Author(s): Daisuke Kobayashi; Tatsuhiko Uchida; Yoshihisa Kawahara
Linked Author(s): Tatsuhiko Uchida, Yoshihisa Kawahara
Keywords: Breaking bore; Shallow water equation; Three-dimensionality
Abstract: Tsunami run-up in rivers can be classified into two forms: breaking bore and undular bore. In this study, focusing on the breaking bore, we investigated hydraulic bore propagations by rapidly opening a gate installed in a straight and meandering channel. We measured the temporal variations in wave height and compared the experimental results and calculation results in the straight and meandering channels with the aim of clarifying the characteristics of bore propagation. We generated the two type of bores in our experiment; Type 1 is the breaking bore with downstream water depth close to dry, Type 2 is the breaking bore on wet bed. We calculated the bore propagation in the meandering channel using a two-dimensional shallow water equation. By comparing the wave height of the meandering channel in the calculation and the experiment results, we found that the two- dimensional calculation results of the breaking bore can substantially express the wave height variations of Type 2 in a meandering channel. On the other hand, it was investigated on the Type 1 breaking bore in the meandering channel that some waves propagated to upstream direction under supercritical flow condition due to the reflection from the side bank that cannot be reproduced by the shallow water equation.
Year: 2020