Profiles of Void Fraction and Turbulent Dissipation under Breaking Waves in the Surf Zone

As waves shoal and break across the surf zone, much of their kinetic and potential energy is dissipated by turbulence and entrainment of bubbles into the water column. This surface injected turbulence advects down through the water column, modifying the eddy viscosity profile. Under strong breaking waves in shallow water, the surface breaking turbulence extends down to alter the structure of the bottom boundary layer, and in turn significantly effects sediment suspension and transport. As the effective eddy viscosity of the water column is determined by the effects of both bottom and surface generated turbulence, understanding these sources of turbulence and distribution through the water column has important implications in modeling momentum transfer in the nearshore. In this paper, measurements of void fraction profiles under breaking waves and concurrent turbulent shear estimates allow the depth of influence of bubbles and wave-breaking induced shear to be estimated in the nearshore.