Mathematical Scienaes: Computational Modeling of Swimming Organisms

研究人员福奇开发并实施了计算方法，用于模拟水生动物在各种动物大小范围内的运动的流体力学问题。令人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，以及游泳者群体彼此之间及其所处环境的集体水动力相互作用。所研究的应用包括细菌在微孔中的趋化性，精子在生殖道中的运动，以及主动和被动组织特性与水蚤外部游泳机制的耦合。细菌在微孔中的趋化性具有特殊的意义，因为微生物在多孔介质中的传输行为对于研究地下水供应的污染是非常重要的。尽管微生物降解污染物的生物修复过程具有现场规模的影响，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是必不可少的。该项目的计算模型包括对水动力学、污染物反应、扩散和对流的详细分析，以及游泳微生物的趋化反应。这使得系统地研究不同参数的影响，如游泳速度、扩散速度、微生物摄取速度，以及与微生物改变其游泳方向以响应不断演变的污染场的可能性有关的随机参数。这即使不是不可能，也很难在实验室环境中进行检测。该项目使用计算模型研究生物体的游泳方式。所研究的生物体大小不一，从细菌到水蚤。在研究细菌在微孔中的传输时，最重要的是生物膜的生长。在一定的物理和化学条件下，微生物相互黏附，并附着在局部的孔隙结构上。这种生物膜生长受局部流动特性和污染物运移的影响和影响。该计算模型能够模拟复杂的、动态的流体-结构相互作用。凝聚是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的，这种结合应力可以将它们结合在一起，或者，如果流体应力很大，可能会屈服并释放生物体。该模型是在微孔水平上理解生物膜过程的有力工具。这对环境问题有着重要的后果。

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.