Two-dimensional depth-averaged modelling of dam-break flows over mobile beds

Abstract

The paper is aimed at the description and validation of a novel two-dimensional depth-averaged simulation tool for highly unsteady discontinuous flows over complex time-evolving geometries. The conceptual model is developed within the shallow-flow framework and features non-equilibrium sediment transport. A fully conservative finite-volume discretization scheme is employed. The treatment of bed-slope source terms ensures that the scheme is well balanced and leads to correct energy losses in discontinuities. Existing laboratory data are used to validate the model and to discuss some of its embedded formulations. Blind-test comparison shows that the model is capable of describing the main dam-break flow and bed morphology features. The solution is shown to be sensitive to the formulations for sediment transport capacity and for adaptation length (Λ). A better functional relation of Λ with the Shields parameter is investigated. The quality of the solution is shown to be only marginally improved by the inclusion of turbulent stresses.