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 Simulation of Regular Waves Interaction with Stepped Submerged Breakwaterin OpenFOAM
Watusiri Suwannarat, Susumu Araki
Department of Civil Engineering, Osaka University
Suita, Osaka, Japanfor wave attenuation. Mohamed (2014) studied the effects of using a
rectangular stepped submerged breakwater as a defense structure onshoreline. Three variable heights of thin plates were arranged asstepped slope of breakwater, which were compared between single anddouble rectangular vertical breakwater. This study was conducted on
physical model that was tested under regular wave. The experimental
results represented that using three rows of different plate’s heights is
better than using double rows and single row, respectively. Lokesha etal (2015) revealed the experimental investigations on wave
transmission at submerged breakwater with smooth and stepped slopes.
This study conducted in two-dimensional model, which was analyzedby the crest width and submergence height of structure. The conclusion
was revealed that stepped slope of submerged breakwater is able totransmit lower wave than smooth surface slope. An important geometry
factor in wave transmission coefficient is crest width, breakwater
submergence and slope roughness of submerged breakwater surface.
Lachmi et al (2017) investigated the wave attenuation performance offive submerged breakwaters that were made of multiple pipes indifferent configurations of physical modelling. The experimental
results showed that the front stepped slope of multiple pipes has been
fully optimized to enhance wave breaking and wave attenuation.
Ahmed and Taha (2019) investigated the hydrodynamic performance ofhalfpipe submerged breakwaters. Regular waves were generated innumerical model (FLOW 3D), which were used to focus on theinteraction of waves with different diameters of a precast in shape ofhalfpipe. A precast of halfpipe was set as a normal and inverse vertical
position in numerical wave flume. Moreover, two halfpipes in ahorizontal (H-shape) and vertical (X-shape) position were also tested inthis study. The numerical results showed that geometry of submerged
breakwater considerably effects to the ability of wave energy
dissipation. The hydrodynamic efficiency of halfpipe in normal
position is able to provide more energy dissipation than inverse
position. In case of two halfpipes, X-shape is better than H-shape interms of wave energy attenuation. Sarhan (2020) investigated theefficiency of stepped submerged breakwater with and without slotted.
This study was carried out on experimental model that was conducted

ABSTRACTThe effects of stepped slope on submerged breakwater are investigated
for the efficiency of wave energy dissipation. This paper focuses on
stepped submerged breakwater with different step sizes and crest
widths, which are carried out on numerical simulation (OpenFOAM®).
Regular waves are used to study the interaction of waves with structure.
The performance of wave dissipation is identified in terms of reflection
coefficient (Kr), transmission coefficient (Kt) and wave energy
dissipation (Kd). Moreover, the behavior of fluid flow around a stepped
submerged breakwater is illustrated in terms of turbulent kineticenergy. The numerical results are concluded to compare the efficiencyof wave dissipation based on the geometries of stepped submerged
breakwater.

KEY WORDS: stepped submerged breakwater; wave reflection
coefficient; wave transmission coefficient; wave energy dissipation;
turbulent kinetic energy; OpenFOAM; OlaFlow

INTRODUCTION
Breakwaters play an important role in coastal protection which areconstructed as wave damage prevention and beach control devices. In
last few decades, submerged breakwaters have been increasingly used
as a potential coastal protection because of the desirable consequence.
This special type of breakwater is built with their crest submerged
under water surface. Based on this advantage, submerged breakwaters
provide the exchange of wave flow between onshore and offshore,
which support to improve water quality nearby shoreline. Moreover,beside a significant amount of wave reflection and transmission, thistype of breakwater also preserves the ecosystem and maintains pleasing
esthetics, which exactly supports to tourism industry in coastal area.
Although submerged breakwaters are not as powerful as emergedbreakwaters, but these advantages advocate to widely construct inbeach areas. To overcome this problem, many researchers attempt todevelop and find out the productive shapes of submerged breakwater

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