The linear stability analysis of equations governing the evolution of a flat sand bed submitted to a shearing flow predicts that the wavelength λ at which the bed destabilises to form dunes should scale with the drag length Ldrag = ρs ρf d. We tested this scaling law using measurements performed in water (subaqueous ripples), in air (aeolian dunes) and in the CO2 martian atmosphere (martian dun...

Results from a three-year study are presented that integrate field work (in Israel), physical modeling (wind-tunnel testing at UC Davis), and numerical solutions of grain trajectories to model and explain sand transport over a climbing dune. Field grain-size analyses of surfaceand saltation-trap materials taken along various positions of the slope suggest that only smaller particles (< 230 pm i...

Aeolian sand beds exhibit regular patterns of ripples resulting from the interaction between topography and sediment transport. Their characteristics have been so far related to reptation transport caused by the impacts on the ground of grains entrained by the wind into saltation. By means of direct numerical simulations of grains interacting with a wind flow, we show that the instability turns...

Predicting solid particle transport in the lowest parts of atmosphere is a major issue for man-made obstacles semi-arid regions. Here, we investigate effects on saltation, square ground with different spacings. The aerodynamic field determined by large eddy simulations coupled an immersed boundary method obstacles. Solid particles are tracked Lagrangian approach. Take-off and rebound models int...

We investigated the influence of motion context on tactile localization, using a paradigm similar to the cutaneous rabbit or sensory saltation (Geldard FA, Sherrick CE. Science 178: 178-179, 1972). In one of its forms, the rabbit stimulus consists of a tap in one location quickly followed by another tap elsewhere, creating the illusion that the two taps are near each other. Instead of taps, we ...

Semiarid landscapes are characterized by vegetated surfaces. Understanding the impact of vegetation on aeolian soil erosion is important for reducing soil erosion or limiting crop damage through abrasion or burial. In the present study, a saltation model fully coupled with a large-eddy simulation airflow model is extended to vegetated landscapes. From this model, the sensitivity of sand erosion...

in our present research, we focus on the modeling of airflow related to natural disasters, such assand accumulation, with urban form studies. the objective is to find which urban form can promote sand passing andreduce as much as possible stagnation of sand in the building area (streets, alleys, etc.). the urban form design will bediscussed through the simulation of airflow by using computation...