Laboratory experiments for turbulence characteristics near the rubble mound breakwater

Laboratory data of velocity fields in front of a rubble-mound breakwater are presented and discussed for nonbreaking wave condition. Velocity measurements were conducted near the breakwater by an acoustic Doppler velocimeter (Nortek Vectrino) under regular waves. The raw data were analyzed by using a numerical-filtering scheme so that turbulent fluctuations are separated from the phase-dependent wave motions. Root mean square (RMS) values of the turbulent fluctuations in the vertical and wave directions were obtained. The spatial variations of the turbulent shear stress and of the turbulent kinetic energy (TKE) in front of the breakwater were determined. The results indicate that turbulent intensities take larger values when the wave contracts over the breakwater. On the other hand, maximum turbulent shear stress values were observed near the breakwater surface, as a consequence of the rough surface effect.