Bedload Transport. Part 1: Two-Phase Model and 3D Numerical Implementation

We have developed a three dimensional numerical model (Chauchat and Medale, 2010) based on the two-phase modeling having a Newtonian rheology for the fluid phase and Coulombtype friction for the particulate phase which has been developed by Ouriemi et al. (2009a) to study bedload transport in pipe flows. The governing equations are discretized by a finite element scheme and a penalisation method is introduced to cope with the incompressibility constraint. A regularisation technique is used to deal with the visco-plastic behaviour of the granular phase. We have performed three-dimensional computations for bedload transport in rectangular cross-section duct when the bed interface remains fixed. This numerical model which captures the complex coupling between the granular media and the fluid should enable a better understanding of the sediment transport mechanisms in these duct flows (Ouriemi et al., 2009b). The geometry corresponds to the one used in Pailha et al. (2011) where the authors investigate experimentally the behaviour of the flowing granular layer. The presented model and numerical results will be used for a detailed comparison in a near future.