Numerical Analysis of Synchronous Edge Wave Known as the Driving Mechanism of Beach Cusp

摘要

In this study,we carried out the 3D numerical simulation to investigate the hydraulic characteristics of Synchronous Edge wave known as the driving mechanism of beach cusp using the Tool Box called the ihFoam that has its roots on the OpenFoam.As a wave driver,RANS (Reynolds Averaged Navier-Stokes equation) and mass conservation equation are used.In doing so,we materialized short-crested waves known as the prerequisite for the formation of Synchronous Edge waves by generating two obliquely colliding Cnoidal waves.Numerical results show that as can be expected,flow velocity along the cross section where waves are focused are simulated to be much faster than the one along the cross section where waves are diverged.It is also shown that along the cross section where waves are focused,up-rush is moving much faster than its associated back-wash,but a duration period of up-rush is shortened,which complies the typical characteristics of nonlinear waves.On the other hand,due to the water-merging effect triggered by the redirected flow toward wave-diverging area at the pinacle of run-up,along the cross section where waves are diverged,offshore-ward velocity is larger than shore-ward velocity at the vicinity of shore-line,while at the very middle of shoaling process,the asymmetry of flow velocity leaned toward the shore is noticeably weakened.Considering that these flow characteristics can be found without exception in Synchronous Edge waves,the numerical simulation can be regarded to be successfully implemented.In doing so,new insight about how the boundary layer streaming occur are also developed.