Accumulation of particles and organisms in density stratified fluids with applications in algal blooms

密度分层流体中颗粒和生物体的积累及其在藻华中的应用

基本信息

批准号：
1604423
负责人：
Arezoo Ardekani
金额：
$ 43.5万
依托单位：
Purdue University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-08-01 至 2021-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1604423&HistoricalAwards=false
关键词：
Accumulation particles organisms density stratified

项目摘要

CBET - 1604423PI: Ardekani, ArezooMany aquatic systems, including oceans, often have regions where the water density varies with depth owing to variations in temperature and salinity. These regions of water density stratification are associated with formation of algal blooms and accumulation of marine snow particles. This project comprises computational and experimental studies to test the hypothesis that density stratification leads to enhanced horizontal clustering of particles and organisms, especially those with elongated shapes. Furthermore, the project will investigate whether density stratification suppresses convection plumes that can disperse algal cells, leading to accumulation of cells. The equations that govern the motion of fluid and particles will be solved numerically and results will be compared with experiments to visualize the motion of algal cells and particles in water with density stratification. Some algal blooms are toxic, and they pose serious problems in coastal waters, including reduced oxygen content, increased marine animal mortality, and increased fouling of marine equipment. This project will help uncover the mechanisms of algal bloom formation, which could lead to new strategies to control it. The project will provide opportunities for students at various academic levels to participate in research, and results of the project will be incorporated in fluid mechanics courses taught by the investigators. The lead investigator for this project has recently shown that water density stratification affects not only the dynamics of suspensions of algal cells, but also the motion of individual cells and marine particles. The goal of the proposed research is to quantify effects of density stratification, turbulence and shear, motility and shape of microorganisms on microstructure formation and accumulation of planktonic species by developing a large-scale computational framework to fully resolve the corresponding flows. Three-dimensional Direct Numerical Simulations of the nonlinear equations governing organism and particle transport will be implemented to gain new insights into the mechanisms governing the distribution of planktonic organisms and particles at pycnoclines. Experiments involving particle image velocimetry of algal cells and particles in density stratified liquids with an imposed turbulent flow will be used to obtain parameters needed for the computations and to validate computational results.

CBET - 1604423PI：Ardekani，Arezoo许多水生系统，包括海洋，通常都有一些区域，由于温度和盐度的变化，水密度随深度而变化。这些水密度分层区域与藻华的形成和海洋雪颗粒的积累有关。该项目包括计算和实验研究，以检验密度分层导致颗粒和生物体（尤其是那些具有细长形状的颗粒和生物体）水平聚集增强的假设。此外，该项目还将研究密度分层是否会抑制对流羽流，而对流羽流可以分散藻类细胞，导致细胞堆积。控制流体和颗粒运动的方程将得到数值求解，并将结果与实验进行比较，以可视化藻类细胞和颗粒在水中的密度分层运动。一些藻华有毒，它们给沿海水域带来严重问题，包括氧气含量降低、海洋动物死亡率增加以及海洋设备污垢增加。该项目将有助于揭示藻华形成的机制，从而可能产生新的控制策略。该项目将为不同学术水平的学生提供参与研究的机会，项目成果将纳入研究人员教授的流体力学课程中。该项目的首席研究员最近表明，水密度分层不仅影响藻类细胞悬浮液的动力学，而且影响单个细胞和海洋颗粒的运动。该研究的目标是通过开发大规模计算框架来充分解决相应的流动问题，从而量化微生物的密度分层、湍流和剪切、运动性和形状对浮游生物物种的微观结构形成和积累的影响。将实施控制生物和颗粒输运的非线性方程的三维直接数值模拟，以获得对控制重斜层浮游生物和颗粒分布的机制的新见解。涉及在强加湍流的密度分层液体中的藻细胞和颗粒的颗粒图像测速的实验将用于获得计算所需的参数并验证计算结果。