Resumo

SABAT, Ignacio; LINK, Oscar  e  ETTMER, Bernd. Flow Caused by Dam Breaks: Numerical Modeling Analysis. Tecnol. cienc. agua [online]. 2015, vol.6, n.1, pp.05-23. ISSN 2007-2422.

The finite volumes method is applied to solve 2D Saint Venant equations with source terms that determine runoff of shallow water, in order to calculate flows caused by dam breaks. The model is verified by calculating six cases with known solutions: (1) establishing normal flow based on a horizontal free surface; (2) establishing flow that is gradually varied in a channel with changes in roughness; (3) runoff over an obstacle; (4) formation of an oblique hydraulic jump; (5) damped oscillation of a free surface in a parabolic section; (6) runoff from the breaking of a circular dam and (7) runoff from the partial breaking of a dam. The model is applied to simulate the flow caused by the instantaneous breaking of dams in order to analyze the effect of the joint geometric configuration of the dam, reservoir, valley and channel on the outflow hydrograph. A total of 28 scenarios were simulated for a valley with a parabolic section and a channel with a trapezoidal section, in which the height and position of the dam wall were varied as well as the gap width, length of the slope and roughness of the channel downstream. The results obtained show that the height of the dam is the variable that has the largest effect on the peak flow of the outflow hydrograph and the gap width has a large effect on partial breaks. The roughness of the bed considerably mitigates the peak flow downstream and increases flood time. The position of the mural and the length of the slope have a smaller effect on floods caused by dam breaks. The model developed adequately predicts the complex behavior of the flow caused by the instant breaking of a dam and is therefore a simulation tool with predictive capabilities.

Palavras-chave : Dam break; Saint Venant 2D equations; computational hydraulics; shock capturing conditions.