A time-domain Boussinesq model was applied to modeling wave interference
and its effects on nearshore circulation in San Francisco Bar and the
adjacent Ocean Beach, CA. The model predicted the wave interference
phenomena caused by the ebb shoal, with interference scales consistent
with the Radar observation. Model results reveal that small-scale
fingering structures in the wave height distribution result from wave
interference and are persistent with nodal lines unchanged with time.
Nearshore circulation predicted by the model shows small-scale flow
structures tied with the wave modulation patterns. However, the
small-scale modulation in the wave field seems not to generate
alongshore variation in wave setup at similar scales. Therefore, in a
large-scale view, the alongshore currents predicted by the Boussinesq
model still keep the general features shown in a wave-averaged model,
such as the flow divergence caused by the pressure gradient force
associated with the alongshore variation of wave setup. The time-domain
Boussinesq model predicted the spatial variability of wave-induced
processes. The alongshore-varying wave breakers caused by wave
interference are the source of the vorticity generation, inducing
energetic vortex eddies nearshore.