Nearshore compound simulation by a Boussinesq-type wave model.

Georgios Klonaris, Constantine Memos, Christos Makris

Thursday 2 july 2015

9:40 - 10:00h at Antarctica (level 0)

Themes: IAHR/COPRI Symposium on Long Waves and Relevant Extremes

Parallel session: 10D. COPRI Symposium: Long waves and relevant extremes

A two-dimensional higher order Boussinesq-type model is developed able to simulate wave propagation in the coastal zone. The model reproduces very accurately the linear dispersion up to the traditional limit of deep water, kd _ 3, and it is derived to embed enhanced nonlinear characteristics compared to its weakly nonlinear counterparts (Karambas and Koutitas, 2002; Memos et al., 2005). In particular the description of the nonlinear amplitude dispersion is improved over the entire depth range. In order to form an integrated tool the model was extended to the surf and swash zones. Surf zone dynamics were simulated using the eddy viscosity concept (Kennedy et al., 2000). Extension to the swash zone was accomplished by applying a modified narrow slot technique to simulate wave runup. Bottom friction and subgrid turbulent mixing were also incorporated. Finally, the model is also capable of estimating the wave-induced current field. The numerical solution was accomplished by a finite difference generalized multi-step predictor-corrector scheme (Zlatev et al., 1984). Both 1DH and 2DH versions were validated against a variety of experimental tests including plane beaches and submerged bars. Both regular and irregular wave propagation and breaking were simulated. A comparison with a SPH model is depicted. Breaking and runup of a solitary wave were also modelled. A very demanding test including a rip channel was simulated to check the model's response too. The agreement, in general, is found fairly good and most of the nearshore phenomena are well described. References Karambas, Th.V., Koutitas, C., 2002. Surf and swash zone morphology evolution induced by nonlinear waves. J. Waterw. Port Coast. Ocean Eng. 128 (3). Kennedy, A.B., Chen, Q., Kirby, J.T., Dalrymple, R.A., 2000. Boussinesq modeling of wave transformation, breaking and runup. I: 1D. J. Waterw. Port Coast. Ocean Eng. 126 (1). Memos, C.D., Karambas, Th.V., Avgeris, I., 2005. Irregular wave transformation in the nearshore zone: experimental investigations and comparison with a higher order Boussinesq model. Ocean Eng. 32 (11-12). Zlatev, Z., Berkowicz, R., Prahm L.P., 1984. lmplementation of a variable stepsize variable formula method in the time-integration part of a code for treatment of long-range transport of air pollutants. J. Comput. Phys. 55 (2).