Collaborative Research: Functional morphology of a high-efficiency filtration mechanism identified in manta rays

蝠鲼和魔鬼鱼是大型鱼类，它们通过吞噬大量海水，用特殊的过滤结构提取浮游生物，并通过鳃缝排出过滤后的水。这些动物利用一种高效的过滤机制，即跳弹分离，这与先前描述的生物或工业过滤过程不同。该项目将采用多学科方法来研究这一独特系统的流体动力学和过滤力学。该项目将描述过滤结构的解剖结构，确定结构的形状如何影响过滤器周围的流动，并确定产生的流动模式如何影响颗粒过滤。这项工作将提供重要的见解生理学生态学上重要的和受威胁的动物群体。此外，在从减轻大规模环境污染事件到常规废水处理等应用中，还需要改进过滤策略。该项目将阐明一种新型高效过滤过程的机制，并具有相当大的潜力，可以导致先进的生物过滤系统。这项研究还将为本科生、研究生和博士后科学家提供有价值的培训，并支持活动，以吸引学龄学生，让他们接触生物力学和生物启发工程。流动鱼类（蝠鲼和魔鬼鱼）的过滤装置是一种高度专业化的鳃耙结构。长期以来，人们一直认为耙子的作用就像筛子过滤器，只是捕获比孔径大的颗粒。然而，最近的研究表明，耙利用了一种独特的过滤机制，即弹跳分离，在这种过滤机制中，复杂的流场导致浮游生物颗粒从过滤器表面反冲出来，并集中在口腔内。这种过滤过程具有几个有利的特性，包括有效地分离小于孔径的颗粒，具有高度的抗堵塞性，并且具有较低的水动力阻力。本项目将研究这一机制背后的流体动力学过程以及影响其性能的形态因素。本研究采用多管齐下的方法，包括解剖学研究（微计算机断层扫描）、实验流体力学（粒子图像测速和过滤效率测量）和理论建模（计算流体动力学）。目标1将研究过滤器表面的小规模物理过程，确定单个浮游生物颗粒如何与过滤器相互作用，以及这种相互作用如何受到过滤器形态的影响。目的2将检查在口腔中发展的大规模流动模式，并将确定这种流动如何影响过滤力学。目标3将使用这些过程的理解来创建和优化仿生工程过滤系统。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Mantas and devil rays are large fishes that feed by engulfing massive volumes of seawater, extracting plankton with a specialized filter structure, and expelling filtered water through the gill slits. These animals utilize a highly-efficient filtration mechanism, ricochet separation, that is distinct from previously-described biological or industrial filtration processes. This project will use a multidisciplinary approach to examine the fluid dynamics and filtration mechanics of this unique system. This project will characterize the anatomy of the filtering structure, identify how the shape of the structure affects the flow around the filter, and determine how the resulting flow patterns affect particle filtration. This work will provide critical insights into the physiology of an ecologically important and threatened group of animals. In addition, there is substantial need for improved filtering strategies for use in applications ranging from mitigating large-scale environmental contamination events to routine wastewater treatment. This project will elucidate the mechanics of a novel and highly-efficient filtration process, and has considerable potential to lead to advanced, bioinspired filtration systems. This research will also provide valuable training for undergraduate, graduate, and post-doctoral scientists and support activities to engage school-aged students and expose them to biomechanics and bioinspired engineering.The filtering apparatus of mobulid fishes (mantas and devil rays) is a highly-specialized gill-raker structure. It has long been believed that the raker functioned as a sieve filter, simply trapping particles larger than the pore size. However, recent work has shown that the raker utilizes a unique filtration mechanism, ricochet separation, in which complex flow fields cause plankton particles to recoil off the filter surfaces and become concentrated within the buccal cavity. This filtration process has several favorable properties including that it efficiently separates particles smaller than the pore size, is highly resistant to clogging, and has low hydrodynamic resistance. This project will examine the fluid dynamic processes underlying this mechanism and the morphological factors that influence its performance. This research uses a multipronged approach that includes anatomical studies (micro computed tomography), experimental fluid mechanics (particle image velocimetry and filtration efficiency measurements), and theoretical modeling (computational fluid dynamics). Aim 1 will investigate the small-scale physical processes at the surface of the filter, identifying how individual plankton particles interact with the filter and how this interaction is affected by the morphology of the filter. Aim 2 will examine the large-scale flow patterns that develop in the mouth and will determine how this flow influences the filtration mechanics. Aim 3 will use an understanding of these processes to create and optimize bio-inspired engineered filtration systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.