Akio Okayasu, Keiichiro Fujii, Masahiko Isobe


Influence of turbulence on sediment pickup rate was investigated. Pickup rates with external turbulence generated by a grid structure were measured in a channel. It was found that the rates were much larger than those for non-turbulent conditions. A new formula in which external turbulence was taken into account for Shields parameter evaluation was proposed. In the formula, effect of inertia force by turbulence acting on sediment particles was included as well as the enlarged drag force caused by fluctuating velocity.


pickup function; external turbulence; Shields parameter; wave breaking; sediment transport

Full Text:



Cheng, N.S., B.M. Sumer, and J. Freds√łe. 2003. Investigation of bed shear stresses subject to external turbulence, International Journal of Heat and Fluid Flow, 24, 816-824. http://dx.doi.org/10.1016/S0142-727X(03)00088-2

Jones, W.P., and B.E. Launder. 1972. The prediction of laminarization with a two-equation model of turbulence, International Journal of Heat Mass Transfer, 15, 301-314. http://dx.doi.org/10.1016/0017-9310(72)90076-2

Nadaoka, K., S. Ueno, and T. Igarashi, 1988. Sediment suspension due to large scale eddies in the surf zone, Proceedings of 21 st International Conference on Coastal Engineering, ASCE, 1646-1660.

Nielsen, P. 1992. Coastal bottom boundary layer and sediment transport, World Scientific, Singapore, 224-226. PMid:1378214

van Rijn, L.C. 1984. Sediment pick-up functions. Journal of Hydraulic Engineering, 110(10), 1494-1502.http://dx.doi.org/10.1061/(ASCE)0733-9429(1984)110:10(1494)

Sumi, H., T. Takae, and T. Nozaki. 2009. Experimental study on temporal and spatial distributions of bottom shear stresses in surf zone, Journal of JSCE, B2, 65(1), 101-105. (Japanese)

Suzuki, T., A. Okayasu, and T. Shibayama. 2007. A numerical study of intermittent sediment concentration under breaking waves in the surf zone, Coastal Engineering, 54, 433-444. http://dx.doi.org/10.1016/j.coastaleng.2006.11.002

DOI: https://doi.org/10.9753/icce.v32.sediment.14