CAREER: Transforming Multiphase Flow in Porous Media from Passive Pore Fluids to Active Suspensions of Motile Bacteria

这项学院早期职业发展(CALEAR)补助金将促进对气体-液体-矿物界面活性颗粒的科学理解，并利用所获得的见解转变多孔介质中多相流自适应控制的范例。多孔介质中的多相渗流主要受孔隙流体的流变性和气体-流体-矿物相互作用的影响。这些过程可以通过添加主动悬浮液来大幅改变，主动悬浮液是可以注入能量、产生机械应力或在流体中产生流动的自动推进物体。活性粒子正在给许多工业和科学领域带来革命性的变化，例如用于动态密封的铁磁性粒子，用于靶向药物输送的微型机器人，促进细胞运动的分子马达，以及将水调节为超流体的运动细菌。研究多孔介质中的活性流体可以革新地球系统基础设施和地下能源方面的商业技术，这将增加美国的经济和技术竞争力。特别是，将使用主动悬架的技术转化为资源回收和可靠废物处理的实际改进，可以改变和造福社会。从这一奖项中获得的知识还可以提供对微生物感染、微型生物机器人设计和定向交付的见解，这些都与社会上与个人福祉有关的许多环境和健康问题有关。这一职业补助金的研究和教育活动将被整合起来，以促进能源岩土技术方面的跨学科社区，激发不同学生群体对岩土技术和STEM学科的兴趣，并扩大向公众传播岩土工程在应对与可持续发展和能源有关的全球挑战方面的关键作用。这笔赠款还将促进PI和参与者之间的长期指导关系，这将加强和多样化代表不足的少数民族STEM管道。这项职业赠款的研究目标是了解可移动细菌和气液矿物界面之间的相互作用并建立模型。通过实验、数值模拟和分析相结合的方法，研究了三种具有不同运动能力的大肠杆菌菌株(1)在气液界面，(2)在悬浮液和固着液滴中，(3)作为细菌界面在孔隙空间中迁移，以及(4)在多孔介质中的湿润和干燥过程中的影响。这项研究最终将(1)量化悬浮活性颗粒的气液界面张力，(2)了解运动性对悬浮液滴中细菌的流体动力学分散的作用，(3)评估细菌在疏水和亲水矿物表面钉扎或脱附固着液滴的运动性，(4)测量毛细管特征，作为携带活性颗粒的界面通过孔喉迁移，以及(5)模拟运动和静止的大肠杆菌在多孔介质中的润湿和干燥过程中的宏观传播动力学。活性孔隙流体是非平衡系统，呈现出具有科学意义的新特征。这笔赠款支持了对活性颗粒界面非线性行为的基本理解，当它们在不规则的孔隙空间中迁移时，它们表现出独特的毛细特征和屈曲机制。微生物运动如何改变多相流模式的研究成果为地下流动管理、增强资源回收、适应性控制和多孔介质中流体(以及相关的热、营养和质量)传输的定向输送提供了创新的方法。通过该项目获得的新知识和新技术可用于开发使用人造活性颗粒改变许多基本土壤现象的破坏性技术，如渗漏、排水、固结和液化。这一职业资助的综合教育目标是让跨学科的社区参与能源岩土技术，并让公众更多地认识到岩土技术在应对与可持续和能源可行的社会相关的全球挑战中所扮演的角色。为了实现这些目标，将建立一个关于地下能源的垂直综合计划，涉及K-12 STEM学生(通过研究、实验、分析、学习REAL计划)、本科生和研究生研究助理以及高中教师(通过佐治亚州教师实习生奖学金计划)，以通过多孔介质接触活跃流体的跨学科社区。研究和教育成果将通过提高科学素养、为亚特兰大K-12学校和夏令营设计与地下水流有关的课堂挑战问题，以及开发一款移动应用程序来传播，学生和公众用户可以选择不同的天然或人造多孔材料来可视化各种流体的流动和添加的活性颗粒的影响。这些产品还将在Tellus科学博物馆、亚特兰大科学节和能源博览会上展出。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development (CAREER) grant will promote the scientific understanding of active particles at gas-liquid-mineral interfaces and use the insights gained to shift the paradigm in adaptive control of multiphase flow in porous media. Multiphase flow in porous media is mainly governed by the rheological properties of pore fluids and the gas-fluid-mineral interactions. These processes can be substantially altered by adding active suspensions, which are self-propelling objects that can inject energy, generate mechanical stress, or create flows within fluids. Active particles are revolutionizing many industrial and scientific fields, such as ferromagnetic particles for dynamic sealing, micro-robots for targeted delivery of drugs, molecular motors to facilitate cell locomotion, and motile bacteria to tune water into superfluids. Studying active fluids in porous media can renovate commercial techniques in geosystems infrastructure and subsurface energy that will increase the economic and technological competitiveness of the United States. Particularly, translating the technology of using active suspensions into the practical improvement of resource recovery and reliable waste disposal can transform and benefit society. Knowledge gained from this award can also provide insights into microbial infection, bio-microrobots design, and targeted delivery that are relevant to many environmental and health issues pertaining to the well-being of individuals in society. Research and education activities of this CAREER grant will be integrated to foster a cross-disciplinary community in energy geotechnics, inspire the interests of diverse student groups in geotechnics and STEM subjects, and broaden dissemination to the public of the critical role of geotechnical engineering in addressing global challenges related to sustainability and energy. This grant will also facilitate long-term mentoring relationships between the PI and participants, which will strengthen and diversify the underrepresented minority STEM pipeline.The research objective of this CAREER grant is to understand and model the interactions between motile bacteria and gas-liquid-mineral interfaces. Combined experimental, numerical and analytical modeling will be performed to investigate the effects of three strains of Escherichia coli with different motility (1) at the gas-liquid interface, (2) in pendant and sessile droplets, (3) as bacteria-laden interface migrating through pore space, and (4) during wetting and drying processes in porous media. This research will ultimate (1) quantify the gas-liquid interfacial tension with suspended active particles, (2) understand the role of motility on the hydrodynamic dispersion of bacteria in a pendant droplet, (3) evaluate bacteria motility to pin or depin sessile droplets on hydrophobic and hydrophilic mineral surfaces, (4) measure the capillary signature as active-particle-laden interfaces migrating through pore throats, and (5) model the macroscopic spreading dynamics of motile and nonmotile Escherichia coli during the wetting and drying processes in porous media. Active pore fluids are non-equilibrium systems, present novel features that are interesting scientifically in their own rights. This grant supports the fundamental understanding of the non-linear behavior of active-particle-laden interfaces, which exhibit unique capillarity signatures and buckling mechanisms as they migrate through irregular pore spaces. Research findings of how microbial motility alters multiphase flow patterns provide innovative approaches to subsurface flow management, enhanced resource recovery, adaptive control and targeted delivery of fluids (and associated heat, nutrients, and mass) transfer in porous media. The new knowledge and techniques obtained through this project can be used to develop disruptive technologies of using man-made active particles to alter many fundamental soil phenomena, such as seepage, drainage, consolidation, and liquefaction. Integrated educational objectives of this CAREER grant are to engage a cross-disciplinary community in energy geotechnics and generate greater awareness amongst the public about the geotechnical role in addressing global challenges related to sustainable and energy-viable society. To achieve these objectives, a Vertically Integrated Program on subsurface energy involving K-12 STEM students (through the Research, Experiment, Analyze, Learn REAL program), undergraduate and graduate research assistants, and high school teachers (through the Georgia Intern Fellowship for Teacher GIFT program) will be established to engage a cross-disciplinary community in active fluids through porous media. The research and educational outcomes will be disseminated through increasing scientific literacy, designing classroom challenge problems related to subsurface flow for Atlanta K-12 schools and summer camps, and developing a mobile app that students and public users can select different natural or man-made porous materials to visualize the flow of various fluids and the impacts of added active particles. These products will also be presented at the Tellus Science Museum, Atlanta Science Festival, and Energy Expo.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.