Division of a critical flow at three branch open channel intersection
Division d'un écoulement critique dans une intersection de 3 canaux
Résumé
An experimental study of the characteristics of dividing critical flows in a 90° open-channel junction formed by three horizontal equal-width branches is presented, conducted for various inflow discharges and downstream boundary conditions. Outflow discharges and flow depths were also measured. Four main flow patterns are identified considering the location and length of the hydraulic jumps that develop across the main and lateral channels. A relationship between the discharge division ratio and the tailwater Froude number is found reproducing well the experimental data. Practical applications of this relationship include the design of open channel and pipe networks and one-dimensional numerical modeling of flood propagation in urban areas. The study shows also that a two-dimensional depth-averaged numerical model hardly gives better predictions of the discharge ratios because of the presence of three-dimensional features at the junction.
Une recherche expérimentale sur les caractéristiques d'écoulements critiques se divisant dans une intersection de trois canaux est conduite pour différentes conditions limites. Les caractéristiques expérimentales des écoulements sont indiquées dans les différents types d'écoulements identifiés. La répartition des débits est comparée à une formule analytique et aux résultats d'une modélisation 2D.