Berlin 2015 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 12: Granular Matter / Contact Dynamics Part II

DY 12.5: Talk

Monday, March 16, 2015, 16:30–16:45, BH-N 128

Stabilty of Dune Fields — •Sven Auschra, Marc Lämmel, and Klaus Kroy — University of Leipzig, Institute for Theoretical Physics

Arid regions on Earth and Mars are often covered with vast assemblies of crescent-shaped sand dunes, so-called barchans. The observation that single barchans either shrink or grow indefinitely if fed by a constant homogeneous influx of sand [1], makes the existence and stability of such barchan fields a conundrum [2].

We investigate the steady-state configuration of consecutive barchan dunes interacting by wind-driven sand transport. Based on well-established equations for isolated dunes [1,3] we derive a coarse-grained description of the dominant pair interactions within a field. Sand supplied from the horns of windward dunes to its downwind neighbor initiates a complex response of its shape and mass. Based on a dimensionally reduced description justified by a closeby shape attractor, a fixed point equation for the mass balance of the fed dune is derived and analyzed for stable solutions. We provide evidence that this process is a good candidate for explaining the stabilization of barchan dunes in the field.

[1] Fischer, E., Cates, M. E., Kroy, K., 2008. Dynamic scaling of desert dunes. Phys. Rev. E 77, 031302.

[2] Duran, O. et al., 2011. Size distribution and structure of barchan dune fields. Nonlin. Processes Geophys. 69, 455-467.

[3] Kroy, K., Sauermann, G., Herrmann, H. J., 2002. Minimal Model for Sand Dunes. Phys. Rev. Lett. 88, 5.