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Flow kinematics and air entrainment under laboratory spilling breaking waves

Published online by Cambridge University Press:  08 November 2019

Byoungjoon Na
Affiliation:
Department of Ocean Engineering, Texas A&M University, College Station, TX 77843, USA
Kuang-An Chang*
Affiliation:
Department of Ocean Engineering, Texas A&M University, College Station, TX 77843, USA Zachry Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX 77843, USA
Ho-Joon Lim
Affiliation:
Offshore Technology Services, TechnipFMC, Houston, TX 77079, USA
*
Email address for correspondence: kchang@tamu.edu

Abstract

Laboratory measurements of velocity fields and void fraction under spilling breaking waves are presented. Modified particle image velocimetry was used to quantify the flow kinematics and turbulence while fibre optic reflectometry was used to quantify the breaking-induced air entrainment inside the aerated region of the spilling breakers. The measurements confirmed that the ratio of the local energy flux and the local energy density sharply increases and exceeds the threshold value of 0.85 near the onset of breaking. Based on the measured velocity fields, the maximum horizontal velocity reached $1.1C$ at the onset of breaking, with $C$ being the phase speed of the primary breaking wave. The maximum horizontal velocity then reached $1.5C$ at approximately one-quarter of a wave period after the onset of breaking. The results also confirmed that the wavelet-educed turbulence length scale estimates are comparable to the previously reported values with different wave parameters, suggesting that the dependence of the size of energy-containing eddies on the physical scales of the breaking waves is insignificant. The measured void fraction showed a similarity profile although the measurement locations span one wavelength. The mean kinetic energy, turbulent kinetic energy, potential energy and total energy were quantified with and without the void fraction being accounted for. Results show near 60 % and 40 % overestimates of the kinetic energy and the potential energy if the void fraction is not considered. After correcting the density variation due to air entrainment, the total energy dissipated following an exponential decay, with 43 % and 65 % energy being dissipated at one and two wavelengths downstream from the breaking point, respectively. The equipartition assumption was found to be applicable before and during the entire breaking process in the present spilling breakers.

Type
JFM Papers
Copyright
© 2019 Cambridge University Press 

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References

Adrian, R. J., Christensen, K. T. & Liu, Z.-C. 2000 Analysis and interpretation of instantaneous turbulent velocity fields. Exp. Fluids 29 (3), 275290.Google Scholar
Anguelova, M. D. & Huq, P. 2012 Characteristics of bubble clouds at various wind speeds. J. Geophys. Res. 117, C03036.Google Scholar
Anguelova, M. D. & Huq, P. 2018 Effects of salinity on bubble cloud characteristics. J. Mar. Sci. Engng 6 (1), 1.Google Scholar
Banner, M., Barthelemy, X., Fedele, F., Allis, M., Benetazzo, A., Dias, F. & Peirson, W. 2014 Linking reduced breaking crest speeds to unsteady nonlinear water wave group behavior. Phys. Rev. Lett. 112, 114502.Google Scholar
Banner, M. & Fooks, E. 1985 On the microwave reflectivity of small-scale breaking water waves. Proc. R. Soc. Lond. A 399 (1816), 93109.Google Scholar
Barthelemy, X., Banner, M. L., Peirson, W. L., Fedele, F., Allis, M. & Dias, F. 2018 On a unified breaking onset threshold for gravity waves in deep and intermediate depth water. J. Fluid Mech. 841, 463488.Google Scholar
Blanchard, D. C. & Syzdek, L. 1970 Mechanism for the water-to-air transfer and concentration of bacteria. Science 170 (3958), 626628.Google Scholar
Blanchard, D. C. & Woodcock, A. H. 1957 Bubble formation and modification in the sea and its meteorological significance. Tellus 9, 145158.Google Scholar
Blenkinsopp, C. E. & Chaplin, J. R. 2007 Void fraction measurements in breaking waves. Proc. R. Soc. Lond. A 463 (2088), 3151.Google Scholar
Blenkinsopp, C. E. & Chaplin, J. R. 2011 Void fraction measurements and scale effects in breaking waves in freshwater and seawater. Coast. Engng 58, 417428.Google Scholar
Brocchini, M. & Peregrine, D. H. 2001 The dynamics of strong turbulence at free surfaces. Part 1. Description. J. Fluid Mech. 449, 225254.Google Scholar
Camussi, R. 2002 Coherent structure identification from wavelet analysis of particle image velocimetry data. Exp. Fluids 32 (1), 7686.Google Scholar
Camussi, R. & Felice, F. D. 2006 Statistical properties of vortical structures with spanwise vorticity in zero pressure gradient turbulent boundary layers. Phys. Fluids 18 (3), 035108.Google Scholar
Carey, W. M., Fitzgerald, J. W., Monahan, E. C. & Wang, Q. 1993 Measurement of the sound produced by a tipping trough with fresh and salt water. J. Acoust. Soc. Am. 93, 31783192.Google Scholar
Chang, K.-A., Ariyarathne, K. & Mercier, R. 2011 Three-dimensional green water velocity on a model structure. Exp. Fluids 51 (2), 327345.Google Scholar
Chang, K.-A., Lim, H. J. & Su, C. B. 2002 A fibre optic Fresnel ratio meter for measurements of solute concentration and refractive index change in fluids. Meas. Sci. Technol. 13 (12), 19621965.Google Scholar
Chang, K.-A., Lim, H.-J. & Su, C. B. 2003 Fiber optic reflectometer for velocity and fraction ratio measurements in multiphase flows. Rev. Sci. Instrum. 74, 35593565.Google Scholar
Chang, K.-A. & Liu, P. L.-F. 1998 Velocity, acceleration and vorticity under a breaking wave. Phys. Fluids 10 (1), 327329.Google Scholar
Chang, K.-A. & Liu, P. L.-F. 1999 Experimental investigation of turbulence generated by breaking waves in water of intermediate depth. Phys. Fluids 11 (11), 33903400.Google Scholar
Christensen, E. D. 2006 Large eddy simulation of spilling and plunging breakers. Coast. Engng 53 (5), 463485.Google Scholar
Cowen, E. A., Sou, I. M., Liu, P. L.-F. & Raubenheimer, B. 2003 Particle image velocimetry measurements within a laboratory-generated swash zone. J. Engng Mech. 129 (10), 11191129.Google Scholar
Cox, D. T. & Shin, S. 2003 Laboratory measurements of void fraction and turbulence in the bore region of surf zone waves. J. Engng Mech. 129 (10), 11971205.Google Scholar
Deane, G. B. & Stokes, M. D. 2002 Scale dependence of bubble creation mechanisms in breaking waves. Nature 418 (6900), 839844.Google Scholar
Derakhti, M., Banner, M. & Kirby, J. 2018 Predicting the breaking strength of gravity water waves in deep and intermediate depth. J. Fluid Mech. 848, R2.Google Scholar
Derakhti, M. & Kirby, J. 2014 Bubble entrainment and liquid–bubble interaction under unsteady breaking waves. J. Fluid Mech. 761, 464506.Google Scholar
Derakhti, M. & Kirby, J. 2016 Breaking-onset, energy and momentum flux in unsteady focused wave packets. J. Fluid Mech. 790, 553581.Google Scholar
Diorio, J. D., Liu, X. & Duncan, J. H. 2009 An experimental investigation of incipient spilling breakers. J. Fluid Mech. 633, 271283.Google Scholar
Drazen, D. A. & Melville, W. K. 2009 Turbulence and mixing in unsteady breaking surface waves. J. Fluid Mech. 628, 85119.Google Scholar
Drazen, D. A., Melville, W. K. & Lenain, L. 2008 Inertial scaling of dissipation in unsteady breaking waves. J. Fluid Mech. 611, 307332.Google Scholar
Duncan, J. 2001 Spilling breakers. Annu. Rev. Fluid Mech. 33 (1), 519547.Google Scholar
Duncan, J. H., Philomin, V., Qiao, H. & Kimmel, J. 1994 The formation of a spilling breaker. Phys. Fluids 6 (9), S2.Google Scholar
Duncan, J. H., Qiao, H., Philomin, V. & Wenz, A. 1999 Gentle spilling breakers: crest profile evolution. J. Fluid Mech. 379, 191222.Google Scholar
Farge, M. 1992 Wavelet transforms and their applications to turbulence. Annu. Rev. Fluid Mech. 24 (1), 395458.Google Scholar
Farmer, D. M., McNeil, C. L. & Johnson, B. D. 1993 Evidence for the importance of bubbles in increasing air sea gas flux. Nature 361 (6413), 620623.Google Scholar
Govender, K., Mocke, G. P. & Alport, M. J. 2002 Video-imaged surf zone wave and roller structures and flow fields. J. Geophys. Res. 107 (C7), 9-1-9-21.Google Scholar
Govender, K., Mocke, G. P. & Alport, M. J. 2004 Dissipation of isotropic turbulence and length-scale measurements through the wave roller in laboratory spilling waves. J. Geophys. Res. 109 (C8).Google Scholar
Graham, A., Woolf, D. K. & Hall, A. J. 2004 Aeration due to breaking waves. Part I: bubble populations. J. Phys. Oceanogr. 34 (5), 9891007.Google Scholar
Hoque, A. & Aoki, S.-i. 2005 Distributions of void fraction under breaking waves in the surf zone. Ocean Engng 32 (14), 18291840.Google Scholar
Huang, Z.-C., Hwung, H.-H. & Chang, K.-A. 2010 Wavelet-based vortical structure detection and length scale estimate for laboratory spilling waves. Coast. Engng 57 (9), 795811.Google Scholar
Hwung, H. H., Chyan, J. M. & Chung, Y. C. 1992 Energy dissipation and air bubbles mixing inside surf zone. In 23rd Intl Conf. on Coastal Engineering (ASCE), Venice, Italy, vol. 1, pp. 308321.Google Scholar
Kalvoda, P. M., Xu, L. & Wu, J. 2003 Macrobubble clouds produced by breaking wind waves: A laboratory study. J. Geophys. Res. 108 (C6).Google Scholar
Kiger, K. T. & Duncan, J. H. 2012 Air-entrainment mechanisms in plunging jets and breaking waves. Annu. Rev. Fluid Mech. 44, 563596.Google Scholar
Kimmoun, O. & Branger, H. 2007 A particle image velocimetry investigation on laboratory surf-zone breaking waves over a sloping beach. J. Fluid Mech. 588, 353397.Google Scholar
Koga, M. 1982 Bubble entrainment in breaking wind waves. Tellus 34 (5), 481489.Google Scholar
Lamarre, E. & Melville, W. K. 1991 Air entrainment and dissipation in breaking waves. Nature 351, 469.Google Scholar
Lamarre, E. & Melville, W. K. 1992 Instrumentation for the measurement of void-fraction in breaking waves: laboratory and field results. IEEE J. Ocean. Engng 17 (2), 204215.Google Scholar
Leifer, I. & de Leeuw, G. 2006 Bubbles generated from wind-steepened breaking waves: 1. Bubble plume bubbles. J. Geophys. Res. 111 (C6).Google Scholar
Lim, H. J., Chang, K. A., Huang, Z. C. & Na, B. 2015 Experimental study on plunging breaking waves in deep water. J. Geophys. Res. 120, 20072049.Google Scholar
Lim, H.-J., Chang, K.-A., Su, C. B. & Chen, C.-Y. 2008 Bubble velocity, diameter, and void fraction measurements in a multiphase flow using fiber optic reflectometer. Rev. Sci. Instrum. 79 (12), 125105.Google Scholar
Lin, C., Hsieh, S. C., Lin, I. J., Chang, K. A. & Raikar, R. V. 2012 Flow property and self-similarity in steady hydraulic jumps. Exp. Fluids 53, 15911616.Google Scholar
Loewen, M. R., O’Dor, M. A. & Skafel, M. G. 1996 Bubbles entrained by mechanically generated breaking waves. J. Geophys. Res. 101 (C9), 2075920769.Google Scholar
Longo, S. 2009 Vorticity and intermittency within the pre-breaking region of spilling breakers. Coast. Engng 56 (3), 285296.Google Scholar
Longuet-Higgins, M. S. 1996 Capillary jumps on deep water. J. Phys. Oceanogr. 26 (9), 19571965.Google Scholar
Longuet-Higgins, M. S. & Turner, J. S. 1974 An ‘entraining plume’ model of a spilling breaker. J. Fluid Mech. 63 (1), 120.Google Scholar
Mason, M. A. 1952 Some observations of breaking waves. In Gravity Waves, vol. Circ. 521, pp. 215220. National Bureau Standards.Google Scholar
Melville, W. K., Veron, F. & White, C. J. 2002 The velocity field under breaking waves: coherent structures and turbulence. J. Fluid Mech. 454, 203233.Google Scholar
Monahan, E. C., Wang, Q., Wang, X. & Wilson, M. B. 1994 Air entrainment by breaking waves: a laboratory assessment. AER Technol. 187, 2126.Google Scholar
Monahan, E. M. & Zietlow, C. R. 1969 Laboratory comparisons of fresh-water and salt-water whitecaps. J. Geophys. Res. 74, 69616966.Google Scholar
Mori, N., Suzuki, T. & Kakuno, S. 2007 Experimental study of air bubbles and turbulence characteristics in the surf zone. J. Geophys. Res. 112 (C5).Google Scholar
Na, B., Chang, K.-A., Huang, Z.-C. & Lim, H.-J. 2016 Turbulent flow field and air entrainment in laboratory plunging breaking waves. J. Geophys. Res. 121 (5), 29803009.Google Scholar
Nadaoka, K., Kino, M. & Koyano, Y. 1989 Structure of turbulent flow field under breaking waves in the surf zone. J. Fluid Mech. 204, 359387.Google Scholar
Perlin, M., Choi, W. & Tian, Z. 2013 Breaking waves in deep and intermediate waters. Annu. Rev. Fluid Mech. 45, 115145.Google Scholar
Perlin, M., He, J. & Bernal, L. P. 1996 An experimental study of deep water plunging breakers. Phys. Fluids 8 (9), 23652374.Google Scholar
Qiao, H. & Duncan, J. H. 2001 Gentle spilling breakers: crest flow-field evolution. J. Fluid Mech. 439, 5785.Google Scholar
Rapp, R. J. & Melville, W. K. 1990 Laboratory measurements of deep-water breaking waves. Phil. Trans. R. Soc. Lond. A 331 (1622), 735800.Google Scholar
Rojas, G. & Loewen, M. R. 2010 Void fraction measurements beneath plunging and spilling breaking waves. J. Geophys. Res. 115 (C8).Google Scholar
Ryu, Y. & Chang, K.-A. 2008 Green water void fraction due to breaking wave impinging and overtopping. Exp. Fluids 45 (5), 883898.Google Scholar
Ryu, Y., Chang, K. A. & Lim, H. J. 2005 Use of bubble image velocimetry for measurement of plunging wave impinging on structure and associated greenwater. Meas. Sci. Technol. 16, 19451953.Google Scholar
Ryu, Y., Chang, K.-A. & Mercier, R. 2007 Runup and green water velocities due to breaking wave impinging and overtopping. Exp. Fluids 43 (4), 555567.Google Scholar
Saket, A., Peirson, W., Banner, M., Barthelemy, X. & Allis, M. 2017 On the threshold for wave breaking of two-dimensional deep water wave groups in the absence and presence of wind. J. Fluid Mech. 811, 642658.Google Scholar
Skyner, D. 1996 A comparison of numerical predictions and experimental measurements of the internal kinematics of a deep-water plunging wave. J. Fluid Mech. 315, 5164.Google Scholar
Stansby, P. K. & Feng, T. 2005 Kinematics and depth-integrated terms in surf zone waves from laboratory measurement. J. Fluid Mech. 529, 279310.Google Scholar
Stansell, P. & MacFarlane, C. 2002 Experimental investigation of wave breaking criteria based on wave phase speeds. J. Phys. Oceanogr. 32, 12691283.Google Scholar
Svendsen, I. A. 1987 Analysis of surf zone turbulence. J. Geophys. Res. 92 (C5), 51155124.Google Scholar
Thorpe, S. A. 1982 On the clouds of bubbles formed by breaking wind waves in deep water, and their role in air-sea gas transfer. Phil. Trans. R. Soc. Lond. A 304, 155210.Google Scholar
Tian, Z., Perlin, M. & Choi, W. 2008 Evaluation of a deep-water wave breaking criterion. Phys. Fluids 20, 066604.Google Scholar
Tian, Z., Perlin, M. & Choi, W. 2012 An eddy viscosity model for two-dimensional breaking waves and its validation with laboratory experiments. Phys. Fluids 24 (3), 036601.Google Scholar
Ting, F. C. K. 2001 Laboratory study of wave and turbulence velocities in a broad-banded irregular wave surf zone. Coast. Engng 43 (3), 183208.Google Scholar
Ting, F. C. K. & Kirby, J. T. 1994 Observation of undertow and turbulence in a laboratory surf zone. Coast. Engng 24 (1), 5180.Google Scholar
Ting, F. C. K. & Kirby, J. T. 1995 Dynamics of surf-zone turbulence in a strong plunging breaker. Coast. Engng 24 (3), 177204.Google Scholar
Ting, F. C. K. & Kirby, J. T. 1996 Dynamics of surf-zone turbulence in a spilling breaker. Coast. Engng 27 (3), 131160.Google Scholar
Tulin, M. P. 1996 Breaking of ocean waves and downshifting. In Waves and Nonlinear Processes in Hydrodynamics (ed. Grue, J., Gjevik, B. & Weber, J. E.), pp. 177190. Springer.Google Scholar
Zhou, J., Adrian, R. J., Balachandar, S. & Kendall, T. M. 1999 Mechanisms for generating coherent packets of hairpin vortices in channel flow. J. Fluid Mech. 387, 353396.Google Scholar