Nonhydrostatic Dam Break Flows. II: One-Dimensional Depth-Averaged Modeling for Movable Bed Flows

Abstract

AbstractThe dam break flow over a movable bed is an important problem in fluvial flow processes. These flows are usually predicted by a one-dimensional (1D) approach based on a hydrostatic pressure distribution. Recent three-dimensional (3D) nonhydrostatic simulations of dam break waves over movable beds based on the Reynolds-averaged Navier-Stokes (RANS) equations revealed that the Saint Venant theory is not accurate in predicting the flow dynamics within the scour hole developed. In this work, a generalized 1D nonhydrostatic model for flow over movable beds is proposed assuming a linear, nonhydrostatic, pressure distribution. The new set of 1D equations accounts for the vertical acceleration, which is important in dam break waves over movable beds given the instantaneous curved beds generated over the erodible terrain. These equations account for both the bed and suspended-load transport modes. A high-resolution finite volume numerical scheme with a semi-implicit treatment of nonhydrostatic terms is dev...