Linear stability analysis of transverse dunes

Abstract

Sand-moving winds blowing from a constant direction in an area of high sand availability form transverse dunes, which have a fixed profile in the direction orthogonal to the wind. Here we show, by means of a linear stability analysis, that transverse dunes are intrinsically unstable. Any along-axis perturbation on a transverse dune amplify in the course of dune migration due to the combined effect of two main factors, namely: the lateral transport through avalanches along the dune's slip-face, and the scaling of dune migration velocity with the inverse of the dune height. Our calculations provide a quantitative explanation for recent observations from experiments and numerical simulations, which showed that transverse dunes moving on the bedrock cannot exist in a stable form and decay into a chain of crescent-shaped barchans.

8 pages, 4 figures

References in corpus (3)

• Transverse instability of dunes
• Profile measurement and simulation of a transverse dune field in the Lençóis Maranhenses
• Calculation of the separation streamlines of barchans and transverse dunes

Cited by in corpus (4)

• The physics of wind-blown sand and dust
• The formation and migration of sand ripples in closed conduits: experiments with turbulent water flows
• Velocity fields of a bed-load layer under a turbulent liquid flow
• Stability of transverse dunes against perturbations; a theoretical study using dune skeleton model