Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Wave overtopping at a vertical seawall by Boussinesq modelingSara Tuozzo, Margherita Carmen Ciccaglione, Mariano Buccino, Giuseppe Ascione, Mario Calabrese
Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II.
Naples, Italyet al., 2017; Buccino et al., 2019a,b), turning out to be a reliable tool
showing good agreement with physical model results. However, asignificant computational cost negatively impacts on the attractivenessof these models. More computationally efficient, Non-Linear Shallow
Water equations (NLSW) models have also been recently adopted for
estimation of wave overtopping discharge, showing satisfactory
performances (Tuan et al, 2012; Suzuki et al., 2017). In this framework,
the Boussinesq-type models (BTMs) should be an optimal tool available
to coastal engineering community, due both to the ability to represent all
main physical phenomena and numerical cheapness (Brocchini, 2013).
Despite this, only a few researchers employed BTMs to deal with wave
overtopping. As supposed by Tonelli and Petti (2013), this may be due
to difficulty of traditional Boussinesq models to intrinsically deal withmoving shorelines, since they used to resort to artificial algorithms (e.g.
Madsen et al., 1997; Lynett et al., 2002). Nonetheless, more recently
scientific improvements overcame this weakness guaranteeing theaccurate modelling of wave overtopping by means of BTMs (Tonelli andPetti,2013; Lynett et al., 2010).
The present paper aims to analyse the wave overtopping prediction
ability of the open source Boussinesq model, Celeris (Tavakkol andLynett, 2017). Specifically, we investigate wave overtopping at a verticalseawall with shallow foreshore validating Celeris with a series of random
wave physical model tests carried out at the University of Naples
Federico II, Italy.

ABSTRACT
Numerical models may represent a useful tool to estimate wave
overtopping discharge. However, so far there is still little available
literature on numerical modeling, especially on Boussinesq modeling.
The paper analyses the ability of a BTM, Celeris, to predict wave
overtopping at a vertical seawall with shallow foreshore, comparing
numerical outcomes with physical results of an experimental campaign
carried out at the University of Naples Federico II, Italy. The validation
has shown that the model needs to be calibrated to avoid overestimationand obtain a reliable tool. In this paper we opted to calibrate the Manningcoefficient, which acts as an additional dissipative term to limit
overestimation and achieve accurate assessments.

KEY WORDS: Wave overtopping; Boussinesq-type model; Celeris.
INTRODUCTIONWave overtopping is one of the main issue affecting coastal areas,
especially in light of the ongoing sea level rise. It is indeed one of themost intensively researched topics of coastal engineering. A reliable
estimate of wave overtopping is an essential prerequisite for assessing
the risk of coastal inundation and designing new coastal defences against
flooding. Various predictive tools are available for planning, such as
empirical formulae and physical model studies, machine learningtechniques (Artificial Neural Network – ANN), and numerical models.
Although the empirical-based methods are the most researched, as
evidenced by the wide body of literature (e.g. TAW, 2002, and EurOTop
Manual, 2018), they are based on laboratory and field experiments; theirvalidity is limited to the hydrodynamic conditions and geometricalcharacteristics studied, while out-of-range use undermines theirreliability. On the other hand, numerical models have increasingly been
employed to estimate wave overtopping of coastal structures. Since they
overcome limitations tied to empirical methods, numerical models may
be a supplementary tool useful both for design purposes and flooding
risk assessment.
In the last years, the literature mostly focuses on numerical models basedon the Reynolds averaged Navier–Stokes equations (RANS). They havebeen received an increasing amount of attention concerning wave
overtopping modelling (Losada et al., 2008; Ingram et al., 2009; Akbari

NUMERICAL MODEL
Celeris is an open source Boussinesq-type model developed by theCoastal Engineering Group and the Tsunami Research Center ofUniversity of Southern California (Tavakkol and Lynett, 2017).

Governing equations
Celeris is a phase-resolved model based on the extended Boussinesq
equations derived by Madsen and Sørensen (1992), formulated inconservative form as:2699