A finite element model for the hydrodynamics of shallow tidal basins based on coupling of 2d and 1d elements

This paper describes a finite element model for shallow water flows in which two-dimensional elements are coupled with one-dimensional elements. The resulting 2D-1D model is a powerful and accurate tool to study the hydrodynamics of shallow tidal basins which are crossed by a very intricate network of channels generally departing from the inlets. Examples of such a type of basins are given by most of the lagoons along the North-Adriatic coast, the most famous of which is the Venice lagoon. In the model, two-dimensional elements describe the flow over shallow areas, while one-dimensional elements are used to discretize the channels. The main advantages of the proposed model are represented by both a reduced computational effort, when compared with fully two-dimensional models of comparable grid size, and a greater accuracy in describing the channels geometry. The model was extensively tested against a fully two-dimensional model, and a few examples are presented in the paper. A good agreement between results of the above two models was always found confirming the remarkable capability of the proposed model to account for the presence of deep channels in an otherwise shallow basin.