SMALL GRANTS FOR EXPLORATORY RESEARCH (SGER): DEVELOPMENT AND USE OF A VISUALIZATION TECHNIQUE TO BETTER DEFINE MECHANISMS FOR PARTICLE TRANSPORT IN POROUS MEDIA

0551834德国人了解多孔介质中的颗粒传输对于涉及地下流动和传输、水和废水处理以及土壤土壤学的许多问题都很重要。颗粒在多孔介质中的运移行为是复杂的。影响这一行为的因素包括颗粒密度、尺寸和表面化学、水化学、间隙速度和多孔介质的特性。在生物颗粒的情况下，运动性、趋化性、生长和衰变也是有影响的。基于间歇和柱状测试的实验程序已经对颗粒在多孔介质中的传输获得了重要的认识。尽管如此，这种性质的工作不能实时解决控制多孔介质内部颗粒传输的过程。这限制了从这种实验方法中可以获得的理解的规模。为了进一步了解控制颗粒在多孔介质中的去向和传输的基本过程，需要使用其他方法来可视化研究颗粒在多孔介质中的行为。在先前的工作中，该方案的研究人员开发了一种可视化技术来研究颗粒在多孔介质中的内部行为。这项技术的使用使得关于粒子输运行为的新假设得以提出。这一探索性研究项目的目标是进一步发展新的可视化技术，并为关于粒子输运行为的新假说提供进一步的支持。具体地说，该项目将：1.扩展新的可视化技术，以实现对颗粒行为的更好分辨率，包括在微观尺度上对单个颗粒轨迹的分辨率以及在宏观尺度上区分水相和固相颗粒。无可辩驳地证明，在不利的静电条件下，在非布朗粒子的传输过程中，观察到的粒子附着率随传输距离的下降可归因于重力沉积导致较重粒子的早期过滤，以及3。建立微米级颗粒的流动方向对颗粒输运的影响，这些颗粒的行为理论上受布朗运动支配。布罗德影响研究将提供一种可视化工具，能够在空间和时间上解析多孔介质内部微观和宏观颗粒的浓度。这项研究还将提高对影响颗粒与介质固相相互作用的附着和脱离机制的理解。特别是，它将解释为什么在不利的静电条件下，不可逆粒子附着率随着输运距离的增加而降低。将为一名研究生提供研究培训。本科生也将通过麻省理工学院的本科生研究机会计划参与这项研究。

0551834 GermaineUnderstanding particle transport in porous media is important to a number ofproblems involving subsurface flow and transport, water and waste-water treatment, andsoil pedology. The migration behavior of particles in porous media is complex. Factorsinfluencing this behavior include the particle density, size and surface chemistry, thewater chemistry, the interstitial velocity, and the characteristics of the porous medium. Inthe case of biological particles, motility, chemotaxis, growth and decay are alsoinfluential.Considerable insight into particle transport in porous media has been gained fromexperimental programs based on batch and column testing. Nonetheless, work of thisnature cannot resolve, in real-time, the processes governing particle transport in theinterior of a porous medium. This limits the scale of understanding that can be gainedfrom such experimental approaches. In order to further understanding of the fundamentalprocesses governing particle fate and transport in porous media, alternative methods thatinvolve visualization studies of particle behavior within a porous medium are needed.In prior work, the Investigators of this proposal developed a visualizationtechnique to study particle behavior in the interior of a porous medium. Use of thistechnique enabled the proposition of new hypotheses regarding particle transportbehavior. The goals of this exploratory research project are to further the newvisualization technique, and to provide further support for the emerging hypotheses onparticle transport behavior. Specifically, the project will:1. Extend the new visualization technique to enable better resolution of particlebehavior, including resolution of individual particle tracks at the micro-scale anddistinction between aqueous and solid phase particles at the macro-scale.2. Prove, irrefutably, that, during non-Brownian particle transport underunfavorable electrostatic conditions, observations of decreasing particle attachment ratewith transport distance are attributable to the early filtration of heavier particles as aresult of gravitational sedimentation, and3. Establish the impact of flow direction on particle transport for micron-sizedparticles whose behavior is, theoretically, dominated by Brownian motion.Broader Impacts The proposed research will provide a visualization tool that canspatially and temporally resolve microscopic and macroscopic particle concentrations inthe interior of a porous medium. The research will also improve understanding ofattachment and detachments mechanisms that impact particle interaction with a medium'ssolid phase. In particular, it will provide an explanation for why irreversible particleattachment rates decrease with transport distance under unfavorable electrostaticconditions. Research training will be provided for one graduate student. Undergraduatestudents will also be engaged in the research through MIT's Undergraduate ResearchOpportunities Program.