Experimental Investigation of Droplet Distributions from a Plunging
Breaker with Different Wind Conditions
Abstract
Understanding the droplet cloud and spray dynamics is important on the
study of the ocean surface and marine boundary layer.The role that the
wave energy and the type of wave breaking plays in the resulting
distribution and dynamics of droplets is yet to be understood. The aim
of this work was to generate violent plunging breakers in the laboratory
and analyze the spray production by the crest of the wave when it
impacts in the free surface. The droplet sizes and their dynamics were
measured and the effect of different wind speeds on the droplet
production was also considered. It was found that the mean radius
increases with the wave energy and the presence of larger droplets
(radius > 2 mm) in the vertical direction increases with
the presence of wind. Furthermore, the normalized distribution of
droplet sizes is consistent with the distribution of ligament-mediated
spray formation. Also, indications of turbulence affecting the droplet
dynamics at wind speeds of 5 m/s were found. The amount of large
droplets (radius >1 mm) found in this work was larger than
reported in the literature. An improved estimation of the initial
distribution of large droplets can largely affect the evolution of the
Sea Spray Generation Function, and therefore the estimation of energy
and mass transport in the marine boundary layer.