Speaker/Affiliation: Ken Kamrin, UC Berkeley
Title: Continuum modeling and simulation of dry and saturated granular media across applications
Time: Friday, November 14 12:00pm PST
Location: EMS B210
Abstract: Granular media are common in industry, the natural world, and our day-to-day lives, but have been historically resistant to modeling. While grain-by-grain discrete element methods (DEM) exist, these are often far too costly at the length-scales of full-size industrial problems. This talk progressively develops continuum-based tools with the aim of realistic but computationally tractable full-scale flow simulation. We begin with a discussion of dry granular rheology and its essential ingredients. We provide a brief discussion of what sorts of problems can be solved accurately with a basic granular flow model, and discuss a meshless numerical method, the Material Point Method (MPM), which can be used to simulate these models up to huge deformations. Second, we do a deeper dive on how the MPM-based approach can be extended to model fluid-saturated granular flow problems using two-phase mixture theory, where the fluid and granular phases are modeled as two separate but coupled continua. This methodology is shown able to replicate experimental results for saturated granular flows over a range of conditions and packing fractions, and can be extended to account for more obscure effects, such as those giving rise to shear-thickening suspensions. This approach can be ported directly to model air-grain mixture systems, and we show how the scheme is able to simulate problems ranging from wind-based erosion to plume-cratering from rocket exhaust.
