Numerical simulation for overtopping discharge on tetrapod breakwater

An armour unit such as Tetrapod is widely used as breakwater to defend a coastline from erosion. Tetrapod is madeby reinforced concrete in form of tetrahedral shape. Its function is to dissipate the force from incoming waves by allowing water to flow around and between the tetrapods. Construction of tetrapods is very costly thus it is necesarry to conduct preliminary study such as numerical modelling to insure an effectiveness of design and upmost an impact towards environment. The main objective of this research is to determine the overtopping discharge over tetrapods with difference crests under waveenergy spectrum as generating the irregular wave. The volume of fluid technique (VOF) method with capabilities to solve Reynolds Average Navier-Stokes (RANS) equation in the numerical suite FLOW-3D is used in the study. This research also used to validate the non-dimensional overtopping discharge of the numerical model against the experiments of Tetrapod breakwater. Based on the observation, the surface elevation of the wave energy spectrum generated in the numerical simulationdecrease with distance from the wave generator. The numerical results highlight the importance of the height of the crest freeboard in reducing overtopping discharge (qreservoir = 0.0742 – 0.0249 m3/s). Moreover, the results have shown a good agreement between the validation and physical experiment with the percentage error within 10%.