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| Titel |
Pattern formation in granular binary mixtures under shear flow |
| VerfasserIn |
Xin Gao, Clement Narteau, Olivier Rozier |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077499
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| Zusammenfassung |
| We study numerically the formation and evolution of bed forms using a binary granular
mixture. The two types of particles may have different dynamic properties and angle of
repose. We associate these changes to two different grain sizes, the so-called coarse and thin
particles. Our computation are based on a real-space cellular automaton that combines a
model of sediment transport with a lattice-gas cellular automaton. Thus, we implement
the permanent feedbacks between fluid flow and topography. Keeping constant
the strength of the flow, we explore a parameter-space by varying the size of the
coarse particles and their proportion within the bed. As a result of avalanches and
sediment transport, we systematically find regions of segregation and stratification. In a
vast majority of cases, we also observe the formation of an armoring layer mainly
composed of coarse particles. Its depth is mainly controlled by the proportion of
coarse grains and not by the size of these larger particles. When there is a larger
proportion of thin particles, transverse dunes develop on the top of the armoring
layer. As this proportion decreases, we may observe barchans or even no clear bed
forms. We conclude that the main control parameter for dune pattern formation is the
thin sediment availability. Finally, we discuss the processes responsible for the
formation of the armoring layer and show how it controls the overall sediment
transport. |
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