Collaborative Research: Wettability Control on the Mechanics of Fracture in Granular and Porous Media

裂隙网络在颗粒和多孔介质中的发展方式对于从天然气勘探到现代燃料电池失效的广泛应用是一个重要的问题。该奖项将支持有关流体流动如何驱动颗粒系统中裂缝网络演化的基础研究。最近的观察表明，“润湿性”，一种衡量流体和颗粒介质之间吸引力的指标，可能在控制裂缝响应方面发挥着以前从未探索过的重要作用，这一调查结果得到了支持。这项研究的见解将帮助科学家和工程师确定最佳工艺条件，以根据需要增加或减少裂缝生长。新实验和模型的开发还将为来自代表性不足群体的新博士生提供培训，传授必要的技能，使他们能够解决流动诱导裂缝中的重要和具有挑战性的技术问题。最后，作为这项努力的一部分，计划通过与全国妇女权利委员会建立新的伙伴关系，向STEM地区人数不足的少数族裔学生开展外联活动。特别是，麻省理工学院和杜克大学将联合举办土木工程和环境工程新兴研究的研讨会，以帮助这些团体的学生寻求这一领域的暑期研究机会。该项目侧重于颗粒和多孔介质中毛细管断裂的形态动力学，重点是润湿性的作用。特别是，它涉及的反应的理想化细胞，密实地填充准多孔介质和饱和粘性防护液。观察表明，即使在粘性力占主导地位的高注入速率下，裂缝形态对润湿性能的依赖程度也高得令人惊讶。主要目标是显著促进目前对毛细管断裂的理解，并开发在该领域有用和可预测的基于模型的模拟能力。这将通过开发一套综合的新颖实验和伴随的计算工具来实现，这些工具允许充分探索这些系统的新兴模型。这一联合努力将允许研究几个悬而未决的问题，例如促进稳定压裂的条件。该项目试图回答的一个中心问题涉及颗粒介质的表观“断裂韧性”，以及当介质接近更传统的多孔弹性固体时，这种韧性是如何演变的。这一奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The way that fracture networks develop in granular and porous media is a question of importance to a wide range of applications, ranging from natural gas exploration to the failure of modern fuel cells. This award will support fundamental studies of how fluid flow can drive the evolution of fracture networks in granular systems. The inquiry is supported by recent observations indicating that "wettability", a measure of attraction between the fluids and the granular media, may play a vital and previously unexplored role in governing the fracture response. Insights from this study will help scientists and engineers identify the optimal process conditions to either increase or decrease fracture growth, as desired. The development of the new experiments and models will also provide training for new doctoral students from under-represented groups, transferring the requisite skills for them to address technologically important and challenging problems in flow-induced fracture. Finally, outreach activities to under-represented minority students in the STEM area are planned as part of this effort through a novel partnership with NC-SLI. In particular, a joint MIT-Duke workshop on emerging research in civil and environmental engineering will be set up to facilitate students from these groups pursuing summer research opportunities in this area.This project is focused on the morphodynamics of hydrocapillary fracture in granular and porous media with an emphasis on the role of wettability. In particular, it concerns the response of idealized cells that are densely packed with quasi-porous media and saturated with a viscous defending fluid. Observations indicate a surprisingly strong dependence of fracture morphology on wetting properties, even at high injection rates where viscous forces dominate. The main objectives are to significantly advance the current understanding of hydrocapillary fracture, and to develop model-based simulation capabilities that are useful and predictive in this space. This will be effected through the development of an integrated suite of novel experiments and accompanying computational tools that allow emerging models of these systems to be fully explored. This joint effort will allow several open questions to be examined, such as the conditions that promote stable fracturing. A central question this project seeks to answer concerns the apparent "fracture toughness" of granular media, and how such toughness evolves as the media approaches a more conventional poroelastic solid.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.