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

CFD ANALYSIS OF WIND EFFECT ON WAVE OVERTOPPINGAngela Di Leo1, Mariano Buccino 2, Fabio Dentale 1, Eugenio Pugliese Carratelli 1
1 Department of Civil Engineering, University of Salerno, Fisciano, Salerno, Italy
2 Department of Civil, Architectural and Environmental Engineering, University of Naples “Federico II” Napoli, Italy

wind qwind, and the same discharge without the wind q, thus fwind =qwind/q.
It is found that fwind varies according to q, and, and as stated above, isnormally higher when q is small, and becomes closer to 1 for high values
of q.

ABSTRACT
It is widely assumed that onshore winds significantly increase runup andovertopping; several recent research results have indeed shown that thiseffect cannot be neglected. The effects of the wind and of the spraygeneration on the overflow phenomenon thus seem to be important in thedesign of seawalls, even though they are difficult to quantify throughhydraulic model experiments due to the problem of wind scaling.
The use of a numerical model overcomes the limits of scale effects inexperimental tests, thus making it possible to consider the action of windinduced shear stress on the increase of the up-rushing jet near the wall.
The present work presents a numerical wind stress model that takes into
account such action on wave overtopping.

KEY WORDS:

Physical models have been conducted by Pullen et al. (2009) and De
Waal et al. (1996), who both experienced similar challenges with regardsto scaling wind, as the surface tension, viscosity and droplet sizes are thesame for both the prototype and model.
The problem of wind scaling is indeed a difficult task, and the use of
Froude scale in physical model, where the gravity is the predominantfactor, is incorrect because the spray phenomenon is turbulent and should
be modelled with Reynold’s scaling.
Wind affects the overtopping discharge through two actions: wave
deformation of the water surface in front of the seawall, and theconvection of the water particles behind the seawall (Masami Kiku andKoji Kawasaki, 2014). De Wall et al. 1996, clarified that the wind causes
the overtopping of the part of the breaker spray which would have fallenback into the sea in a situation without wind.

wave overtopping; wind effect; CFD; numericalmodel.

INTRODUCTION AND LITERATURE REVIEWThe influence of wind on overtopping can be described as consequenceof strong onshore wind pushing cause part of the upwards projectedwater to be transported landwards over the crest.
Some research studies have suggested that the effects of onshore winds
on large overtopping discharges (so called “green water”) are relatively
small; on the contrary when the overtopping is below q = 1 l/s per m, it
might increase by up to 4 times under strong winds (EurOtop Manual2018). It is therefore widely assumed that onshore winds might becomea relevant design problem for seawalls (Ward et al., 1996; De Waal et al.
1996). Such effects are thus important, but they are difficult to quantify
by making use of physical hydraulic models.

De Waal et al. (1996) took an innovative approach to the problem,
seeking to quantify the maximum possible wind transport effect by usinga paddle wheel to “push” all water that reached the height of the crest
over the wall. They find that wind causes an increase of the mean
overtopping discharge not larger than 3.2 (qwind, max = 3.2 q)
De Rouck et al. 2005, using the results from small scale model test andthe output from a Neural Network for wave overtopping predictions,
propose a procedure to take into account wind effects.
A factor fwind between 1 (for q=10 l/s/m) and 4 (for q 0.01 l/s/m) isproposed.
Pullen et al. (2009), in order to study the effects of the wind in thelaboratory, placed 4 fans in front of the seawall in a manner analogous
to the paddle wheel of De Wall et al. 1996. By making use of both field

In order to quantify the influence of the wind, a factor fwind is defined as
the ratio between the overtopping discharge including the effect of the2692