively more insight. The results of these studies can be used for later work in trajectory planning and reduced-order modeling, with the ultimate goal of devising control strategies. Broader impacts: The tools and results from this research program will be relevant to other important problems in bio-inspired aquatic and micro air vehicle design and internal biological flows. Furthermore, the results will be distilled and integrated into an educational program that consists of three principal components: development of an undergraduate course on the fluid dynamics of biological systems; visits to local K-12 schools through the UCLA Center for Excellence in Engineering and Diversity; and development and mentoring of undergraduate research projects. Each of these components will use the paradigm of natural locomotion to motivate fundamental concepts in fluid dynamics, and engineering in general. The visits to local schools in the Los Angeles and Inglewood Unified School Districts will focus on drawing students from disadvantaged and traditionally underrepresented groups into science and engineering. The PI and a small group of undergraduate assistants will engage the students by asking questions such as "Why doesn't an airplane fly like an insect?", and then lead interactive discussions and demonstrations that encourage broad participation.