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| Titel |
Dunes morphologies and superimposed bedforms in a cellular automaton dune model |
| VerfasserIn |
D. Zhang, C. Narteau, O. Rozier, P. Claudin |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028674
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| Zusammenfassung |
| We use a new 3D cellular automaton model for bedform dynamics in which individual
physical processes such as erosion, deposition and transport are implemented by nearest
neighbor interactions and a time-dependent stochastic process. Simultaneously, a lattice gas
cellular automaton model is used to compute the flow and quantify the bed shear stress on the
topography. Local erosion rates are taken proportional to the shear stress in such a way that
there is a complete feedback mechanism between flow and bedform dynamics. In the
numerical simulations of dune fields, we observe the formation and the evolution of barchan,
transverse, longitudinal and star dunes. For all these types of dunes, we observe the
emergence of superimposed bedforms when dunes are large enough. Then, we use the
same model under different initial conditions, and we perform the linear stability
analysis of a flat sand bed disturbed by a small sinusoidal perturbation. Comparing the
most unstable wavelength in the model with the characteristic size of secondary
bedforms in nature, we determine the length and time scales of our cellular automaton
model. Thus, we establish a link between discrete and continuous approaches and
open new perspectives for modeling and quantification of complex patterns in dune
fields. |
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