Turbulent shear flows are omnipresent in nature. Examples include oceanic wake flow generated in lee side of islands and jet flows due to effluent discharge into rivers or estuaries. Highly organized large-scale two-dimensional coherent structures are commonly observed in shallow turbulent shear flows. For instance, re-circulating eddies of the size of the island were observed in Rupert Bay in Northern Canada. The vertical length scale Lz of the coherent structures is of the order of water depth, while their horizontal length scale Lx is of the order of size of the free shear layer. These flows are referred to as shallow when their horizontal length scale is much larger than their vertical length scale (Lx＞＞Lz). This paper is devoted to the study of island wakes in shallow water. The study is carried out using a numerical model based on the shallow water equations. The numerical scheme is a conservative finite volume in which the fluxes are obtained from Boltzmann equation in conjunction with the Bhatnagar-Gross-Krook collision model. The numerical model is hereafter referred to as BGK model. The results generated by the BGK model are compared to the experimental data as well as the numerical results shown in other literatures, thus showing the capability and limitation of the BGK model on the study of island wakes in shallow water.
展开▼
