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Title: Vertical turbulence exchange in tidal flows
Author: Shiono, Koji
ISNI:       0000 0004 2721 7648
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1981
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This thesis presents the results of some investigative fieldwork carried out on the Great Ouse Estuary in May and September 1979 under a joint collaborative study between the Hydraulics Research Station (HRS) and the Tidal Waters Research Group, (TWRG) of the Civil Engineering Department, University of Birmingham. The Growing use of mathematical models to solve engineering problems in stratified flows has highlighted the need to understand the basic mechanisms behind the exchange of momentum and solutes through turbulent fluctuations. In this study direct readings of turbulent fluctuations have been obtained in a partially stratified tidal flow. These measurements along with data for the turbulent mean velocity and density fields, have been used. to characterize turbulence, by turbulent parameters, spectral analysis, to evaluate the vertical exchange of momentum and solute, and in particular to examine the mixing length functions of Rossby and Montgomery, and Kent and Pritchard relating to Richardson numbers (Ri) less than 1, when the mixing length is most sensitive to change in the vertical density gradient. The turbulent parameters obtained from the data are in reasonable agreement with appropriate results from atmospheric and laboratory data. The mixing length results based upon direct measurements of turbulence have been used to evaluate the coefficients in the Kent and Pritchard and Rossby and Montgomery equations. These coefficients are applicable up to a gradient Richardson number of 0.6 and clearly show the sensitivity of the turbulent transport mechanisms in the vertical direction to even small values of Ri (^-'0.05). Estimates have been made of some of the coefficients associated with the second order solution to the turbulence closure problem for stratified flows.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available