Author(s): S. Soares Frazao; Y. Zech
Keywords: Dam break; Bend; Physical model; Hydraulic jump; Bore
Abstract: Forecasting the exact velocity and thus the arrival time of a dam-break wave is a key issue of risk assessment, and quite difficult to achieve especially in natural valleys with complex geometry. In this paper, two dam-break experiments are presented, whereby the effects of a sharp bend on the dam-break flow were studied. The laboratory experiments consisted of a dam break in a channel with a respectively 90°an 45°bend and were carried out in the Civil Engineering Department Laboratory of the Universitecatholique de Louvain (UCL, Belgium). The measured flow is compared with a numerical simulation by a Boltzmann finite-volume model, and good agreement is obtained in both the 90°and 45°bend cases. It is then shown how the bend influences the flow, as well upstream and downstream, by means of the dambreak front characteristic. Upstream, the formation of a bore travelling back to the reservoir leads to an important rise of the water level. Downstream, the local slowing of the wave clearly appears, as well as the dependence upon the sharpness of the bend.