Keywords
Q3D nearshore current model
surface roller
wave breaking
How to Cite
Abstract
This paper develops a quasi-three-dimensional nearshore current model which accounts for excess shoreward volume fluxes due to waves and surface rollers. The model splits the water column at the wave trough level and solves two different layers of 2DH momentum equations. The first layer covers above the trough level and determines the shear stress at the trough level while the the second layer covers over the entire depth and determines the volume flux due to mean current components. Linearly approximated vertical profile of the shear stress and corresponding turbulent eddy viscosity model enables the present model to yield analytical explicit expression of the horizontal velocity profiles, which enhance computational efficiency of the model. The extended model was applied to predictions of longshore current velocity on the long straight beach and circulation current patterns behind the detached submerged breakwater on the plane beach. Excellent agreement between model predictions and measurements supports the validity of the model and importance of quasi-three-dimensional features around the submerged break water.References
Cox, D.T. and N. Kobayashi. 1996. Undertow profiles in the bottom boundary layer under breaking waves, Proc. 25th Int. Conf. on Coast. Eng., ASCE, 3194-3206.
Hamilton, D. G. and Ebersole, B. A. 2001. Establishing uniform longshore currents in a large-scale laboratory facility, Coastal Eng., 42, 199-218.http://dx.doi.org/10.1016/S0378-3839(00)00059-4
Kuroiwa, M., H. Noda and Y. Houchi. 1997. A quasi-three dimensional model of wave-induced current in the surf zone, Proc. of Coast. Eng., JSCE, vol.44, 151-155 (in Japanese).
Madsen, O. S. 1994. Spectral wave-current bottom boundary layer flows, Proc. 24th Int. Conf. on Coast. Eng., ASCE, 384-398.
Ohnaka, S., A. Watanabe and M. Isobe. 1989. Numerical computation of wave field by the unsteady mild slope equation extended to wave-current coexisting field, Proc. of Coast. Eng., JSCE, 91-95 (in Japanese).
Putrevu, U., and Svendsen, I. A. 1992. A mixing mechanism in the nearshore region, Proc. 23rd Int. Conf. on Coast. Eng., ASCE, 2758-2771
Sanchez-Arcilla, A., Collado, F., and A. Rodriguez. 1992. Vertically varying velocity field in Q-3D nearshore circulation, Proc. 23rd Int. Conf. on Coastal Eng. 2811-2824.
Svendsen, I.A. and U. Putrevu. 1994. Nearshore mixing and dispersion, Proc. Math. and Phys. Sciences, vol.445, 561-576.http://dx.doi.org/10.1098/rspa.1994.0078
Tajima, Y., and O. S. Madsen. 2006. Modeling near-shore waves, surface rollers, and undertow velocity profiles, J. of Waterway, Port, Coastal and Ocean Eng., Vol. 132, No. 6, 429-438.http://dx.doi.org/10.1061/(ASCE)0733-950X(2006)132:6(429)
Tajima, Y. and S. Sato. 2010. Local concentration of slowly varying wave and current fields around the abruptly changing bottom slopes along the shore, Proc. 32nd Int. Conf. Coast. Eng.,
Tajima, Y., S. Sato, T. Shimozono and M. Isobe. 2007. Modeling of wave-induced current around submerged detached breakwaters, Proc. of Int. Conf. on Coast. Str. 2007, CD-ROM published by World Scientific Publishing Corp. and East Meets West Productions.