Minimal size of a barchan dune

Abstract

Barchans are dunes of high mobility which have a crescent shape and propagate under conditions of unidirectional wind. However, sand dunes only appear above a critical size, which scales with the saturation distance of the sand flux [P. Hersen, S. Douady, and B. Andreotti, Phys. Rev. Lett. {\bf{89,}} 264301 (2002); B. Andreotti, P. Claudin, and S. Douady, Eur. Phys. J. B {\bf{28,}} 321 (2002); G. Sauermann, K. Kroy, and H. J. Herrmann, Phys. Rev. E {\bf{64,}} 31305 (2001)]. It has been suggested by P. Hersen, S. Douady, and B. Andreotti, Phys. Rev. Lett. {\bf{89,}} 264301 (2002) that this flux fetch distance is itself constant. Indeed, this could not explain the proto size of barchan dunes, which often occur in coastal areas of high litoral drift, and the scale of dunes on Mars. In the present work, we show from three dimensional calculations of sand transport that the size and the shape of the minimal barchan dune depend on the wind friction speed and the sand flux on the area between dunes in a field. Our results explain the common appearance of barchans a few tens of centimeter high which are observed along coasts. Furthermore, we find that the rate at which grains enter saltation on Mars is one order of magnitude higher than on Earth, and is relevant to correctly obtain the minimal dune size on Mars.

11 pages, 10 figures

References in corpus (6)

• A Continuum Saltation Model for Sand Dunes
• Selection of dune shapes and velocities. Part 1: Dynamics of sand, wind and barchans
• Minimal model for aeolian sand dunes
• Aeolian transport layer
• Profile measurement and simulation of a transverse dune field in the Lençóis Maranhenses
• On the shape of barchan dunes

Cited by in corpus (21)

• The physics of wind-blown sand and dust
• Numerical simulation of turbulent sediment transport, from bed load to saltation
• Dune formation on the present Mars
• Flux saturation length of sediment transport
• The apparent roughness of a sand surface blown by wind from an analytical model of saltation
• A two-species continuum model for aeolian sand transport
• Saltation transport on Mars
• A comprehensive picture for binary interactions of subaqueous barchans
• Analytical model for flux saturation in sediment transport
• Role of transverse displacements in the formation of subaqueous barchan dunes
• Discrete Element Method simulations of the saturation of aeolian sand transport
• Birth of a subaqueous barchan dune
• Direct validation of dune instability theory
• Comment on "Minimal size of a barchan dune"
• Analytical mesoscale modeling of aeolian sand transport
• Reproducing size distributions of swarms of barchan dunes on Mars and Earth using a mean-field model
• Reply to "Comment on `Minimal size of a barchan dune' "
• Velocity fields of a bed-load layer under a turbulent liquid flow
• Particle dynamics of a cartoon dune
• Evolving dunes under flow reversals: from an initial heap toward an inverted dune
• Measurements of the aeolian sand transport saturation length