Formation and development of a breaker bar under regular waves. Part 2: Sediment transport and morphology

摘要

In Part 2 of this work, the hydrodynamic model described in Part 1 is applied for the simulation of sediment transport and the associated morphological development of breaker bars. The sediment description is split into bed load and suspended load, and like the hydrodynamics the sediment transport is phase-resolved in order to get on- and offshore directed contributions to the sediment transport from phase lags between the suspended sediment and the hydrodynamics. First, the sediment transport over a morphologically fixed bed of a constant slope is considered, and the transport rates are discussed in terms of three dimensionless parameters: the surf similarity parameters (ξ_0) and two variants of Dean's parameter (Ω_D and Ω_(HK)). These cover the ranges ξ_0 ∈ [0.08,1.19], Ω_D ∈ [1.1, 27.7] and Ω_(HK) ∈ [0.01, 0.52]. Secondly, the morphological development of the cross-shore profile is considered, where the initial condition is a profile of constant slope. One reference simulation is discussed in detail and the morphological development due to changes in the hydrodynamic forcing (wave period, wave height, wave irregularity and a net cross-shore current) and in other properties (sediment size and beach slope) is discussed relative to the reference simulation. The coupling between sediment transport rate and morphology is analysed and discussed.