Observations of turbulence within the surf and swash zone of a field-scale sandy laboratory beach

Type Article
Date 2016-07
Language English
Author(s) Brinkkemper J. A.1, Lanckriet T.2, Grasso FlorentORCID3, Puleo J. A.2, Ruessink B. G.1
Affiliation(s) 1 : Univ Utrecht, Fac Geosci, Dept Phys Geog, Inst Marine & Atmospher Res, POB 80-115, NL-3508 TC Utrecht, Netherlands.
2 : Univ Delaware, Dept Civil & Environm Engn, Ctr Appl Coastal Res, Newark, DE 19716 USA.
3 : IFREMER, Ctr Bretagne, Dyneco Physed, BP70, F-29280 Plouzane, France.
Source Coastal Engineering (0378-3839) (Elsevier Science Bv), 2016-07 , Vol. 113 , P. 62-72
DOI 10.1016/j.coastaleng.2015.07.006
WOS© Times Cited 25
Note SI : Barrier Dynamics Experiment II: sediment processes across a large-scale sand barrier
Keyword(s) Turbulence, Plunging breakers, Swash, Laboratory experiment
Abstract Current coastal-evolution models generally lack the ability to accurately predict bed level change in shallow (<~2 m) water, which is, at least partly, due to the preclusion of the effect of surface-induced turbulence on sand suspension and transport. As a first step to remedy this situation, we investigated the vertical structure of turbulence in the surf and swash zone using measurements collected under random shoaling and plunging waves on a steep (initially 1:15) field-scale sandy laboratory beach. Seaward of the swash zone, turbulence was measured with a vertical array of three Acoustic Doppler Velocimeters (ADVs), while in the swash zone two vertically spaced acoustic doppler velocimeter profilers (Vectrino profilers) were applied. The vertical turbulence structure evolves from bottom-dominated to approximately vertically uniform with an increase in the fraction of breaking waves to ~ 50%. In the swash zone, the turbulence is predominantly bottom-induced during the backwash and shows a homogeneous turbulence profile during uprush. We further find that the instantaneous turbulence kinetic energy is phase-coupled with the short-wave orbital motion under the plunging breakers, with higher levels shortly after the reversal from offshore to onshore motion (i.e. wavefront).
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