Mathematical Scienaes: Computational Modeling of Swimming Organisms

福奇研究人员开发并实施了计算方法，用于对各种大小的水生动物运动的流体动力学问题进行建模。 人们感兴趣的是单个生物体的动力学及其形态与其运动特性的关系，以及游泳者群体之间及其环境之间的集体流体动力学相互作用。 研究的应用包括微孔中的细菌趋化性、生殖道中的精子运动以及主动和被动组织特性与水蛭外部游泳力学的耦合。 微孔中的细菌趋化性特别令人感兴趣，因为微生物通过多孔介质的迁移行为对于研究地下水源的污染非常重要。 尽管生物修复（微生物降解污染物的过程）具有现场规模影响，但对流体-污染物-微生物耦合系统的孔隙水平行为的详细研究仍然至关重要。 该项目的计算模型包括对流体动力学、污染物反应、扩散和对流以及游动微生物的趋化反应的详细分析。 这样可以系统地研究不同参数的影响，例如游动速度、扩散速率、微生物摄取速率，以及与微生物响应不断变化的污染物场而改变其游动方向的可能性相关的随机参数。 在实验室环境中进行检查即使不是不可能，也是很困难的。 该项目使用计算模型研究生物体游泳的方式。 研究的生物体大小各异，从细菌到水蛭。 在微孔细菌转运研究中最重要的是生物膜的生长。 在一定的物理和化学条件下，微生物相互粘附以及局部孔隙结构。 这种生物膜的生长影响局部流动特性和污染物输送，并受其影响。 计算模型能够模拟复杂的动态流体-结构相互作用。 通过在生物体的离散表示之间施加适当的结合应力来模拟团聚，这可以将它们保持在一起，或者，如果流体应力很大，则可以屈服并释放生物体。 该模型是了解微孔水平生物膜过程的强大工具。 这对环境问题具有重要影响。

Fauci The investigator develops and implements computational methods for modeling the fluid dynamics problems of aquatic animal locomotion across a wide range of animal sizes. Of interest are both the dynamics of a single organism and the relationship of its morphology to its motility properties, and the collective hydrodynamic interactions of groups of swimmers with each other and their environment. Applications studied include bacterial chemotaxis in micropores, spermatozoa motility in the reproductive tract, and the coupling of active and passive tissue properties to the external swimming mechanics of a leech. Bacterial chemotaxis in micropores is of special interest, because the transport behavior of microorganisms through porous media is important in studying the contamination of groundwater supplies. Although bioremediation, the process by which microbes degrade contaminants, has field scale implications, the detailed study of pore-level behavior of the coupled fluid-contaminant-microbial system is essential. The project's computational model includes the detailed analysis of hydrodynamics, contaminant reaction, diffusion and convection, and the chemotactic responses of the swimming microbes. This allows the systematic study of the influence of different parameters, such as swimming speed, diffusion rates, microbial uptake rates, as well as stochastic parameters relating to the likelihood with which microbes change their swimming direction in response to the evolving contaminant field. This is difficult, if not impossible, to examine in a laboratory environment. The project studies the way organisms swim, using computational models. The organisms studied vary in size from bacteria to leeches. Of paramount importance in the study of bacterial transport in micropores is the growth of biofilms. Under certain physical and chemical conditions, microbes adhere to each other and the local pore structure. This biofilm growth affects and is affe cted by the local flow characteristics and contaminant transport. The computational model has the ability to model complex, dynamic fluid-structure interactions. Agglomeration is modeled by exerting appropriate binding stresses between discrete representations of organisms, that may hold them together, or, if fluid stresses are large, may yield and release the organisms. The model is a powerful tool for understanding biofilm processes at a micropore level. This has important consequences for environmental problems.