This project will investigate the governing processes that control fluid movement across unsaturated fracture intersections using tested experimental and theoretical methods and determine what parameters are important to incorporate into large-scale models. Securing a comprehensive understanding of transport through fractures is a matter of immense national importance in our efforts to secure both the safety of long-term nuclear waste and to help ensure the quality of our nation's future water supply. Three project phases will advance our understanding of this important subject: (1) identify the "effective dynamic contact angle" as a volume averaging parameter in order to describe net transport through the fractured system determined by intersection dynamics; (2) quantify the role of intersection geometry on flow dynamics; and (3) develop predictions for field-scale plume evolution (e.g., focusing and dispersal) using the concept of equivalent fibrous media. Expected results are: (a) advance the understanding of the physics of multi-phase flow by identifying governing processes that control mode selection at intersections; and (b) resolve a leading uncertainty in predictive modeling by developing a geologically based framework for incorporating intersection dynamics into field-scale models. An educational component that integrates research and education for upper division undergraduate and PhD students has been designed to attract top qualified students into research science careers. Top-tier undergraduate science majors will be recruited to work in cross-disciplinary research-education groups and participate in all aspects of the research project, culminating with presentations at a national conference. The pedagogical technique selected, i.e., integrated research and capacity development, will serve to infuse learning with the excitement of discovery, greater appreciation of skill-development, and give invaluable encouragement towards completion of both undergraduate studies and graduate work. The PhD student-mentor will participate in the development of all pedagogical materials, which will include a new hands-on exploratory course in fluid physics, and workshops for in-service K-12 teachers in collaboration with the NSF G-K12 and SMILE programs. The educational and outreach portion of this project are specifically designed with the vision to ensure that the nation's supply of scientists are equipped to surmount the technical challenges of the future.
