Jo, Y.J. and Cho, Y.J., 2023. How the beach restoration process, driven by bound mode infra-gravity waves underlying swells in a mild sea, is affected by the presence of LCB: A numerical study. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 618-622. Charlotte (North Carolina), ISSN 0749-0208.
This study aims to numerically investigate the impact of Low Crested Breakwater [LCB] on the beach restoration process driven by bound mode infra-gravity waves beneath swells in a mild sea. In doing so, the authors also delve into the evolving extent of boundedness of infra-gravity waves to a wave packet during shoaling. Additionally, the authors explore the effects of this evolution on sediment transport. The infra-gravity waves were extracted from a numerically simulated wave field using the Empirical Mode Decomposition method. Numerical results reveal a transition in the cross-correlation between a wave packet and infra-gravity waves from negative to positive during shoaling, especially when the phase of infra-gravity waves is initially shifted by as much as π. These correlation patterns align well with the wave data acquired by Abdelrahman and Thornton. Furthermore, the degree of boundedness of infra-gravity waves to a wave packet has a significant impact on the sediment transport rate. When fully phase-locked, a substantial amount of sand, in the form of bedload, escapes offshore through the open inlet between LCB. Approximately 5 × 10–3m3/m of sand exits the inner zone of LCB per unit amplitude modulation period of a wave packet. Conversely, with a phase shift of π, the primary sediment transport mode at the open inlet between LCB becomes bedload. Sand migrating toward the shore balances with offshore-directed sediment transport, marking a departure from previous studies focused on monochromatic waves only.
