Flow of variably fluidized granular masses across three-dimensional terrain: 2. Numerical predictions and experimental tests

摘要: Numerical solutions of the equations describing flow variably fluidized Coulomb mixtures predict key features dry granular avalanches and water-saturated debris flows measured in physical experiments. These include time-dependent speeds, depths, widths as well geometry resulting deposits. Three-dimensional (3-D) boundary surfaces strongly influence dynamics because transverse shearing cross-stream momentum transport occur where topography obstructs or redirects motion. Consequent energy dissipation can cause local deceleration deposition, even on steep slopes. Velocities surge fronts other discontinuities that develop cross 3-D terrain are predicted accurately by using a Riemann solution algorithm. The algorithm employs gravity wave speed accounts for different intensities lateral stress transfer regions extending compressing with degrees fluidization. Field observations experiments indicate which fluid plays significant role typically have high-friction margins weaker interiors partly pore pressure. Interaction strong perimeter weak interior produces relatively steep-sided, flat-topped To simulate these effects, we compute pressure distributions an advection-diffusion model enhanced diffusivity near margins. Although challenges remain evaluating diverse geophysical flows, depth-averaged mixture provide powerful tool interpreting predicting behavior. They means modeling rock avalanches, pyroclastic related phenomena without invoking calibrating rheological parameters questionable significance.