Abstract
A 2D RANS-VOF model is used to simulate the flow and sand transport for two different full-scale laboratory experiments: i) non-breaking waves over a horizontal sand bed (Schretlen et al., 2011) and ii) plunging breaking waves over a barred mobile bed profile (Van der Zanden et al., 2016). For the first time, the model is not only tested and validated in terms of water surface and outer flow hydrodynamics, but also in terms of wave boundary
 layer processes and sediment concentration patterns. It is shown that the model is capable of reproducing the outer flow (mean currents and turbulence patterns) as well as the spatial and temporal development of the wave boundary layer. The simulations of sediment concentration distributions across the breaking zone show the relevance of accounting for turbulence effects on computing suspended sediment pick-up from the bed.
Highlights
An accurate prediction of sediment transport is essential to properly simulate near-shore morphodynamics
The present study aims to overcome this gap by assessing the capability of a morphodynamic RANS-VOF model (Jacobsen et al, 2014; Jacobsen and Fredsøe, 2014) on simulating processes under non-breaking waves and under breaking waves conditions to be further used as a tool to investigate wave breaking effects on hydrodynamics and sediment transport over the whole water column
A RANS-VOF model has been validated for two full-scale laboratory experiments: first, for non-breaking waves propagating over a horizontal sand bed (Schretlen et al, 2011); second, plunging breaking waves over a mobile bed barred breaker bar profile (Van der Zanden et al, 2016)
Summary
An accurate prediction of sediment transport is essential to properly simulate near-shore morphodynamics. There is a general lack of understanding the effects of wave breaking hydrodynamics and turbulence on sediment transport The latter holds for the wave bottom boundary layer processes and near-bed transport (O(mm-cm) above the bed); a region which has not been considered in-depth during most previous experimental and numerical surf zone studies. 2D and 3D Boussinesq, RANS, LES and DNS models have been used to study water surface, flow and turbulence dynamics (among others Christensen et al, 2002; Zhao et al, 2004; Christensen, 2006; Torres-Freyermuth et al, 2007; Xie, 2012; Jacobsen et al, 2012; Brown et al, 2016; Zhou et al, 2017) under breaking waves They have been generally tested for small-scale breaking wave experiments, disregarding wave boundary layer processes and sediment transport.
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