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Open AccessArticle

On Ripples—A Boundary Layer-Theoretical Definition

by 1,2,* and 3
1
Z & P—Prof. Zanke and Partner, Ackerstr. 21, D-30826 Garbsen, Hannover, Germany
2
TU Darmstadt, D-64289 Darmstadt, Germany
3
BGS-ITE, Pfungstaedter Straße 20, D-64297 Darmstadt, Germany
*
Author to whom correspondence should be addressed.
Academic Editor: Sameh Kantoush
Water 2021, 13(7), 892; https://doi.org/10.3390/w13070892
Received: 26 January 2021 / Revised: 10 March 2021 / Accepted: 13 March 2021 / Published: 24 March 2021
(This article belongs to the Special Issue Sediment Transport and River Morphology)
Once the first initial ripples have developed, they form according to the actual flow forces and sediment properties. In this paper, a semianalytical approach to determine the length of the developed ripples is presented. The theory assumes initial disturbances at the bed surface and corresponding flow separations resulting from an individual respective boundary layer. What causes the initial rhythmic perturbations is not the subject of this paper. Based on boundary layer theory, this approach explains a possible physical background for the existence and length of developed ripples in cohesion-free sediments. At the same time, the approach provides a distinction from dunes: ripples are sand waves affected by a viscous sublayer, and dunes are sand waves where this is not the case. Applications to Earth, Mars, and Titan are shown. View Full-Text
Keywords: sediment transport; ripples; dunes; bed forms; Mars; Titan sediment transport; ripples; dunes; bed forms; Mars; Titan
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MDPI and ACS Style

Zanke, U.; Roland, A. On Ripples—A Boundary Layer-Theoretical Definition. Water 2021, 13, 892. https://doi.org/10.3390/w13070892

AMA Style

Zanke U, Roland A. On Ripples—A Boundary Layer-Theoretical Definition. Water. 2021; 13(7):892. https://doi.org/10.3390/w13070892

Chicago/Turabian Style

Zanke, Ulrich; Roland, Aron. 2021. "On Ripples—A Boundary Layer-Theoretical Definition" Water 13, no. 7: 892. https://doi.org/10.3390/w13070892

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