Direct Numerical Simulation of Homogenous Turbulence for Planktonic Organisms

浮游生物均匀湍流的直接数值模拟

• 批准号: 9213856
• 负责人: J. Strickler
• 金额: $ 8.37万
• 依托单位: University of Wisconsin-Milwaukee
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-01 至 1993-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9213856&HistoricalAwards=false
• 关键词: Direct; Numerical; Simulation; Homogenous; Turbulence

This investigation is part of GLOBEC - Global Ocean Ecosystems Dynamics - of the U.S. Global Chenage Research Program. It is aimed at quantification of the interrelation between plankton trophodynamics and turbulence. This project stems form the fact that the literature assumes that trophodynamics and consequent population dynamics depend only on the relative density of predator and prey organisms, yet growing theoretical and empirical evidence indicates that turbulence can be alter the contact rate. Using a supercomputer, turbulence can be simulated directly from the Navier-Stokes equation (DNS) so the simulated field is a "real" flow. Flow visualization at the scale of an individual planktonic organism is the best way to educate our scientific mind. Accumulated oceanic turbulence measurements provide enough information to interpret the numerically simulated turbulence as oceanic turbulent flow. A lognormal probability density function will be used to model the statistics of turbulent flow around a planktonic organism. A computer program will be developed to reduce the amount of computation required for DNS. This program will create a kinematically correct random flow field at a high Reynolds number, which is unavailable from DNS. A data base will be established for the simulated flow field for later uses. A potential use of this data base will be to test the notion of food/ingestion signals. A stochastic model will be employed to model the behavior of a planktonic organism. Currently random walk is the only model used in Lagrangian simulations, however, the organism shows much more complex swimming behavior. A modified Auto-Regressive model will be adapted for this purpose.

这项调查是美国全球变化研究计划的全球海洋生态系统动力学的一部分。它的目的是量化浮游生物的滋养动力学和湍流之间的相互关系。这个项目源于这样一个事实，即文献假设滋养动力学和随之而来的种群动态仅取决于捕食者和猎物生物的相对密度，然而越来越多的理论和经验证据表明，湍流可以改变接触率。使用超级计算机，湍流可以直接从Navier-Stokes方程（DNS）中模拟出来，因此模拟的场是“真实的”流动。在单个浮游生物的尺度上进行流可视化是教育我们科学思维的最好方式。累积的海洋湍流测量提供了足够的信息来解释数值模拟的湍流为海洋湍流。对数正态概率密度函数将用于模拟浮游生物周围湍流的统计。将开发一个计算机程序来减少DNS所需的计算量。这个程序将创建一个运动正确的随机流场在高雷诺数，这是不可用的DNS。将建立一个模拟流场的数据库，供以后使用。这个数据库的一个潜在用途是测试食物/摄入信号的概念。一个随机模型将被用来模拟浮游生物的行为。目前，随机游动是拉格朗日模拟中唯一使用的模型，然而，生物表现出更复杂的游泳行为。修改后的自回归模型将适用于此目的。