VORTICAL VLF MOTIONS UNDER SHORE-NORMAL INCIDENT WAVES
ICCE 2012 Cover Image
PDF

Keywords

Surfzone hydrodynamics
low frequency motions
transient rip currents
surfzone eddies

How to Cite

de Schipper, M. A., Reniers, A., MacMahan, J., & Ranasinghe, R. (2012). VORTICAL VLF MOTIONS UNDER SHORE-NORMAL INCIDENT WAVES. Coastal Engineering Proceedings, 1(33), waves.58. https://doi.org/10.9753/icce.v33.waves.58

Abstract

Field observations and numerical model simulations are examined to investigate the magnitude of vortical very low frequency (VLF) velocity fluctuations (i.e. large scale surfzone eddies) under different offshore wave forcing. Observations of vortical VLF motions under shore -normal wave incidence at Duck, NC, USA are re-analyzed and compared with the characteristics of the incident wave spectrum. Long wave periods and narrow frequency spread incident waves were found to coincide with stronger vortical VLF motions. Numerical model simulations investigating the effect of the incident wave parameters in a more isolated way confirm the observed effect of frequency spread and wave period on the magnitude of VLF motions. Variations in incident wave spectrum resulted in changes in the vortical VLF magnitude of the same order as the magnitude of the vortical VLF velocity fluctuations themselves. These results imply that under shore-normal incident waves strong vortical VLF velocity fluctuations in the surfzone are more likely under swell conditions and at swell dominated coasts.
https://doi.org/10.9753/icce.v33.waves.58
PDF

References

Battjes, J. A., H.J. Bakkenes, T.T. Janssen, and A.R. van Dongeren. 2004. Shoaling of subharmonic gravity waves, J. Geophys. Res., 109.

Bowen, A.J., and R.A. Holman. 1989. Shear Instabilities of the Mean Longshore Current 1. Theory, J. Geophys. Res., 94.

Dalrymple, R.A. 1975. A mechanism for rip current generation on an open coast, J. Geophys. Res., 80.

Elgar, S., R.T. Guza, W.C. O'Reilly, B. Raubenheimer, and T.H.C. Herbers. 2001. Wave energy and direction observed near a pier, J. Waterw. Port Coastal Ocean Eng., 127.

Feddersen, F. 2004. Effect of wave directional spread on the radiation stress: comparing theory and observations, Coastal Engineering, 51.

Guza, R.T., and E.B. Thornton. 1980. Local and Shoaled Comparisons of Sea Surface Elevations, Pressures, and Velocities, J. Geophys. Res., 85.

Holthuijsen, L. H., N. Booij, and T. H. C. Herbers. 1989. A prediction model for stationary short-crested waves in shallow water with ambient currents, Coastal Engineering, 13.

Holthuijsen, L.H. 2007. Waves in oceanic and coastal waters Cambrigde University Press

Johnson, D., and C. Pattiaratchi . 2004. Transient rip currents and nearshore circulation on a swell-dominated beach, J. Geophys. Res., 109.

Kuik, A. J., G. P. van Vledder, and L. H. Holthuijsen. 1988. A method for the routine analysis of pitch-and-roll buoy data, J. Phys. Oceanogr., 18

Long, C. E., and J. Atmadja. 1994. Index and bulk parameters for frequency directional spectra measured at CERC Field Research Facility, September 1990 to August 1991, Misc. Pap. CERC 94-5.

Longuet-Higgins, M.S. and R.W. Stewart, 1962. Radiation stress and mass transport in gravity waves, with application to surf beats. Journal of Fluid Mechanics, 13

MacMahan, J.H., A.J.H.M. Reniers, E.B. Thornton, and T.P. Stanton. 2004. Surf zone eddies coupled with rip current morphology, J. Geophys. Res., 109.

MacMahan, J.H., E.B. Thornton, and A.J.H.M. Reniers. 2006. Rip current review, Coastal Engineering. 53.

MacMahan, J.H., A.J.H.M. Reniers, and E.B. Thornton. 2010. Vortical surf zone velocity fluctuations with 0(10) min period, J. Geophys. Res., 115.

Reniers, A.J.H.M., J.A. Roelvink, and E.B. Thornton. 2004. Morphodynamic modeling of an embayed beach under wave group forcing, J. Geophys. Res., 109.

Reniers, A.J.H.M., J.H. MacMahan, E.B. Thornton, and T.P Stanton. 2007. Modeling of very low frequency motions during RIPEX, J. Geophys. Res., 112.

Reniers, A.J.H.M., J.H. MacMahan, E.B. Thornton, T.P. Stanton, M. Henriquez, J.W. Brown, J.A. Brown, and E. Gallagher. 2009. Surf zone surface retention on a rip-channeled beach, J. Geophys. Res., 114.

Reniers, A.J.H.M., J.H. MacMahan, F.J. Beron-Vera, and M.J. Olascoaga. 2010, Rip-current pulses tied to Lagrangian coherent structures, Geophys. Res. Lett., 37.

Sand, S. E. 1982. Long waves in directional seas, Coastal Enineering., 6.

Spydell, M.S., F. Feddersen, R.T. Guza, and W.E. Schmidt. 2007. Observing surf-zone dispersion with drifters. J. Phys. Oceanogr.,37.

Spydell, M.S., and F. Feddersen. 2009. Lagrangian drifter dispersion in the surf zone: Directionally spread, normally incident waves, J. Phys. Oceanogr., 39.

Van Dongeren, A., A. Reniers, J. Battjes, and I. Svendsen. 2003. Numerical modeling of infragravity wave response during DELILAH, J. Geophys.Res., 108.

van Vledder, G.P. 1992, Statistics of wave group parameters, Proceedings of the International Conference on Coastal Engineering; No 23.

Authors retain copyright and grant the Proceedings right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this Proceedings.