Eur. Phys. J. E 16, 57-65 (2005)
DOI: 10.1140/epje/e2005-00007-0

A model of Barchan dunes including lateral shear stress

V. Schwämmle¹ and H.J. Herrmann<sup>1, 2

1</sup>  Institute for Computer Applications 1, University of Stuttgart, Pfaffenwaldring 27, 70569 Stuttgart, Germany
²  Departamento de Física, Universidade Federal do Ceará, 60455-970 Fortaleza, Brazil

veit@ica1.uni-stuttgart.de

(Received 23 April 2003 / Received in final form 11 November 2004 / Published online 31 January 2005)

Abstract
Barchan dunes are found where sand availability is low and wind direction quite constant. The two dimensional shear stress of the wind field and the sand movement by saltation and avalanches over a barchan dune are simulated. The model with one dimensional shear stress is extended including surface diffusion and lateral shear stress. The resulting final shape is compared to the results of the model with a one dimensional shear stress and confirmed by comparison to measurements. We found agreement and improvements with respect to the model with one dimensional shear stress. Additionally, a characteristic edge at the center of the windward side is discovered which is also observed for big barchans. Diffusion effects reduce this effect for small dunes.

PACS
47.54.+r - Pattern selection and formation.
45.70.-n - Granular systems.
92.10.Wa - Sediment transport.
92.60.Gn - Winds and their effects.
91.10.Jf - Topography; geometric observations.
92.40.Gc - Erosion and sedimentation.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2005