Collaborative Research. Biologically-Generated Flow by Plankton: Numerical Simulations and Experiments

建议编号：CTS-0625976/0625898 PRINCIPAL调查员：F.Sotiropoulos/J.Yeninstitution：明尼苏达大学/佐治亚州理工学院生物流动：数值模拟和实验这笔赠款支持一项跨学科的协作研究工作，旨在整合实验生物海洋学和计算流体动力学建模方面的最新进展，以开发和验证自由游泳浮游微生物的生物真实CFD模型。将对三种不同的生物进行研究，因为已知它们依赖于不同的水生推进模式：蜗牛的拍打和磷虾的划桨(连续划桨)和桡足类(逃逸时的突起推力)。此外，它们各自的流型共同跨越了从粘性主导到过渡、惯性主导的流动范围。使用纹影光学和光学显微镜的高分辨率成像将为每个生物体提供身体和附属物的几何和运动学重建。这些信息将被用作输入，以生成解剖上真实的计算模型，其中将包括生物体身体和所有游泳附属物。将开发一种多尺度方法来解释生物体附属物中存在的微小毛发。对于单个毛状附体，将进行高分辨率、毛发分辨率的CFD模拟，以量化它们作为局部雷诺数的函数的泄漏量。这些信息将被用来在宏观(整个生物体)尺度上将每个毛茸茸的附属物建模为灵活、连续但有泄漏的表面，其平均泄漏率根据头发解析模拟确定的方式变化。用二维红外粒子图像测速仪进行流动显示，以获得高分辨率的平面速度场，包括系绳浮游生物和自由游泳的浮游生物。对孤立的个体和个体群体的大量观察将提供3D轨迹，这些轨迹将产生自由游泳的浮游生物所表现出的速度和加速度。这些测量将用于微调和验证计算模型。提出的浮游生物游泳CFD模型将为生物海洋学家提供一种新颖而强大的研究工具，可以为浮游生物对海洋中小尺度生物-物理-化学信号的反应提供新的线索。拟议的模型还将为许多重要的生物学问题提供答案，这些问题涉及浮游生物游泳的水动力学，以及此类微生物进化成利用粘性力产生推力并实现往往惊人的推进性能的机制。研究生和本科生都将参与这个项目，其独特的性质将为学生提供丰富的跨学科研究经验。学生将发展独特的技能，成为当今不断发展的研究格局中的领导者，强调并依赖于生物科学与工程学的结合。跨学科培训将通过持续的教育努力得到进一步加强，特别是佐治亚理工学院NSF IGERT和REU在水生化学和水力机械信号领域的计划。

PROPOSAL NO.: CTS-0625976 / 0625898PRINCIPAL INVESTIGATOR: F. SOTIROPOULOS / J. YENINSTITUTION: U OF MINNESOTA / GEORGIA TECH.BIOLOGICALLY-GENERATED FLOW BY PLANKTON: NUMERICAL SIMULATIONS AND EXPERIMENTS This grant supports an interdisciplinary, collaborative research effort aimed at integrating recent advancements in experimental biological oceanography and computational fluid dynamics (CFD) modeling to develop and validate biologically realistic CFD models of freely swimming planktonic micro-organisms. Three different organisms will be studied because they are known to rely on different modes of aquatic propulsion: flapping for the snail and paddling for the krill (continuous paddling) and the copepod (bursts of thrust during escape). Also their respective flow regimes collectively span the range from viscosity-dominated to transitional, inertial-dominated flows. High resolution imaging using Schlieren optics and light microscopy will provide body and appendage geometry and kinematics reconstruction for each organism. This information will be used as input to generate anatomically realistic computational models, which will include the organism body and all swimming appendages. A multi-scale approach will be developed to account for the presence of microscopic hairs in organism appendages. High resolution, hair-resolving CFD simulations will be carried for individual hairy appendages to quantify their leakiness as a function of the local Reynolds number. This information will be used to model at the macroscopic (full organism) scale each hairy appendage as flexible, continuous but leaky surface whose average leakiness varies in the manner determined from the hair-resolving simulations. Flow visualization by 2-dimensional infra-red particle image velocimetry will be carried out to obtain highly resolved planar velocity fields around both tethered and freely swimming plankton. Large volume observations of isolated individuals and groups of individuals will provide the 3D trajectories that will yield the speed and acceleration exhibited by freely swimming plankton. These measurements will be used to fine-tune and validate the computational model. The proposed CFD model of plankton swimming will provide biological oceanographers with a novel and powerful research tool that can shed new light into the response of plankton to small-scale biological-physical-chemical signals in the sea. The proposed model will also yield answers to many important biological questions pertaining to the hydrodynamics of plankton swimming and the mechanisms such microscopic organisms have evolved to leverage viscous forces to produce thrust and achieve often striking levels of propulsive performance. Both graduate and undergraduate students will be involved in this project, whose the unique nature will provide the students with a rich, interdisciplinary research experience. Students will develop unique skills to become leaders in today's evolving research landscape that emphasizes and relies on the integration of bio-sciences with engineering. Interdisciplinary training will be further enhanced by on-going educational efforts, in particular the Georgia Tech NSF IGERT and REU programs in the area of aquatic chemical and hydromechanical signaling.