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Numerical Model of Wave-Induced Scour Effects Around Coastal Structures

Author(s): Pilar Diaz-Carrasco; Sergio Croquer; Vahid Tamimi; Sebastien Poncet; Jay Lacey; Ioan Nistor

Linked Author(s): Sergio Croquer, Ioan Nistor

Keywords: CFD simulations; OpenFOAM model; Wave-structure interaction; Sediment transport; Scour effect

Abstract: Coastal structures such as seawalls and breakwaters provide protection from the effects of the sea and create the conditions for economic growth in a coastal environment. These maritime structures also protect ports and coasts against the marine dynamics and its function will be even more important in the upcoming years due to sea level rise and coastal regression as a result of global warming (Del-Rosal-Salido et al., 2019). However, the presence of the structure changes the flow patterns in its immediate neighborhood, such as wave reflection and breaking, turbulence and liquefaction (Sumer and Fredsøe, 2002). These processes increase the local sediment transport and thus lead to one of the greatest problems for the seabed and for the stability of the structure: the scour effects. Hence, the main objective of this work is to develop a mathematical integrated model to investigate the scour seabed response in the vicinity of a maritime structure, using the open source package OpenFOAM (OpenCFD, 2014). For that, the wave-structure-seabed response interaction is modelled following a decoupled solid and flow responses implementation (Zhao and Jeng, 2015; Li et al., 2020): wave-structure module and seabed module. The wave-structure module is based on the Volume-Averaged/Reynolds Averaged Navier–Stokes (VARANS) equations, while the consolidation equations of Biot (Biot, 1941) is used to govern the seabed module. The wave-induced soil response variables (soil displacements, stresses and pore pressures) are considered in the seabed module, as well as the effect of structure weight on the initial consolidation status (effective normal stresses). The influence of turbulence fluctuations on the mean flow with respect to the complicated interaction between waves, seabed and maritime structure are obtained through the turbulence model of Menter (Menter, 2003). The olaFlow suite (Higuera, 2017) provides the wave generation and reflection control at the domain boundaries. In the congress, the results of the seabed response around (1) an impermeable seawall and (2) a permeable rubble-mound breakwater will be presented. The model will be validated with experimental data from the literature (Tsai et al., 1995, 2009; Fausset et al., 2017) and will be compared with the numerical method used by Ahmad et al. (2019) based on the sediment transport equations (van Rijn, 1984a,b) and the Exner’s formula for the seabed level.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022200

Year: 2022

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