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Structure of the turbulent flow field under breaking waves in the surf zone

Published online by Cambridge University Press:  26 April 2006

Kazuo Nadaoka ,
Mikio Hino  and
Yoshiji Koyano
Kazuo Nadaoka
Affiliation:
Tokyo Institute of Technology, 2–12–1, O-okayama, Meguro-ku, Tokyo 152, Japan
Mikio Hino
Affiliation:
Tokyo Institute of Technology, 2–12–1, O-okayama, Meguro-ku, Tokyo 152, Japan
Yoshiji Koyano
Affiliation:
Tokyo Institute of Technology, 2–12–1, O-okayama, Meguro-ku, Tokyo 152, Japan
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Abstract

The structure of turbulence and its role in the breaking wave dynamics within the surf zone have been investigated through laboratory experiments using several flow visualization techniques and a fibre-optic LDV system. The results indicate that there exists a characteristic structure of large-scale eddies referred to here as ‘horizontal eddies’ and ‘obliquely descending eddies’, which has a significant role in the generation of Reynolds stress and thus affects the deformation of the mean flow field. The experiments also reveal that these eddies caused by the wave breaking bring a large amount of vorticity (with non-zero average) into otherwise almost irrotational velocity fields, resulting in the generation of vorticity-related mean flow fields as well as turbulence (vorticity-containing velocity fluctuation). This means that the breaking waves in the surf zone can be regarded as pseudowaves which consist of irrotational velocity components as ‘wave motion’ and appreciable amounts of rotational mean velocity components as ‘eddying motion’ (with non-zero mean vorticity) together with turbulence. It is found that the generation of the mean rotational velocity component due to wave breaking causes considerable increase in mass and momentum transport, as compared with ordinary non-breaking waves, and thus a decrease in wave height.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 204 , July 1989 , pp. 359 - 387
Copyright
© 1989 Cambridge University Press

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References

Battjes, J. A. & Sakai, T., 1980 Velocity field in a steady breaker. J. Fluid Mech. 111, 421–437.Google Scholar
Dean, R. G.: 1965 Stream function representation of nonlinear ocean waves. J. Geophys. Res. 70, 4561–4572.Google Scholar
Hattori, M. & Aono, T., 1985 Experimental study on turbulence structures under breaking waves. Coastal Engng Japan 28, 97–116.Google Scholar
Hino, M. & Kashiwayanagi, M., 1979 Applicability of Dean's stream function method to estimation of orbital wave velocity and wave set-down and set-up. Coastal Engng Japan 22, 11–20.Google Scholar
Hino, M., Sawamoto, M., Yamashita, T., Hironaga, M. & Muramoto, T., 1984 Prototype 2-dimensional LDV Adopting Optical Fibres, Laser-Doppler Velocimetry and Hot-Wire/Film Anemometry, pp. 97–105. Association for the Study of Flow Measurement, Osaka, Japan.
Lambrakos, K. F.: 1981 Extended velocity potential wave kinematics. J. Waterways Port Coastal Ocean Div. ASCE 107, (WW3) 159–174.Google Scholar
Miller, R. L.: 1976 Role of vortices in the surf zone prediction: sedimentation and wave forces. Beach and Nearshore Sedimentation, SEPM Spec. Pub. 23, pp. 92–114.Google Scholar
Nadaoka, K.: 1986 A fundamental study on shoaling and velocity field structure of water waves in the nearshore zone. Doctoral Dissertation, Tokyo Inst. of Tech. (reproduced in Tech. Rep. of Dept. Civil Engng, Tokyo Inst. Tech., No. 36, pp. 33–125, 1986.Google Scholar
Nadaoka, K. & Hino, M., 1984 Conformal mapping solution of a wave field on the arbitrarily shaped sea bed. Proc. 19th Conf. on Coastal Engng, pp. 1192–1208. ASCE.
Nadaoka, K. & Kondoh, T., 1982 Laboratory measurements of velocity field structure in the surf zone by LDV. Coastal Engng Japan 25, 125–145.Google Scholar
Nadaoka, K., Kondoh, T. & Tanaka, N., 1982 The structure of velocity field within the surf zone revealed by means of laser-Doppler anemometry. Rep. Port and Harbour Res. Inst., Vol. 21, No. 2, pp. 49–106 (in Japanese).Google Scholar
Peregrine, D. H.: 1983 Breaking waves on beaches, Ann. Rev. Fluid Mech. 15, 149–178.Google Scholar
Peregrine, D. H. & Svendsen, I. A., 1978 Spilling breakers, bores and hydraulic jumps. Proc. 16th Conf. on Coastal Engng, pp. 540–550. ASCE.
Reid, R. O.: 1957 Correlation of water level variation of non-linear ocean waves. Proc. 6th Coastal Engng, pp. 749–786. ASCE.
Sakai, T., Inada, Y. & Sandanbata, I., 1982 Turbulence generated by wave breaking on beach. Proc. 18th Conf. on Coastal Engng, pp. 3–21. ASCE.
Sakai, T. & Iwagaki, Y., 1978 Estimation of water particle velocity of breaking waves. Proc. 16th Conf. on Coastal Engng, pp. 551–568. ASCE.
Sakai, T., Sandanbata, I. & Uchida, M., 1984 Reynolds stress in surf zone. Proc. 19th Conf. on Coastal Engng, pp. 42–53. ASCE.
Stive, M. J. F.: 1980 Velocity and pressure field of spilling breakers. Proc. 17th Conf. on Coastal Engng, pp. 547–566. ASCE.
Stive, M. J. F. & Wind, H. G. 1982 A study of radiation stress and set-up in the nearshore region. Coastal Engng 6, 1–26.Google Scholar
Svendsen, I. A.: 1984a Wave hights and set-up in a surf zone. Coastal Engng 8, 303–329.Google Scholar
Svendsen, I. A.: 1984b Mass flux and undertow in a surf zone. Coastal Engng 8, 347–365.Google Scholar
Tennekes, H. & Lumley, J. L., 1972 A First Course in Turbulence. MIT Press.