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

Numerical Study on Breaking Waves Interaction with Vertical Wall attached with Recurved Parapet
Songtao Chen1, Qingjie Meng2, Decheng Wan1*1

Computational Marine Hydrodynamics Lab (CMHL), School of Naval Architecture, Ocean and Civil Engineering,
Shanghai Jiao Tong University, Shanghai, China
2Wuhan Second Ship Design and Research Institute, Wuhan, China*Corresponding author

more attention recently. Kortenhaus et al. (2002, 2003) highlighted theeffectiveness of the recurves and parapets in wave overtopping throughabundant experimental data collected in the wave flume of theLeichtweiβ-Institute. Nevertheless, they pointed out that their existences
may increase the wave loadings on the vertical wall. Ravindar et al.
(2019) conducted large-scale (1:1) experiments to characterize theimpact pressure under different wave breaking conditions at the Coastal
Research Centre (FZK), Germany. According to their classification, it
can be divided into three conditions: slightly breaking waves (SBW),breaking waves with small air trap (BWSAT), and breaking waves withlarge air trap (BWLAT). In addition, they reported the significant effectof the entrained air on the impact pressure. On this basis, Ravindar et al.
(2021a, b) carried out small-scale (1:8) experiments in the Departmentof Ocean Engineering at the Indian Institute of Technology Madras,
Chennai, Tamil Nadu, India. They analyzed the scale effects andproposed a combined Cuomo-Froude method for scaling up the impact
pressure of small-scale results. Besides, they also discussed the impact
pressure and forces of different types of parapets under the aboveclassified wave breaking conditions.

ABSTRACTThis paper numerically investigates breaking waves interaction with avertical wall attached with a recurved parapet in 1:8 model scale. The inhouse CFD solver naoe-FOAM-SJTU based on the open source platform
OpenFOAM is used to perform the simulation. For wave generation, anovel generating-absorbing boundary condition (GABC) is adopted toreplace the time-consuming moving boundary wavemaker. A geometricvolume-of-fluid (VOF) method based on piecewise-linear interface
calculation (PLIC) is incorporated in the present numerical model tocapture the sharp interface and improve the accuracy of the predicted
impact pressure. The time histories of the wave elevation and pressure ateach probe are presented as well as the frequency analysis. In addition,
the evolutions of free surface and pressure distribution are further
provided to achieve a better understanding of this complex wavestructure interaction issue.
KEY WORDS: breaking waves; recurved parapet; naoe-FOAM-SJTU;
generating-absorbing boundary condition (GABC); geometric VOF
methodConsidering the scale effect and the possible entrained air pocket, more
and more scholars have adopted various numerical approaches toinvestigate the detailed behaviors of this problem. Castellino et al.
(2018a, b) used the single-phase solver IH2VOF and the two-phasesolver IHFOAM to conduct a series of two-dimensional simulations of avertical breakwater with a recurved parapet under non-breaking waves.
They identified an impulsive phenomenon referred to as “confined-crestimpact” and further performed a sensitivity study on the parameters of
the recurved parapet. Liu et al. (2019) used a two-phase compressible
CFD solver with the Ghost Fluid Method (GFM) and a free surface
turbulence model to explore the violent breaking wave impacts on a
vertical wall. In their solver, the air compressibility was taken into
account, thus being more physical under wave breaking conditions.
Among four considered breaking conditions, they observed themaximum wave forces appear in the “flip-through” and “large air pocket”
cases. Molines et al. (2020) numerically investigated the influence ofparapets on crown walls of mound breakwaters with parapets based on
OpenFOAM. Consistent with the previous studies, the dimensionless

INTRODUCTION
Vertical breakwaters are typical coastal structures intended to reduce theeffects of incoming waves, especially in extreme sea conditions. In
practical design, wave overtopping has been a significant issue ofsustained concern for decades. Among the various solutions, a parapet
fixed on the top of the vertical wall has been proven effective bydeflecting back the up-rushing water seawards. However, according to
the previous studies, the shape and parameters of the parapet will
significantly influence the impact force and pressure compared with theoriginal vertical wall. In order to provide guidelines to predict the wave
impact and wave loading, it is necessary to systematically investigate thevariations under different wave conditions, including non-breaking andbroken waves.
As a representative shape, the recurved parapet has gradually attracted

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