Author(s): Huabin Shi; Shuo Li
Linked Author(s): Huabin Shi
Keywords: Beach erosion; Dam-break swash; Two-phase SPH model; Sediment transport; Sheet flow
Abstract: The erosion of sandy beach by single dam-break swash events is simulated with a two-phase SPH model GPUSPH-MIDSEPT (Shi et al., 2017; 2019; 2021; Guan & Shi, 2023). The well-documented model is further validated in laboratory experiments of dam-break swash on saturated sandy beaches. The temporal and spatial variations of water depth, velocity, bed shear stress, topography, and sediment transport flux are well reproduced by the model and more details other than measured are provided (Figure 1). During a single dam-break swash, the uprush and the backwash flows show significantly difference in the profiles of depth-averaged velocity and bed shear stress. The uprush flow is generally quicker than the backwash. The spatial distribution of bed shear stress in the uprush flow is notably non-uniform, with higher values at the bore front (Figure 2a). Comparatively, in the backwash flow, the bed shear stress is somewhat uniformly distributed in a wide range of the beach (Figure 2b). On movable beaches, the relations between the thickness of sheet flow layer and the sediment transport rate with bed shear stress are extensively and quantitatively investigated. There are noteworthy differences in the quantitative sediment-stress relations during uprush and downwash flows, which may lead to seaward net transport of sediment in the swash zone. Moreover, the dominant forces for beach erosion during different stages are thoroughly examined.
Year: 2024