Author(s): Yann Ourmiéres; Dominique Mouazé

Linked Author(s):

Keywords: Wave-induced flow; flat bed; rippled bed; wave flumes; LDV; 2D model; Stokes drift

Abstract: The wave-induced boundary layer flow over a rippled bed is studied. A two-dimensional model aiming to solve the flow in the vicinity of the bed has been developed. First the model is tested for a flat bed case and comparison is made with experimental data obtained by laser Doppler velocimetry (LDV) in two wave flumes presenting different characteristics. As the numerical and experimental results are compared, particular attention is given to the mean Eulerian velocity profiles calculated from the two sources and the theoretical solution from Longuet-Higgins [Philos. Trans. Roy. Soc. Lond. A 245 (1953) 535]. Discrepancies are explained and the use of the available theory is discussed. The numerical model is then adapted to a rippled bed case and compared to experimental data obtained by LDV in a wave flume fitted with a rippled bed. The dynamical consistency of the model is tested and the appearance of a vortex created at each half-wave cycle is shown. Mean velocity profiles are plotted at different locations along the ripple profile. Different types of profile are obtained depending on the location. Mean velocity profiles from the model are studied for other flow and ripple conditions and it is shown that the profiles located at mid-distance between the crest and the trough always featured negative overshoot amplitude while the profiles located above the crest and the trough could be of either sign. An example of flow visualizations is also shown and qualitative comparisons are made with the numerical model run for a similar case.

DOI: https://doi.org/10.1080/00221686.2007.10525039

Year: 2007