MODELLING OF 3D SEDIMENT TRANSPORT IN THE SURF ZONE

Berry Elfrink, Ida Broker, Rolf Deigaard, Erisk Asp Hansen, Peter Justesen

Abstract


The three-dimensional sediment transport in the surf zone has been investigated using two different approaches for modelling of the flow pattern. The first approach is based on the integrated momentum concept for the turbulent wave-current boundary layer, see Fredsoe (1984), the second approach is based on the k-model, as described in Deigaard et al. (1991). The k-model allows for a more consistent description of the time and space varying eddy viscosity than the integrated momentum approach, but demands considerably more computation effort. The driving forces are calculated according to the formulations of Deigaard et al. (1991) and Deigaard (1993). The model based on the integrated momentum equation is able to reproduce the details of the flow satisfactorily. The presence of a longshore current increases the turbulence near the bed. This results in a decreased offshore directed flow velocity near the bed and an increase in the sediment concentration. Comparisons with field measurements show good agreement.

Keywords


surf zone; sediment transport; 3D transport; transport modeling

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