Initiation of breaking process in Boussinesq-type wave models

The Breaking Celerity Index (BCI) is proposed as a new wave breaking criterion for phase resolving wave propagation models. The BCI effectiveness in determining the breaking initiation location has been verified for Boussinesq-type wave models against data from different experimental investigations conducted with incident regular waves propagating on uniform beach profiles (Utku 1999; Gonsalves Veloso dos Reis 1992). Moreover, in one case, the comparison has considered the numerical results from the COBRAS model based upon the Reynolds Averaged Navier Stokes (RANS) equations (Liu et al. 2000). Numerical simulations have been performed with the 1D-FUNWAVE model (Kirby et al. 1998). With regard to the adopted experimental conditions, the breaking location has been calculated for different trigger mechanisms (Zelt 1991; Kennedy et al. 2000; Utku 1999). The proposed BCI gives a better agreement with the physical data respect to the other trigger criteria, both for spilling and plunging breaking events. A second paper, in preparation, extends the confirmation of the BCI with further available data for uniform beach slopes (Ting and Kirby 1995; Lara et al. 2005) and for a barred beach (Tomasicchio and Sancho 2002) under regular and irregular incident wave conditions.