Junichi Otsuka, Yasunori Watanabe


Instantaneous velocity fields and suspended sediment concentration in surf zones were measured in a wave flume with a sloped sand bed by use of a particle image velocimetry (PIV) and an optical concentration sensor. This was done in order to elucidate sediment transport processes and clarify the relationship between kinetic turbulent energy and sediment suspension under a breaking wave turbulent flow field. In surf zones, sediments become highly suspended when strong turbulent energy reaches the bottom. High concentration was seen in the transition region where turbulent energy is at its maximum. Suspended sediment concentration in a plunging breaker is much higher than that in a spilling breaker because large-scale vortices are typically developed and stir-up much sediment. Suspended sediment is transported to a deeper region due to the undertow becoming highly developed after a wave crest has passed. In shallower regions, suspended sediment concentration increases linearly with an increasing of the turbulent energy. The slope of the approximation line for plunging breakers is steeper than that for spilling breakers.


breaking wave; suspended sediment; turbulent energy; particle image velocimetry (PIV)

Full Text:



Cox, D.T. and Kobayashi, N., 2000, Identification of intense, intermittent coherent motions under shoaling and breaking waves, Journal of Geophysical Research, 105, C6, 223-236.

Cox, D.T. and Anderson, S.L., 2001, Statistics of intermittent surf zone turbulence and observations of large eddies using PIV, Coastal Engineering Journal, 43, 121-131.

Huang, Z.C., Hwung, H.H., Hsiao, S.C. and Chang, K.A., 2009, Turbulence and energy dissipations of surf-zone spilling breakers, Coastal Engineering, 56, 733-746.

Kimmoun, O. and Branger, H., 2007, A particle images velocimetry investigation on laboratory surf- zone breaking waves over a sloping beach, Journal of Fluid Mechanics, 588, 353-397.

Nadaoka, K., Hino, M. and Koyano, Y., 1989, Structure of the turbulent flow field under breaking waves in the surf zone, Journal of Fluid Mechanics, 204, 359-387.

Ting, F.C.K. and Kirby, J.T., 1994, Observation of undertow and turbulence in a laboratory surf zone, Coastal Engineering, 24, 51-80.