Author(s): Z. L. Liao; S. W. Li; Y. Liu
Keywords: Infragravity waves; Shoal; Non-hydrostatic model
Abstract: Infragravity waves (IGWs) are waves with frequencies remarkably lower than short waves (SWs), typically between 0.004 and 0.04 Hz in prototype, and have important effects on many aspects of coastal hydrodynamics, such as beach and dune erosion, nearshore sediment transport, and short-wave groupiness on coral-reef flat. Utilizing the non-hydrostatic wave model SWASH, the previously reported phenomenon of IGWs being amplified in the presence of an underwater shoal was investigated in detail under non-breaking conditions. Nonlinear energy transfer from SWs to IGWs was found to consistently occur in the shoal region, and the effect was more significant on a milder bottom slope. Energetic free IGWs that are weakly correlated with the wave group were found to transmit behind the shoal, constituting a potential source of nearshore IGWs.