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

这项教师早期职业发展（Career）资助将促进对气液矿物界面活性颗粒的科学理解，并利用所获得的见解来改变多孔介质中多相流的自适应控制范式。多孔介质中的多相流动主要受孔隙流体流变特性和气-液-矿相互作用的控制。通过添加主动悬架，这些过程可以得到很大的改变。主动悬架是一种自我推进的物体，可以注入能量，产生机械应力，或在流体中产生流动。活性颗粒正在革新许多工业和科学领域，例如用于动态密封的铁磁颗粒，用于靶向递送药物的微型机器人，促进细胞运动的分子马达，以及将水调节为超流体的活动细菌。研究多孔介质中的活性流体可以革新地质系统基础设施和地下能源的商业技术，从而提高美国的经济和技术竞争力。特别是，将主动悬架技术转化为资源回收和可靠废物处理的实际改进，可以改造和造福社会。从这个奖项中获得的知识也可以为微生物感染、生物微型机器人设计和有针对性的交付提供见解，这些都与社会中个人福祉相关的许多环境和健康问题有关。这项职业补助金的研究和教育活动将整合在一起，以促进能源岩土工程的跨学科社区，激发不同学生群体对岩土工程和STEM学科的兴趣，并向公众广泛传播岩土工程在解决与可持续性和能源相关的全球挑战方面的关键作用。这笔拨款还将促进PI与参与者之间的长期指导关系，这将加强和多样化代表性不足的少数族裔STEM管道。这项职业补助金的研究目标是了解和模拟活动细菌与气液矿物界面之间的相互作用。将采用实验、数值和分析模型相结合的方法来研究三种大肠杆菌菌株在不同运动状态下的影响(1)在气液界面，(2)在悬垂液滴和固滴中，(3)在载菌界面通过孔隙空间迁移时，以及(4)在多孔介质的润湿和干燥过程中。本研究将最终(1)量化悬浮活性颗粒的气液界面张力，(2)了解运动对悬垂液滴中细菌水动力分散的作用，(3)评估细菌在疏水性和亲水性矿物表面上钉住或脱固液滴的运动性，(4)测量承载活性颗粒的界面通过孔喉迁移时的毛细特征。(5)模拟多孔介质中干湿过程中运动和非运动大肠杆菌的宏观传播动力学。活性孔隙流体是非平衡系统，呈现出新颖的特征，在科学上是有趣的。这项资助支持了对活性颗粒负载界面非线性行为的基本理解，这些界面在通过不规则孔隙空间迁移时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、提高资源采收率、自适应控制和定向输送流体（以及相关的热量、营养物质和质量）在多孔介质中的传递提供了创新方法。通过该项目获得的新知识和技术可用于开发利用人造活性颗粒改变许多基本土壤现象的破坏性技术，如渗透、排水、固结和液化。这项职业生涯补助金的综合教育目标是让能源岩土工程的跨学科社区参与进来，并提高公众对岩土工程在解决与可持续发展和能源可行社会有关的全球挑战中的作用的认识。为了实现这些目标，将建立一个涉及K-12 STEM学生（通过研究、实验、分析、学习REAL项目）、本科生和研究生研究助理以及高中教师（通过格鲁吉亚教师GIFT项目实习生奖学金）的地下能量垂直整合项目，以参与一个跨学科社区，研究通过多孔介质的活性流体。研究和教育成果将通过提高科学素养来传播，为亚特兰大K-12学校和夏令营设计与地下流动相关的课堂挑战问题，并开发一个移动应用程序，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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.