Modeling sand transport by strong currents and waves using DPM



Persons involved:

Ir. Fenneke Sterlini (PhD student)

Jan Ribberink (WEM)

Martin van der Hoef (FCRE).




2009 – 2012


Understanding, and hence predicting the transport of sand induced by shoaling short water waves in near shore areas is still difficult, due to the complexity of the sediment-water interactions occurring in the wave boundary layer near the sea bed. For practical applications, empirical relations (sand transport formulas) are available, however both the range of validity and the accuracy of these relations is limited. Models taking into account the hydrodynamics of the system (such as the Reynolds-Averaged Navier-Stokes (RANS) models and continuum two-phase flow models) are able to explain the observed dynamics to some extent but their performance is still insufficient to replace the empirical sand transport formulas.

In this project, we propose to model sediment-water interactions at a more fundamental level, where the sand particles are treated as discrete entities (in the first instance, modelled by simple spheres). In this discrete particle (DP) model, the fluid flow is modelled by traditional CFD methods, whereas for the solid phase granular dynamics is used. Both phases interact via empirical drag force relations. The advantage of a DP model, based on particles is that the solid-solid interaction is accurately modelled, and also it opens the possibility to study non-uniform particles (mixtures of different sizes) and the effect of particle shape. Finally, the DP models are ideally suited to test (and improve) the closures that are used in the continuum models. Experimental data will be used to test the predictive capabilities of the discrete particle model.