Effect Of Coastline Reflection On The Performance Of A Submerged Breakwater

Submerged breakwater can reflect and dissipate the incident wave energy and thenprotect the coastline and coastal structures. In engineering design, the transmissioncoefficient and the reflection coefficient of the submerged breakwater must bedetermined. An effective submerged breakwater must have small transmissioncoefficient. On the other hand, the low reflection coefficient of breakwater issignificant for suppressing the seabed scouring in front of the structure and the safenavigation of the crafts. So we need study the transmission and reflection coefficientsof the submerged breakwater.Many analytical, experimental and numerical studies on the reflection andtransmission coefficients of submerged breakwaters have been carried out. Theprevious studies mainly discuss the effects of the breakwater size, the submerged depthand the incident wave parameter on the hydrodynamic performance of the breakwater.Some significant results have been presented. However, we found that the coastlinereflection also has some effects on the hydrodynamic performance of the submergedbreakwater. But relevant studies on this topic have been scarcely referred. This paperexamines the effect of coastal reflection coefficient on the reflection and transmissioncoefficients of submerged breakwaters.Based on the linear potential theory, the Laplace equation is adopted as the fieldequation. The method of separation of variables is used to solve the field equation. Thevelocity potential is determined by matching the relevant boundary conditions. In thispaper, the effects of the space between the submerged breakwater and the coastline, thesubmerged depth of the structure, the width of the submerged breakwater, and thecoastline reflection coefficients on the reflection and transmission coefficients of thesubmerged breakwater are discussed. Numerical results indicated that coastlinereflection increases both reflection and transmission coefficients of the submergedbreakwater. The submerged depth has the most significant effect on the performance ofthe breakwater. The effects of the space between the coastline and breakwater and the breakwater width on the performance of the breakwater is more significant for lowfrequency waves. The present study should be helpful for practical engineering.