Circulation of large water bodies caused by aerator

Siew Tong, Ling (2006) Circulation of large water bodies caused by aerator. PhD thesis, University of Liverpool.

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Abstract

Aerators had always been widely used for vanous purposes. The scale of the applications ranged from household fish tanks to water treatment plants. It was also applied to re-circulate large water body reservoirs, which this thesis aimed to address. Despite the wide application, the hydrodynamic theories of the flows created as a result of .air bubble plume application were still not totally validated. Therefore experimental results from past researches and from the present studies were used to validate the mathematical model of Goossens et ai's [1979,1980,1982], Fannelop et ai's [1980, 1991], in which the accuracy of the models were found to be less accurate than claimed in the publications. Through the experiments conducted, valuable results were obtained. These results were not only applied for numerical model validations mentioned above, but also used to clarify the physical characteristic of the circulations. Through these experiments, it was found that the secondary circulation do contribute to the overall mixing process, but in a slower process. The dye injected to trace the physical circulations was detected using the dye concentration detector known as SCUFA, in which the data were utilized to determine the concentration dispersion coefficient caused by the aeration. A commercial CFD software known as FLUENT was applied to model the case of aeration in both the homogenous and stratified conditions. Investigations were carried out systematically to determine suitable settings for the simulation. Experimental results obtained from the present study and from other published researches were used to verify and validate the CFD model. The results from the CFD model were compared with the experimental results through the vertical velocity profile, horizontal velocity profile and the overall circulation pattern. A verified and validated CFD model of the bubble aeration in the homogenous was obtained, in which the vertical velocity profile within the bubble plume, the horizontal outflow velocity profile and the overall circulation pattern can be accurately simulated. However, the simulation of the stratified conditions reqUIres a more complex procedure, in which the surface boundary condition has resulted in various inaccurate simulations. A 'Used Defined Function' was subsequently created to deal with the problem. A working FLUENT model for the stratified condition was successfully created in the end and the simulated results were validated with experimental results.

Item Type:	Thesis (PhD)
Depositing User:	Symplectic Admin
Date Deposited:	20 Oct 2023 12:40
Last Modified:	20 Oct 2023 13:00
DOI:	10.17638/03174632
Copyright Statement:	Copyright © and Moral Rights for this thesis and any accompanying data (where applicable) are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge.
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3174632