Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664716
Title: Numerical and experimental modelling of dam break interaction with a sediment bed
Author: McMullin, Nicholas
ISNI:       0000 0004 5365 3646
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2015
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Abstract:
A dam break event is considered, taking place over a uniform sediment bed. Understanding and modelling the erosion that occurs when the fluid behind the dam collapses at release has important applications in coastline morphodynamics / beach erosion modelling. A new coupled two dimensional Navier-Stokes solver and sediment transport model is presented with novel methods for dealing with non-converging solutions to the Navier-Stokes equations and a new adaptation to the Youngs [1982] volume-of-fluid reconstruction scheme. The implementation of a sediment transport model includes a new method for accounting for mass conservation for the transition of sediment between bed and flow as well as a novel method for accounting for the redistribution of material associated with the maintenance of the critical angle of repose or slope limit. The model is validated and then applied to a dam break simulation for various backwater and tailwater conditions. Classical experimental realizations of dam break events have involved the rapid removal of a barrier in a flume [e.g. [Levin, 1952; Dressler, 1954; Bell et al., 1992])]. However, early-time flow analysis encounters two problems with this method. Firstly, the removal of the barrier creates a strong vortex sheet on the face of the static fluid immediately behind the barrier that is not present in either the idealized problem, or the motivating environmental problems. Secondly, the removal of the barrier cannot take place instantaneously and so a brief jet-like flow is initially induced through the opening between the base of the barrier and the sediment layer. We partially circumvent these difficulties with the classical experiments by implementing a novel dam break barrier release, using a barrier similar to the wrapped-fabric design of [Dalziel, 1993], which minimizes the initial vortical disturbance. Three-dimensional stereoscopic Particle Image Velocimetry (PIV) measurements allow us not only to capture the velocity field in the laser-plane, but also perpendicular to it. These planar experimental results are compared to the results of the numerical study and the comparison is shown to be good while the simulation successfully converges.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.664716  DOI: Not available
Keywords: TC Hydraulic engineering. Ocean engineering
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