Non-aeolian sand ripplesJ. F. Boudet, Y. Amarouchene, B. Bonnier and H. Kellay
CPMOH (UMR5798), U. Bordeaux 1 - 351 cours de la Libération 33405 Talence, France
received 1 September 2004; accepted in final form 24 November 2004
published online 24 December 2004
By examining the initial stages of the impact of a granular jet on a flat horizontal solid surface we evidenced the existence of oscillatory sand fronts. These oscillations give rise to a novel mechanism for the formation of ripples on sand surfaces. We here show that as the front advances, its slope changes periodically in time, leaving behind a succession of surface elevations and depressions. A key feature of these oscillations is the interplay between the deposition of mobile sand and the avalanching of the static parts giving rise to a remarkable self-regulating system. These features come out naturally from a simplified version of recently proposed models for the dynamics of sand piles.
45.70.-n - Granular systems.
45.70.Ht - Avalanches.
45.70.Qj - Pattern formation.
© EDP Sciences 2005