Bedload Transport on Steep Slopes with Coupled Modeling Based on the Discrete Element Method
Abstract:After more than a century of research, a clear understanding of the physical processes involved in sediment transport problems is still lacking. In particular, modeling of intergranular interactions and fluid-particle interactions in bedload transport need to be improved. In this contribution, we propose a simple numerical model coupling a Discrete Element Method (DEM) for the grain dynamics with a simple 1D vertical fluid phase model inspired from the two-phase approach  in order to contribute to this open question. The Reynolds stress is parameterized by a mixing length model which depends on the integral of the grain volume fraction. The coupling between the grains and the fluid phase is essentially achieved through buoyancy and drag forces. The open source DEM code Yade  is used with a linear spring-dashpot contact law that allows the description of the behavior of the particles from the quasi-static to the dynamical state. The model is compared with classical results  and with particle-scale experimental results obtained in the quasi-2D flume at IRSTEA, Grenoble . We discuss the closures of the model and the sensitivity to the different physical and numerical parameters.
 Revil-Baudard, T. and J. Chauchat. A two-phase model for sheet flow regime based on dense granular flow rheology. Journal of Geophysical Research: Oceans, 118(2):619–634, 2013.
 Šmilauer V. , E. Catalano, B. Chareyre, S. Dorofeenko, J. Duriez, A. Gladky, J. Kozicki, C . Modenese, L. Scholtès, L. Sibille, J. Str.nský, and K. Thoeni. Yade Documentation (V. Šmilauer, ed.), The Yade Project, 1st ed., http://yade-dem.org/doc/., 2010.
 Meyer-Peter, E. and R. Müller. Formulas for bed-load transport. In Proc. 2nd Meeting, pages 39–64. IAHR, 1948.
 Frey, P. Particle velocity and concentration profiles in bedload experiments on a steep slope. Earth Surface Processes and Landforms, 39(5):646–655, 2014.