Experimental and numerical study on breaking solitary wave over sloping-step geometry

The breaking of a water solitary wave over a sloping-step geometry is studied both experimentally and numerically. There are three parameters for this breaking phenomenon, but we find that the breaker type can be sorted primarily by a single parameter, i. e., the ratio of the solitary-wave height to water depth above the step. As this parameter increases, breaker type changes from spilling to plunging and finally to collapsing if the sloping angle of the step is not small (30° or greater). If the sloping angle is small (about 10°), breaker type changes from spilling to plunging but no collapsing occurs. Flow velocities in the water measured by PIV show that the mechanism of collapsing breaker is quite different from that of spilling and plunging breakers.