Diffuse and steep jumps in steady-state granular flows
Ressauts raides et diffus dans les écoulements granulaires stationnaires
Résumé
The design of civil engineering structures such as protection dams and mitigation walls against the impact of large-scale geophysical flows requires a fundamental knowledge of the underlying physics of granular flows around obstacles. It is now well established that large discontinuities in depth and velocity, namely standing waves, jumps and shocks, can be formed throughout the flowing granular body, at the upstream side of the obstacle. The current paper describes a newly established small-scale laboratory apparatus, a tank feeding a chute, designed for studying in detail the shape of the granular jumps across a wide range of flow conditions. These flow conditions include variation of the input flow rate, chute inclination and basal roughness. The preliminary tests presented here highlight the existence of complex transitions from strong shocks to very diffuse jumps either two or three dimensional in shape, and the possible development of a basal stagnant zone downstream of the jump.