A MODEL STUDY OF TIDAL AND RESIDUAL FLOW IN DELAWARE BAY AND RIVER

A numerical model, along with existing held data, is used in an explor atory study of the dynamics of Delaware Bay and River. A three-dimensi onal hydrodynamic model has been constructed using a finite element di scretization in space and a harmonic representation in time. These cho ices allow for adequate resolution of geometric and flow features but still allow an efficient numerical solution. The nodes in the horizont al are arranged into triangular elements, and the nodes in the vertica l are transformed into a terrain-following coordinate system. The node s in the vertical are arranged logarithmically from the bottom so that the model resolves' the bottom boundary layer. This paper focuses on the hydrodynamics rather than the salt dynamics. The model results are sensitive to stratification and to the details of the time dependence of the vertical eddy viscosity, A(v). After consideration of several processes, it was found that the stratification effects arise from the tidal straining of the vertical density profile by the velocity. A ha rmonic expansion of A(v) indicates that the frictional effects of a ti me-varying vertical viscosity are more pronounced on the secondary con stituents (S-2, N-2, O-1, K-1) than the dominant constituent (M-2) Thu s the ratio of the amplitude of the secondary constituents to the ampl itude of the primary constituent provides a sensitive measure for comp arison with field data. This comparison places constraints on the vari ability of A(v).