Two phase models of debris flows on natural terrains
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Geophysical mass flaws--debris flows, avalanches, landslides--can contain O (10 6 -10 10 ) m 3 or more of material, often a mixture of soil and rocks with a significant quantity of interstitial fluid. These flows can be tens of meters in depth and thousands of meters in length. The range of scales and the rheology of this mixture presents significant modeling and computational challenges. It is postulated that energy dissipation due to intergranular and basal friction is reduced by the presence of interstitial fluid, thereby carrying the flowing mass over longer distances. Modeling the complex interaction between solid and fluid phases, the mixture rheology, and the range of length and time scales presents significant modeling and computational challenges. This thesis presents a two fluid model for debris flows, a system of equations that separately represents the granular and fluid phase mass and momenta, with the interaction between the phases represented by a drag term. The mass and momentum balance laws are depth averaged to produce a "thin layer" model for mass flows. The model equations are used in a parallel, adaptive grid hyperbolic solver to simulating flows; integration of the solution software with geographic information systems enables realistic simulations over natural terrains.