INTEGRATED STUDY ON THE VELOCITY FIELD INDUCED BY PLUNGING BREAKERS

Germán Daniel Rivillas, Adrián Pedrozo-Acuña, Rodolfo Silva, Alec Torres-Freyermuth, Cesar Gutierrez

Abstract


In this investigation we employ a technique called Bubble Image Velocimeter (BIV) to obtain measurements of flow fields in the surf-zone. This technique allows measurements of flow velocity in the aerated breaking zone, where other techniques are ineffective. The technique has been widely used to study flow propagation in front of vertical structures, it is employed in this study to estimate the velocity field induced by the propagation of a plunging wave travelling over an impermeable slope. The BIV measurements were compared to those obtained with an Acoustic Doppler Velocimeter (ADV) showing that the BIV technique is more suitable when the velocity field is estimated under the presence of an aerated flow. Moreover, the phase-averaged velocity fields obtained from the numerical model were compared against those evaluated from the BIV measurements. A reliable estimation of the VOF-type numerical derivations in the surf zone was established. In the swash zone, an over prediction of the offshore flow was identified.

Keywords


BIV; RANS; velocity fields; breaking waves; surf zone; swash zone

References


Elgar, S., Herbers, T. H. C., and Guza, R. T. (1994) Reflection of ocean surface gravity waves from a natural beach. J. Phys. Oceanogr., 24, 1503-1511

Govender, K., Mocke, G.P., and Alport M.J., 2004. Dissipation of isotropic turbulence and length-scale measurements through the wave roller in laboratory spilling waves. J Geophys Res. 109 (C08018):5115-5124

Hassan, Y.A., Schmidl, W.D., and Ortiz-Villafuerte, J. (1998) Investigation of three-dimensional two phase flow structures in a bubbly pipe. Meas. Sci Technol., 9, 309-326

Holland, K.T, Puleo, J.A., and Kooney, T.N. (2001) Quantification of swash flows using video-based particle image velocimetry. Coastal Engineering, 42(2), 65-77http://dx.doi.org/10.1016/S0378-3839(01)00022-9

Jayaratne, R., Hunt-Raby, A., Bullock, G., and Bredmose, H. (2008) Individual violent overtopping events: new insights. In: Proceedings of the 31 th international conference on coastal engineering, Hamburg, World Scientific., 1-13

Lindken, R., and Merzkirch, W. (2002) A novel PIV technique for measurements in multi-phase bubby flows. Exp. Fluids, 33, 814-825

Lin, P., and Liu, P.F. (1998a) A numerical study of breaking waves. J.Fluid Mech., 359, 239-264http://dx.doi.org/10.1017/S002211209700846X

Lin, P., and Liu, P.F. (1998b) Turbulent transport, vorticity dynamics and solute mixing under plunging waves in surf zones. J.Geopsh Res.,103(15), 15667-15964

Nishino, K., Kato, H., and Torii, K. (2000) Stereo imaging for simultaneous measurement of size and velocity of particles in dispersed two-phase flow. Meas. Sci Technol., 11, 633-645http://dx.doi.org/10.1088/0957-0233/11/6/306

Petti, M., Longo, S. (2001) Turbulence experiments in the swash zone. Coastal Engineering, 43, 1-24http://dx.doi.org/10.1016/S0378-3839(00)00068-5

Pedrozo-Acuña, A., Simmonds, D. J., and Reeve, D. E. (2008) Wave-impact characteristics of plunging breakers acting on gravel beaches. Mar. Geol. K, 253(1): 26-35http://dx.doi.org/10.1016/j.margeo.2008.04.013

Ray, S.D. (2002) Applied photographic optics. Focal, Oxford, 215-233

PMid:12024804

Raubenheimber, B., Elgar, S., and Guza, R. T. (1996) Wave transformation across the inner surf zone. J. Geophys. Res., 101, 25.589-25.597.

Rivillas-Ospina, G. D., Pedrozo-Acuña, A., and Silva, R., and Gutierrez, C (2011) Estimation of the velocity field induced by plunging breakers in the surf zone. Exp. Fluids, 52, 53-68.http://dx.doi.org/10.1007/s00348-011-1208-x

Ryu, Y., Chang, K.A., and Lim, H.J. (2005) Use of bubble image velocimetry for measurement of plunging wave impinging on structure and associated greenwater. Meas. Sci Technol., 16, 1945-1953http://dx.doi.org/10.1088/0957-0233/16/10/009

Ryu, Y., Chang K.A., and Mercier, R. (2007) Runup and green water velocities due to breaking waves impinging and overtopping. Exp. Fluids., 43, 555-567http://dx.doi.org/10.1007/s00348-007-0332-0

Ryu, Y., and Chang K.A. (2008) Green water void fraction due to breaking wave impinging and overtopping. Exp. Fluids., 45, 883-898http://dx.doi.org/10.1007/s00348-008-0507-3

Scott, C.P., Cox, D.T., Maddux, T.B., and Long, J. W. (2005) Large-scale laboratory observations of turbulence on a fixed barred beach. Meas. Sci. and Tech., 16, 1903-1912.http://dx.doi.org/10.1088/0957-0233/16/10/004

Ting, F.C.K., and Kirby J.T. (1994) Observation of undertow and turbulence in a laboratory surf zone. Coastal Engineering, 24(1-2), 51-80http://dx.doi.org/10.1016/0378-3839(94)90026-4

Ting, F.C.K., and Kirby, J.T. (1995) Dynamics of surf-zone turbulence in a strong plunging breaker.

Ting, F.C.K., and Kirby, J.T. (1996) Dynamics of surf-zone turbulence in a strong plunging breaker. Coastal Engineering, 27, 131-160http://dx.doi.org/10.1016/0378-3839(95)00037-2

Ting, F.C.K. (2006) Large-scale turbulence under a solitary wave. Coastal Engineering, 53(5-6), 441-462http://dx.doi.org/10.1016/j.coastaleng.2005.11.004


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