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Infragravity Wave Modeling with CGWAVE


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I am trying to model the wave agitation within a harbour basin caused by infra-gravity (IG) waves.

These long period (20 - 200sec) waves are formed under the windsea wave groups and are bound to them,

hence, their propagation characteristics (celerity and direction)are those of the wave group. Moreover, their "shoaling" characteristics differ from the free gravity waves.

The IG waves are released and can propagate as free gravity waves when the wave group formation ceases to exist,

either due to depth induced breaking along the breaker zone or due to diffraction at the harbour entrance.

Hence, in order to model the wave penetration into a harbour with CGWAVE, the input wave characteristics at the offshore boundary should be such that the resulting characteristics (amplitude and direction)at the harbour

entrance are approximately those of the IG characteristics when they are released from the group at that area.

Due to the very long period that the IG waves exhibit, the CGWAVE model region must extend far away form the the harbour entrance. If we provide the free IG wave characteristics at the offshore boundary, the nearshore characteristics (amplitude and direction) would differ from the actual nearshore charcateristics at the zone of their release.

My question is how to setup the model region for IG waves. In addition, it seems to me that the "Infragravity Wave Toolbox" that may be used to create the IG wave spectrum at a specific water depth for a specified windsea spectrum, outputs the components' spectral density rather than amplitude and therefore the IG wave height at the boundary is unrealistic.

Thank you.


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