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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)
An intriguing feature of granular matter is the close coexistence of solid-like regions and liquid-like flows. We study steady, fully-developped, granular flows confined between parallel vertical sidewalls. The sidewall friction stabilizes the underlaying heap at an inclination exceeding the angle of repose and increasing with flow rate. Our experiments(More)
BACKGROUND There is a current debate regarding the association of human herpesvirus 6 (HHV-6) infection and drug reaction with eosinophilia and systemic symptoms (DRESS). METHODS Seven consecutive patients hospitalized with DRESS were enrolled in a prospective study to evaluate evidence of active HHV-6 infection. OBSERVATIONS The imputable drugs were(More)
We investigated via wind-tunnel experiments the role of the boundary conditions at the bed in the aeolian sand transport. We analyzed two different bed configurations: one with a sandy erodible bed and the other with a non-erodible bed. By using Particle Tracking Velocimetry technique (PTV), we characterized the saltation layer in both configurations and(More)
The properties of confined granular flows on a heap are studied through numerical simulations and experiments. We explain in details how such kind of flow can be numerically studied using periodic boundary conditions in the direction of the flow. The packing fraction and velocity profiles are found to be described by one length scale. The tracking of the(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 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)
Measurements indicate that the solid volume fraction on a sand ripple varies from random jammed packing at troughs to the minimum stable packing at crests. By relating variations of the solid volume fraction to those of the surface turbulent shear stress, a collisional model of reptation suggests a qualitative origin for these observations. Although the(More)