Large-Wave Simulation of Surface Tension Effect on Weak Spilling Breakers

The effect of surface tension on the evolution of weak spilling breakers is studied by performing large-wave simulations (LWS) of the free-surface flow developing by the interaction of a gravity free-surface wave and a surface shear-layer current. The flow models the evolution of gravity waves under the influence of wind shear. The surface tension modifies the dynamic free-surface condition and its effect depends on the dimensionless Weber number. The Euler equations are filtered according to the LWS formulation and solved numerically by a spectral method and a fractional-time-step scheme. The results indicate a stronger surface tension effect with decreasing Weber number values and increasing initial wave height. Specifically, decreasing the Weber number alters the size and shape of the characteristic bulge of spilling breakers and the toe position resulting in sharper slopes and angles of the free surface profile. The spiller wave height is reduced with decreasing Weber number.