Collaborative Research: Cohesive Immersed Granular Flows: Multiscale Experiments and Particle-Resolved Modeling

Immersed granular materials such as river and seabed sediments and industrial slurries consist of small particles dispersed in a liquid. When these particles stick together, the bulk behavior of the slurry becomes highly complex. These cohesive effects determine whether a riverbed erodes, a coastal slope collapses, or an industrial process is successful. Despite its importance, predicting the bulk behavior of cohesive immersed grains is difficult. This project addresses the challenge of predicting how microscopic adhesive forces between individual particles control the large-scale flow of immersed cohesive granular materials. The resulting knowledge will help improve models for underwater sediment transport, water treatment facilities, and industrial slurries. The project will combine a novel laboratory approach, utilizing controllable "sandcastle-like" bonds between particles with advanced particle-resolved numerical simulations that connect the particle and bulk scales. The project also includes a strong educational component that will provide research and training opportunities for high-school, undergraduate, and graduate students to develop the next-generation scientific workforce. The goal of this project is to develop a quantitative framework connecting particle-level cohesion to the macroscopic flow and rheology of immersed granular materials. The project will integrate laboratory experiments with particle-resolved numerical simulations. The experiments will directly measure the adhesive force induced by capillary bridges between immersed particles, characterize the dynamics of cohesive particle clusters using high-speed imaging, and quantify bulk flow properties including yield stress in canonical configurations like granular collapses and rotating drums. These results will be used to develop and validate a cohesive force model for the simulations, which will then probe the microstructural origins of the bulk response of the cohesive granular material. The primary scientific contribution will be the formulation of data-driven, continuum-level constitutive laws for cohesive immersed granular flows. This work will develop a validated computational tool and provide a foundational understanding to improve predictive models for cohesive sediment transport and other applications. 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.