Granular jets and hydraulic jumps on an inclined plane

C. G. Johnson, J. M. N. T. Gray (2010), J. Fluid Mech., (Submitted) • “Weak, strong and detached oblique shocks in gravity driven granular free-surface žows”, J. M. N. T. Gray, X. Cui (2007), J. Fluid Mech., 579, 113–136 • “Dežecting dams and the formation of oblique shocks in snow avalanches at Flateyri, Iceland”, X. Cui, J. M. N. T. Gray, T. Johannesson (2007), J. Geophys. Res., 112, F04012 • “Shock waves, dead-zones and particle-free regions in rapid granular free surface žows”, J. M. N. T. Gray, Y.-C. Tai, S. Noelle (2003), J. Fluid Mech. 491, 161–181 • “Friction law for dense granular žows: application to the motion of a mass down a rough inclined plane”, O. Pouliquen, Y. Forterre (2002), J. Fluid Mech., 453, 133–151 On slopes inclined at a su›ciently shallow angle, an unsteady regime of periodic pile formation and collapse is observed. Material žowing down the plane (a) is arrested by friction, and a granular jump propagates back towards the point of impingement (b, c). When it reaches the point of impingement, the žow switches to a regime of conical pile formation (d, e). At a certain size, this pile collapses, remobilising material downslope ( f, g). is material is stopped by friction (h), a granular jump propagates back towards the impingement point, and the cycle repeats.