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

从天然气勘探到现代燃料电池的失效，裂缝网络在颗粒状和多孔介质中的发育方式对广泛的应用具有重要意义。该奖项将支持流体流动如何驱动颗粒系统中裂缝网络演化的基础研究。最近的观察结果表明，“润湿性”（衡量流体与颗粒介质之间的吸引力）可能在控制裂缝响应方面起着至关重要的作用，这是以前未被发现的。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。新实验和模型的发展也将为来自代表性不足群体的新博士生提供培训，为他们提供必要的技能，使他们能够解决流致压裂中技术重要和具有挑战性的问题。最后，通过与NC-SLI的新型合作伙伴关系，计划在STEM领域为代表性不足的少数民族学生开展外展活动。特别值得一提的是，麻省理工学院和杜克大学将联合举办一个关于土木和环境工程新兴研究的研讨会，以促进这些团体的学生在这一领域寻求暑期研究机会。本项目主要研究颗粒状和多孔介质中水毛细管裂缝的形态动力学，重点研究润湿性的作用。特别是，它涉及到理想细胞的响应，这些细胞密集地挤满了准多孔介质，并被粘性防御流体饱和。观察结果表明，裂缝形态对润湿特性的依赖性非常强，即使在高注入速率下，粘性力也占主导地位。主要目标是显著提高对水毛管裂缝的现有认识，并开发基于模型的模拟能力，在该领域具有实用性和预测性。这将通过开发一套完整的新实验和伴随的计算工具来实现，这些工具允许这些系统的新兴模型得到充分的探索。这一共同努力将使几个悬而未决的问题得以研究，例如促进稳定压裂的条件。该项目试图回答的一个核心问题是颗粒介质的明显“断裂韧性”，以及当介质接近更传统的孔隙弹性固体时，这种韧性如何演变。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。

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.