Mixing parameterization: Impacts on rip currents and wave set-up
| Type | Article | ||||||||||||
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| Date | 2014-07 | ||||||||||||
| Language | English | ||||||||||||
| Author(s) | Bennis Anne-Claire1, 2, 3, Dumas Franck2, Ardhuin Fabrice 4, Blanke Bruno3 |
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| Affiliation(s) | 1 : CNRS UCBN UR, UMR 6143, M2C, F-14000 Caen, France. 2 : IFREMER, DYNECO PHYSED, F-29280 Plouzane, France. 3 : CNRS Ifremer IRD UBO, UMR 6523, LPO, F-29200 Brest, France. 4 : IFREMER, LOS, F-29280 Plouzane, France. |
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| Source | Ocean Engineering (0029-8018) (Pergamon-elsevier Science Ltd), 2014-07 , Vol. 84 , P. 213-227 | ||||||||||||
| DOI | 10.1016/j.oceaneng.2014.04.021 | ||||||||||||
| WOS© Times Cited | 12 | ||||||||||||
| Keyword(s) | Bottom friction, Vertical mixing, Wave set-up, Nearshore processes | ||||||||||||
| Abstract | Wave set-up is often underestimated by the models (e.g. Raubenheimer et al., 2001). Our paper discusses how the wave set-up may be changed by the inclusion of turbulent mixing in the bottom shear stress. The parameterization developed in Mellor (2002) for phase-averaged oscillatory boundary layer is used for this purpose. Two studies are carried out. The dependence of the parameterization on the vertical discretization and on the magnitude of the near-bottom wave orbital velocity is investigated. The function that distributes the turbulent terms over the vertical is modified, giving a good agreement with the average of the phase-resolved velocities, but an overestimation of the turbulent phase-resolved velocities. Applying that parameterization to simulate laboratory conditions in the presence of rip currents gives accurate magnitudes of the rip velocity, particularly in a fully coupled wave–current configuration, with an RMS error of about 4%. Compared to a model using the more standard Soulsby (1995) parameterization, the wave set-up is increased by about 12% when using the alternative parameterization. Thus the bottom shear stress is sensitive to the mixing parameterization with a possible effect of turbulence on the wave set-up. Further measurement and parameterization efforts are necessary for practical applications. | ||||||||||||
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