Abstract
Numerical experiments are carried out to simulate the development and migration of a barchan dune starting with a conical pile of sand. Such an experiment is done in three steps: (1) computation of the steady-state wind field over and around a barchan using the numerical meso-scale simulation model FITNAH, whereby the horizontal variation of the friction velocity is also calculated; (2) computation of the sand transport using the friction velocity in the transport formula by Lettau and Lettau (1978); (3) computation of the erosion and deposition rates as the divergence of the sand transport, where a special treatment is used for the slip-face of the barchan dune. Adding these rates to the height field leads to a different shape of the dune after a time step δt h . Then this procedure has to be repeated for the next time step δt h .
The results are in good agreement with observations: the initial pile of sand develops wings (‘horns’) and a slip-face between them. In addition, flow separation over the lee-side can be simulated. Finally, the tendency to form a barchan in equilibrium is considered.
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Wippermann, F.K., Gross, G. The wind-induced shaping and migration of an isolated dune: A numerical experiment. Boundary-Layer Meteorol 36, 319–334 (1986). https://doi.org/10.1007/BF00118335
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DOI: https://doi.org/10.1007/BF00118335