Contents |
Abstract
Suspended sediment transport by drag-affected dam-break flow Dam-break flows are an important type of fluid motion which have received extensive theoretical and experimental study. The motion arises when a vertical barrier separating a fluid layer form an initially dry bed is instantaneously removed and the fluid subsequently intrudes over the bed. This study analyses two aspects of dam-break flow, namely the effects of drag on the motion and the ability of the flow to transport sediment. Provided the flow is sufficiently deep, basal drag is usually neglected, and a simple analytical model of the motion can then be derived. However, close to the front of the flow, where the depth of the moving layer becomes small, it is inappropriate to neglect drag and the flow is strongly modified in this region. In this study, using matched asymptotic expansions, the effects of drag at the front are coupled to the bulk of the flow to elucidate the drag-induced change in the motion. Suspended sediment may be entrained, transported and deposited by dam-break flows over erodible boundaries. In this study a new Lagrangian approach for modelling the advective transport of suspended sediment is developed. This novel analytical framework readily permits the calculation of the concentration of sediment following fluid particles and obviates the need for complex numerical calculations of the concentration field. |