Gaps in understanding of sedimentary bedforms in the ancient, the present, the extraterrestrial and the kitchen
Kleinhans, M.G. (2013). Gaps in understanding of sedimentary bedforms in the ancient, the present, the extraterrestrial and the kitchen, in: Van Lancker, V. et al. (Ed.) MARID 2013: Fourth International Conference on Marine and River Dune Dynamics. Bruges, Belgium, 15-17 April 2013. VLIZ Special Publication, 65: pp. 1-4 In: Van Lancker, V.; Garlan, T. (Ed.) (2013). MARID 2013: Fourth International Conference on Marine and River Dune Dynamics. Bruges, Belgium, 15-17 April 2013. VLIZ Special Publication, 65. Royal Belgian Institute of Natural Sciences/SHOM/Flanders Marine Institute (VLIZ): Oostende. ISBN 978-2-11-128352-7. 338 pp., more In: VLIZ Special Publication. Vlaams Instituut voor de Zee (VLIZ): Oostende. ISSN 1377-0950, more |  |
| Abstract | Much is known about bedforms, but a number of critical gaps in understanding remain. These gaps become clear when present understanding is extrapolated to extreme materials, conditions or environments. Advanced physicsbased modelling demonstrates that dunes and upper-stage plane bed are predictable from the laws of physics, but may be sensitive to constitutive relations for flow and particle friction and sediment transport. Furthermore the question whether current ripples and dunes are distinct forms or the same forms with different sizes remains unanswered. Empirical work and experiments shows that a zoo of phenomena and bedforms emerge in cohesive sediments or sand-gravel mixtures, in hyperconcentrated flows and turbidity currents, showing that mixtures of particle sizes with different weight or other properties require basic exploration. Finally, the angle of repose is the most basic characteristic of sediment relevant for inter-particle friction and the steep lee side of bedforms, but prediction from physics remains poorly understood as demonstrated by measurements in lower gravity. The above phenomena arise because of three general mechanisms that can understood: 1) the laminar to turbulent flow transition, 2) friction between particles and 3) cohesive forces. |
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