| Geophysical flows occur in both nature and industry. Detailed understanding of the dynamics governing the motion of geophysical flows is of crucial importance to mitigate destruction caused by avalanches and pyroclastic flows. Previous studies have shown a relationship between granular flow dynamics and fluid dynamics in some aspects, with strong differences in others. One of the key similarities between fluid mechanics and granular flow dynamics is the formation of a bore/breaking wave, defined as a hydraulic or granular jump.Experiments were conducted to investigate conditions under which a granular jump forms, as well as whether the jump formed was a bore or stationary breaking wave. Experiments involved monodisperse flows of SiO2 grains down a rectangular chute under dam burst initial conditions. The angle of the bed, the mass and size of the grains, and the size and morphology of the barrier were varied, and the flows were recorded with a high speed camera with a frame rate of 500 frames per second.Flows were classified into different groupings based on formation of a bore/breaking wave upon interaction with the barrier. A Froude Number for each flow was calculated, and then compared graphically with the flow classification to determine the conditions for granular jump formation. Granular jumps were seen to form from supercritical flows dropping to a subcritical state. |
