A novel imaging technique for identifying the locations of free-surface shapes was applied to three-dimensional hydraulic tests of coastal structures. Three-dimensional wave fields, consisting of superposed local reflected and diffracted waves, were measured around a breakwater and the mouth of a model harbor in a laboratory wave basin, and the results are consistent with the predictions of a Boussinesq-type equation model. The new technique was applied to surf zone waves to describe the organized deformation of breaking wave faces that evolve during wave propagation. Typical finger-shaped jets form in the wake of plunging jets, and a local depression trails behind a breaking wave front.

This paper presents that major computed flow filed above a boundary layer in a surf zone could be strongly affected by kinds of the boundary conditions (slip, non-slip and shift B.C. based on a log law) imposed at a bottom. The estimated bottom shear stress is also considerably dependent on the boundary conditions, which might cause over-or under-predictions for bed-loads transports in the sur-zone. In order to fill a gap between length-scales of predominant turbulent flows over and within the thin boundary layer, a two layer model (TLM) is applied to the boundary layer flows. TLM is found to give the reasonable boundary layer flows and also major flows over the boundary layer. This model may greatly contribute to practical largescale computations typically involving a significant gap of turbulence properties across the boundary layers.

The novel imaging technique for measuring planar free-surface shapes using a PC projector and digital camera is examined through model tests of planar wave field with coastal structures. The measured results reasonably represent local reflected and diffraction waves behind a breakwater and near a port mouth, which are consistent with computed ones.This technique is also applicable to the measurement of complex surface shapes of breaking waves.Typical finger-shaped jets formed after plunging overturning jets and local depression stretched behind a breaking-wave front are able to be obtained using the current technique.