In this paper, the results of a benchmark test launched within the framework of the NSF–PIRE project “Modelling of Flood Hazards and Geomorphic\ud
Impacts of Levee Breach and Dam Failure” are presented. Experiments of two-dimensional dam-break flows over a sand bed were conducted at\ud
Université catholique de Louvain, Belgium. The water level evolution at eight gauging points was measured as well as the final bed topography.\ud
Intense scour occurred close to the failed dam, while significant deposition was observed further downstream. From these experiments, a benchmark\ud
was proposed to the scientific community, consisting of blind test simulations, that is, without any prior knowledge of the measurements. Twelve\ud
different teams of modellers from eight countries participated in the study. Here, the numerical models used in this test are briefly presented. The results\ud
are commented upon, in view of evaluating the modelling capabilities and identifying the challenges that may open pathways for further research
Fast geomorphic transients may involve complex scenarios of sediment transport, occurring near the bottom as bed load (i.e., saltating, sliding, and rolling) or as suspended load in the upper portion of the flow. The two sediment transport modalities may even coexist or alternate each other during the same event, especially when the shear stress varies considerably. Modeling these processes is therefore a challenging task, for which the usual representation of the flow as a mixture may result in being unsatisfactory. In the present paper, a new two-phase depth-averaged model is presented that accounts for variable sediment concentration in both bed and suspended loads. Distinct phase velocities are considered for bed load, whereas the slip velocity between the two phases is neglected in the suspended load. It is shown that the resulting two-phase model is hyperbolic, and the analytical expression of the eigenvalues is provided. The entrainment/deposition of sediment between the bottom and the bed load layer is based on a modified van Rijn transport parameter, whereas for the suspended sediment a first-order exchange law is considered. A numerical finite-volume method is used for the simulation of three dam break experiments found in the literature, which are effectively reproduced in terms of both free surface elevation and bottom deformation, confirming the key role played by the solid concentration variability even for two-phase models
The need for further education campaigns, and their consequent evaluations, is relevant. Monitoring sexual behaviour of general population, focusing on risk behaviour rather than risk groups, is fundamental nowadays in preventing HIV.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.