Experimental Study on Dam-Break Hydrodynamic Characteristics Under Different Conditions

In this study, a series of dam-break experiments was carried out to investigate the influence of the initial downstream water depth, water head settings, and upstream reservoir length on the dam-break wave movement. The instantaneous water level and flow velocity were measured at two specified downstream locations. Considering the requirements for precise data measurement with high temporal resolution, the synchronization of different instruments was realized based on high-speed camera recording. Even with the same initial water head setting, the water level and flow velocity variations of the dam-break wave propagating downstream on the wet bed show noteworthy differences in flow characteristics compared to the initial dry bed, caused by the interactions between the upstream and downstream water. Hydrodynamic formulae proposed by Lauber and Hager (1998) [1] are not applicable for the wet-bed condition, although their solution of wave profiles for the initial dry-bed condition performs well at the location farther from the gate. The non-dimensional average front velocity of the wet-bed condition, which mainly depends on the initial water head setting, is smaller than that of the dry-bed case. In addition, the maximum water level and flow velocity at the downstream location are mainly controlled by the initial water head setting, while the duration of the large values is influenced by the reservoir length.