Subcritical and supercritical granular flow around an obstacle on a rough inclined plane

A blunt obstacle in the path of a rapid granular avalanche generates bow shock (a jump thickness and velocity), region static grains upstream obstacle, grain-free downstream. Here, it is shown that this interaction qualitatively altered if incline on which flowing changed from smooth to rough. On rough incline, friction between depends flow speed, allows both (supercritical) slow (subcritical) steady uniform avalanches. For supercritical experimental flows, material diverted around by formation dead zone obstacle. Downslope, vacuum forms, but, contrast flows beds, levees form at boundary flow. In slower, subcritical, smoothly without forming shock. After stops, signatures zone, (in subcritical flows) deeper upslope are frozen into deposit. To capture behaviour, numerical simulations performed with depth-averaged model includes frictional hysteresis viscous terms, needed accurately deposited regions. These results may be directly relevant geophysical mass snow avalanches, over terrain impact barriers or other infrastructure.