This thesis is mainly concerned with the theoretical prediction of the mass transport velocity in an off-shore tidal current. Other agents that may be responsible for contributions to the existing steady currents are ignored. In the treatment, the fluid system is divided into two regimes a viscous boundary layer, where vertical gradients are considered important and, above this, a region where the motion is, to a first approximation, independent of the depth coordinate. In this uppermost region, the effects of viscosity are neglected. Superimposed on this basic picture, next to the sea-bed, a thin layer is proposed across which there is a rapid transition from laminar to turbulent flow conditions (the laminar sub-layer). Above this layer, the turbulence is assumed to have the same characteristics at all depths, and can be parameterised by using a constant coefficient of eddy-viscosity. The current just above the sea-bed is related to the bottom stress by an empirical quadratic friction law in order to provide an estimate of frictional dissipation. The resulting velocity profiles and the order of magnitude of frictional dissipation at the sea-bed are in good agreement with observation and experiment. A general expression for the horizontal mass transport velocity is derived in the case of constant depth. Using data that is representative of conditions in Liverpool Bay and the eastern Irish Sea, the horizontal mass transport velocity is determined, and it is suggested that the magnitude and direction of this velocity near the bed is closely related to the net movement of any material suspended just above the sea-floor.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:645984 |
| Date | January 1972 |
| Creators | Dyke, Philip P. G. |
| Publisher | University of Reading |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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