This project is motivated by recent observations of evolving fracture networks in tightly-packed systems of particles, or particle rafts, interacting with fluids. Research supported by this award is focused on computational models and simulations of these systems. Simulations will enable detailed investigations into their behavior, and help to answer open questions such as why seemingly small perturbations in particle packing give rise to dramatically different fracture patterns. The tightly packed particle network is an idealized porous medium, and the injection of surfactant is what drives the growth of the fracture networks. This type of coupling between fluid flow and crack growth is central to many problems of technological relevance, including hydraulic fracturing and corrosion-assisted fracture. The tabletop experiments are simple and cost effective to study particle systems in detail. The effort involves outreach activities to public elementary schools in North Carolina, where movies of the simulations and experiments of fracture networks will be shown. These in-class demonstrations will be used as a launching point to introduce students to basic programming concepts at a young age.
The research supported by this award is aimed at using simulation science to determine the influence of particle packing, size distributions, and surfactant injection on fracture evolution in particulate systems. The simulations will provide a means to consider systems beyond the practical limits of experimental testing, such as a much broader range of particle sizes and packing configurations. In the process, fundamental contributions will be made in applied mechanics and computational science. These include: 1) a chemo-poro-elasticity based theory for the fracturing of particulate raft systems; and 2) multi-scale, coupled finite-element and molecular dynamics methods that can handle a range of time-scales, from the fast scales of particle interactions to the much slower scales of surfactant diffusion. These models and simulations will be used to study recent experiments in the dynamics of fracture of particulate rafts, focusing on the important roles of particle heterogeneity and surfactant injection.
