Some experiments with a numerical model of circulation and mixing in a tidal estuary
1975; Elsevier BV; Volume: 3; Issue: 3 Linguagem: Inglês
10.1016/0302-3524(75)90029-8
ISSN1878-3023
Autores Tópico(s)Oceanographic and Atmospheric Processes
ResumoA two-dimensional model of estuary circulation, of which a mathematical description has been published previously, has been applied to a study of the changes in circulation and salinity distribution which occur in an estuary of simple geometrical shape when certain parameters of the flow are varied systematically. The estuary is of rectangular cross-section but the width and depth vary along its length. The boundary conditions include a simple harmonic tidal oscillation applied at the mouth and a uniform river discharge at the head of the estuary. Two internal parameters, the coefficients of vertical eddy viscosity and diffusion, Nz and Kz, respectively, have been taken (a) as constants, (b) as functions of the depth of water and the depth-mean current, and hence varying with time, and (c) as functions also of the Richardson number. It was found that the use of variable coefficients, Nz and Kz, instead of constant values, had a considerable effect on the vertical profiles of current and salinity during a tidal period and gave a representation closer to observational data. Experimental runs with different values of the tidal amplitude, the river flow and end salinities being kept constant, showed the effects of interaction between the tidal-driven and density-driven components of the flow. Other runs were made with varying river discharge and horizontal salinity gradients. It is considered that the results of these tests will be useful in the application of similar models to real estuaries.
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