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Robustness of nearshore vortices

Published online by Cambridge University Press:  09 July 2018

James C. McWilliams Open the ORCID record for James C. McWilliams [Opens in a new window] ,
Cigdem Akan  and
Yusuke Uchiyama
James C. McWilliams*
Affiliation:
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095-1565, USA
Cigdem Akan
Affiliation:
College of Computing, Engineering and Construction, University of North Florida, Jacksonville, FL, USA
Yusuke Uchiyama
Affiliation:
Department of Civil Engineering, Kobe University, Kobe, Japan
*
†Email address for correspondence: jcm@atmos.ucla.edu
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Abstract

Coherent vortices with horizontal swirl arise spontaneously in the wave-driven nearshore surf zone. Here, a demonstration is made of the much greater robustness of coherent barotropic dipole vortices on a sloping beach in a 2D shallow-water model compared with fully 3D models either without or with stable density stratification. The explanation is that active vortex tilting and stretching or instability in 3D disrupt an initially barotropic dipole vortex. Without stratification in 3D, the vorticity retains a dipole envelope structure but is internally fragmented. With stratification in 3D, the disrupted vortex reforms as a coherent but weaker surface-intensified baroclinic dipole vortex. An implication is that barotropic or depth-integrated dynamical models of the wave-driven surf zone misrepresent an important aspect of surf-eddy behaviour.

JFM classification

Geophysical and Geological Flows: Topographic effects Vortex Flows: Vortex dynamics Vortex Flows: Vortex Flows
Type
JFM Rapids
Information
Journal of Fluid Mechanics , Volume 850 , 10 September 2018 , R2
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Copyright
© 2018 Cambridge University Press 

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References

Arthur, R. S. 1962 A note on the dynamics of rip currents. J. Geophys. Res. 67, 2777–2779.Google Scholar
Bowen, A., Inman, D. & Simmons, V. 1968 Wave set-down and set-up. J. Geophys. Res. 73, 2569–2577.Google Scholar
Centurioni, L. R. 2002 Dynamics of vortices on a uniformly shelving beach. J. Fluid Mech. 472, 211–228.Google Scholar
Dalyrimple, R. A., MacMahan, J. H., Reiners, A. J. & Nelko, V. 2011 Rip currents. Annu. Rev. Fluid Mech. 43, 551–581.Google Scholar
Dauhajre, D., McWilliams, J. C. & Uchiyama, Y. 2017 Submesoscale coherent structures on the continental shelf. J. Phys. Oceanogr. 47, 2949–2976.Google Scholar
Duran-Matute, M., Albagnac, J., Kamp, L. P. J. & van Heijst, G. J. F. 2010 Dynamics and structure of decaying shallow dipolar vortices. Phys. Fluids 22, 116606.Google Scholar
Feddersen, F. 2014 The generation of surfzone eddies in a strong alongshore current. J. Phys. Oceanogr. 44, 600–617.Google Scholar
Haller, M. C. & Dalrymple, R. A. 2001 Rip current instabilities. J. Fluid Mech. 433, 161–192.Google Scholar
van Heijst, G. J. F. 2014 Shallow flows: 2d or not 2d? Environ. Fluid Mech. 14, 945–956.Google Scholar
Kirby, J. T. & Derakhti, M. 2018 Short-crested wave breaking. Eur. J. Mech. B (in press).Google Scholar
Kumar, N. & Feddersen, F. 2017 The effect of Stokes drift and transient rip currents on the inner shelf. Part II. With stratification. J. Phys. Oceanogr. 47, 243–260.Google Scholar
Kumar, N., Voulgaris, G., Warner, J. C. & Olabarrieta, M. 2012 Implementation of the vortex force formalism in the coupled ocean–atmosphere–wave–sediment transport (COAWST) modeling system for inner shelf and surf zone applications. Ocean Model. 47, 65–95.Google Scholar
Lamb, H. 1932 Hydrodynamics. Dover.Google Scholar
Lentz, S. J. & Fewings, M. R. 2012 The wind- and wave-driven inner-shelf circulation. Annu. Rev. Mar. Sci. 4, 317–343.Google Scholar
Longuet-Higgins, M. S. 1970 Longshore currents generated by obliquely incident sea waves. J. Geophys. Res. 75, 6778–6801.Google Scholar
Marchesiello, P., Benshilat, R., Almar, R., Uchiyama, Y., McWilliams, J. C. & Shchepetkin, A. F. 2015 On tridimensional rip current modeling. Ocean Model. 96, 36–48.Google Scholar
Marmorino, G. O., Smith, G. B. & Miller, W. D. 2013 Infrared remote sensing of surf-zone eddies. IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens. 6, 1710–1718.Google Scholar
McWilliams, J. C., Restrepo, J. M. & Lane, E. M. 2004 An asymptotic theory for the interaction of waves and currents in coastal waters. J. Fluid Mech. 511, 135–178.Google Scholar
Newberger, P. A. & Allen, J. S. 2007 Forcing a three-dimensional, hydrostatic, primitive-equation model for application in the surf zone: 2. Application to Duck94. J. Geophys. Res. 112, C08019.Google Scholar
Oltman-Shay, J. P., Howd, P. A. & Birkemeier, W. A. 1989 Shear instabilities of the mean longshore current: 2. Field observations. J. Geophys. Res. 94, 18031–18042.Google Scholar
Pierrehumbert, R. T. 1986 Universal short-wave instability of two-dimensional eddies in an inviscid fluid. Phys. Rev. Lett. 57, 2157–2159.Google Scholar
Shchepetkin, A. F. & McWilliams, J. C. 2009 Computational kernel algorithms for fine-scale, multi-process, long-term oceanic simulations. In Handbook of Numerical Analysis: Computational Methods for the Ocean and the Atmosphere (ed. Temam, R. & Tribia, J.), vol. 14, pp. 121–183. Elsevier.Google Scholar
Spydell, M. S. & Feddersen, F. 2009 Lagrangian drifter dispersion in the surf zone: directionally spread normally incident waves. J. Phys. Oceanogr. 39, 809–830.Google Scholar
Trefethan, L. N., Trefethan, A. E., Reddy, S. C. & Driscoll, T. A. 1993 Hydrodynamic stability without eigenvalues. Science 261, 578–584.Google Scholar
Uchiyama, Y., McWilliams, J. C. & Akan, C. 2017 Three-dimensional transient wave-driven currents: low-frequency variability in alongshore and rip currents. J. Geophys. Res. 122, C22370.Google Scholar
Uchiyama, Y., McWilliams, J. C. & Shchepetkin, A. F. 2010 Wave–current interaction in a three-dimensional circulation model with a vortex force formalism: application to the surf zone. Ocean Model. 34, 16–35.Google Scholar
Voropayev, S. I., Fernando, H. J. S. & Morrison, R. 2008 Dipolar eddies in a decaying stratified turbulent flow. Phys. Fluids 20, 026602.Google Scholar