Author(s): Davide Wuthrich; Dorette Regout

Linked Author(s): Davide Wüthrich

Keywords: Dam-break wave; Conductivity probe; Air-water flow properties; Sensitivity analysis

Abstract: Dam-break waves, induced by the failure of a dam, result in destructive flood waves with a rapid increase in water level and high wave front celerities. These events pose significant threats to downstream communities, which means that understanding their dynamics is crucial for effective disaster management and mitigation. This study used an experimental approach to investigate the multiphase nature of dam-break waves across two different scales. An array of phase detection (conductivity) probes was used to sample the flow at 13 elevations within the bore and for 4 flow conditions. Each test was repeated at least 50 times, which allowed to compute the main air-water flow properties through an ensemble statistical approach. Results focused on the effect of the air-water threshold on the main air-water features, including void fraction, number of interfaces and bubble chord time. Results revealed that the number of interfaces is significantly influenced by the air-water threshold, while the void fraction and bubble characteristics showed lesser sensitivity to the threshold. More specifically, data pointed out that the use of a 50% threshold underestimated the number of bubbles, favouring the use of a 80% threshold, in line with some previous studies. In addition, the study emphasized the importance of large datasets for precise estimation of air-water flow properties in highly unsteady flows, contributing to a deeper understanding of dam-break waves, in support of the design of safer and more resilient structures.

DOI: https://doi.org/10.3929/ethz-b-000675921

Year: 2024