A numerical investigation into the dynamics of a partially-mixed estuary
A numerical investigation into the dynamics of a partially-mixed estuary
The physical oceanography of a narrow, partially-mixed estuarine channel (Southampton Water and Test Estuary) has been studied in terms of its circulation and mixing patterns, using in-situ data and numerical model results. Tidal resonance effects and dissipation rates of the tidal energy were computed for the various constituents of the propagating tidal wave, presenting the enhanced effect of the M4 and M6-components on the overall tidal behaviour. Direct observations and past data-sets were used to describe the velocity and salinity fields in a longitudinal-vertical direction, and to prescribe accurately the most representative conditions imposed at its boundaries. An analysis of the residual longitudinal and lateral currents and fluxes of water and salt illustrated the importance of river flow discharge and wind shear stress on the tidally-mean transport. The Stokes drift mechanism transports water and salt in the upstream direction, having an increasing magnitude under spring tidal conditions. Lateral Eulerian currents were found to the same order of magnitude as the longitudinal ones, but with smaller values, especially under spring tidal amplitudes, under which the flow coincides better with the main estuarine axis. Vertical eddy coefficients of viscosity and diffusivity were calculated using direct observations and semi-empirical arguments, and their range of variation within the tidal cycle was defined. Well-mixed conditions were found to exist during most of the tidal cycle at the lower parts of the estuary, with the stratification effects being important at the upper estuary.
A series of computational tests examined the response of the developed two-dimensional laterally-averaged numerical model on a hypothetical channel, under different boundary forcings. Various formulations of Kz, Nz were tested, but the use of local stability function (Richardson Number) produced realistic salinity and velocity profiles in a simple and economic way, considering also the appropriate physical processes of turbulent mixing.
University of Southampton
1994
Sylaios, Georgios
(1994)
A numerical investigation into the dynamics of a partially-mixed estuary.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The physical oceanography of a narrow, partially-mixed estuarine channel (Southampton Water and Test Estuary) has been studied in terms of its circulation and mixing patterns, using in-situ data and numerical model results. Tidal resonance effects and dissipation rates of the tidal energy were computed for the various constituents of the propagating tidal wave, presenting the enhanced effect of the M4 and M6-components on the overall tidal behaviour. Direct observations and past data-sets were used to describe the velocity and salinity fields in a longitudinal-vertical direction, and to prescribe accurately the most representative conditions imposed at its boundaries. An analysis of the residual longitudinal and lateral currents and fluxes of water and salt illustrated the importance of river flow discharge and wind shear stress on the tidally-mean transport. The Stokes drift mechanism transports water and salt in the upstream direction, having an increasing magnitude under spring tidal conditions. Lateral Eulerian currents were found to the same order of magnitude as the longitudinal ones, but with smaller values, especially under spring tidal amplitudes, under which the flow coincides better with the main estuarine axis. Vertical eddy coefficients of viscosity and diffusivity were calculated using direct observations and semi-empirical arguments, and their range of variation within the tidal cycle was defined. Well-mixed conditions were found to exist during most of the tidal cycle at the lower parts of the estuary, with the stratification effects being important at the upper estuary.
A series of computational tests examined the response of the developed two-dimensional laterally-averaged numerical model on a hypothetical channel, under different boundary forcings. Various formulations of Kz, Nz were tested, but the use of local stability function (Richardson Number) produced realistic salinity and velocity profiles in a simple and economic way, considering also the appropriate physical processes of turbulent mixing.
This record has no associated files available for download.
More information
Published date: 1994
Identifiers
Local EPrints ID: 462855
URI: http://eprints.soton.ac.uk/id/eprint/462855
PURE UUID: c1d6aa93-093f-4f5c-b773-c1c0197a5db4
Catalogue record
Date deposited: 04 Jul 2022 20:16
Last modified: 04 Jul 2022 20:16
Export record
Contributors
Author:
Georgios Sylaios
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics