Three-dimensional numerical simulation of wind-driven flows in closed channels and basins

Abstract

In the paper, a fully 3D finite-volume numerical model is developed and employed for the prediction of wind-induced flows in a regular channel and in a square basin with a complex bathymetry. Numerical results are compared with laboratory experiments. Numerical tests are then performed to investigate whether simplifying assumptions about the pressure distribution and the turbulente stresses representation can be employed in the simulation of wind-driven flows. The hydrostatic pressure assumption, resulting in the use of "quasi-3D" models, proved to be reasonably acceptable in order to obtain the vertical profile of the streamwise velocity component away from the boundaries. The quasi-3D model employed, nevertheless, provided incorrect velocity patterns near the upwind and downwind boundaries. The zero-equation turbulence model proposed by Tsanis [J. Hydraul. Div. ASCE 115 (1990) 1113] is also investigated by comparing the parabolic vertical profiles of the eddy viscosity coefficient assumed in this model with those obtained with a more refined k-epsilon model. The eddy viscosity coefficient obtained with the latter is in good agreement with the Tsanis' parabolic assumption in the most part of the studied domains. A strong overestimation of the eddy viscosity was however observed again at the upwind and downstream boundaries of the domains.