A NON-HYDROSTATIC NUMERICAL MODELLING OF EXCHANGE FLOWS

摘要

Stratified exchange flows are investigated by a three-dimensional, non-hydrostatic, numerical model with a free surface. The model is based on 3D Reynolds-averaged Navier-Stokes equations under the Boussinesq assumption. The model equations are written in a generalized vertical coordinate system and with orthogonal curvilinear horizontal coordinates. A mode splitting technique, decomposition of pressure and velocity fields into hydrostatic and non-hydrostatic components and sequential calculation of these components are the base of numerical algorithm of the model. The model was tested against a laboratory experiment on the exchange flow through long and narrow strait and was applied to simulate the water exchange through the Strait of Dardanelles. It reproduces the complicated three-dimensional structures of currents in the Dardanelles. It also shows that mixing plays a crucial role in maintaning the observed exchange flow between the Aegean and Marmara seas.