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We observed experimentally a new regime for granular flows in an inclined channel with a flow-rate-controlled system. For high flow rates, the flow occurs atop a static granular heap whose angle is considerably higher than those usually exhibited by granular heaps. The properties of such superstable heaps (SSH) are drastically affected by a change in the(More)
We analyze theoretically the dynamics of aeolian sand ripples. In order to put the study in the context we first review existing models. This paper is a continuation of two previous papers[3, 4], the first one is based on symmetries and the second on a hydrodynamical model. We show how the hydrodynamical model may be modified to recover the missing terms(More)
Unlike most fluids, granular materials include coexisting solid, liquid or gaseous regions, which produce a rich variety of complex flows. Dense flows down inclines preserve this complexity but remain simple enough for detailed analysis. In this review we survey recent advances in this rapidly evolving area of granular flow, with the aim of providing an(More)
We performed numerical simulations of one-bead collision on the surface of a static granular medium. The simulations have been done for two- and three-dimensional packings of beads. The effect of the incident bead velocity, the shot angle, the mechanical parameters and the packing structure are analyzed for ordered and disordered 2D packings and only(More)
We present stratigraphic measurements of humidity and bulk density beneath the surface of a barchan dune obtained with a capacitance probe. A model shows that air seeping through the sand bed in response to spatial variations of static pressure along the ripple surface guides water vapor through ripple crests and gradually stores dust beneath troughs. The(More)
We report on wind tunnel measurements on saltating particles in a turbulent boundary layer and provide evidence that over an erodible bed the particle velocity in the saltation layer and the saltation length are almost invariant with the wind strength, whereas over a nonerodible bed these quantities vary significantly with the air friction speed. It results(More)
We study fully developed, steady granular flows confined between parallel flat frictional sidewalls using numerical simulations and experiments. Above a critical rate, sidewall friction stabilizes the underlying heap at an inclination larger than the angle of repose. The shear rate is constant and independent of inclination over much of the flowing layer.(More)
We report on wind-tunnel measurements of particle velocity distribution in aeolian transport. By performing extended statistics, we show that for saltation occurring over an erodible bed the vertical lift-off velocity distributions deviate significantly from a Gaussian law and exhibit a long tail accurately described by a lognormal law. In contrast,(More)
We propose a model for the propagation of energy due to the impact of a granular projectile on a dense granular medium. Energy is transferred from grain to grain during binary collision events. The transport of energy may then be viewed as a random walk with a split of energy during successive collisions. There is a qualitative and quantitative agreement(More)
We report on experimental studies of the collision process between an incident bead and a three-dimensional granular packing (made of particles identical to the impacting one). The understanding of such a process and the resulting ejection of particles is, in particular, crucial to describe eolian sand transport. We present here an extensive experimental(More)