☆ 4.7 Article

RANS v2-f simulation of a swash event: Detailed flow structure

COASTAL ENGINEERING (2013)

Journal

COASTAL ENGINEERING

Volume 71, Issue -, Pages 1-12

Publisher

ELSEVIER SCIENCE BV

DOI: 10.1016/j.coastaleng.2012.07.001

Keywords

Swash flow; Numerical simulation; RANS v(2)-f turbulence model; Aeration; Flow reversal; Bed shear stress

Categories

Engineering, Civil Engineering, Ocean

Funding

Aquitaine region, France

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Protocol

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Reagent

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Abstract

The flow structure of a swash event over a uniform slope is studied using a RANS-VOF numerical model coupled with a v(2)-f turbulence closure. The model is compared with experimental data of recent laboratory experiments. The ability of the turbulence modelling for simulating swash flow and the evolution of the computed bed shear stress during run-up and run-down are investigated. The agreement between numerical results and measured data, such as water depth, depth-averaged velocity and bed shear stress is very good during run-up. Main discrepancies are found during run-down. The paper also examines the aeration of the water layer in the swash flow, taking advantage of the PLIC method for computing the air-water interfaces. Air is continuously entrapped in the swash front and released at its rear during run-up. A detailed analysis indicates that the flow reversal is initiated near the bottom at the outer boundary of the swash zone and progresses landward. The study highlights the asymmetry between run-up and run-down. During run-up, the swash front propagation determines the turbulence properties and the bed shear stress profile on the beach, whereas the flow properties are more homogeneously distributed in the swash area during run-down. (c) 2012 Elsevier B.V. All rights reserved.

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