Simulation of supercritical flow in crossroads: Confrontation of a 2D and 3D numerical approaches to experimental results
Résumé
This work deals with the modeling of a flood in an urban environment. Among the various types of urban flood events, it was decided to study specifically the severe surface flooding events, which take place in highly urbanized areas. This work concerns particularly the numerical resolution of the two-dimensional Saint Venant equations for the study of the propagation of flood through the crossroads in the city. A discontinuous finite-element space discretization with a second-order Runge-Kutta time discretization is used to solve the two-dimensional Saint Venant equations. The scheme is well suited to handle complicated geometries and requires a simple treatment of boundary conditions and source terms to obtain high-order accuracy. The explicit time integration, together with the use of orthogonal shape functions, makes the method for the investigated flows computationally more efficient than comparable second-order finite volume methods. The scheme is applied to several supercritical flows in crossroads, which are investigated by Mignot. The experimental results obtained by the author are used to verify the accuracy and the robustness of the method. The results obtained are compared to those obtained by a second-order finite volume method (Rubar20 (2D)) and by FLUENT (3D). A very good agreement between the numerical solution obtained by the Runge-Kutta discontinuous Galerkin (RKDG) method and the experimental measured data were found. The method is then able to simulate the flow patterns observed experimentally and able to predict well the water depths, the discharge distribution in the downstream branches of the crossroad and the location of the hydraulic jumps and other flow characteristics more than the other methods.
Mots clés
Urban floods
Urbanized areas
Water depths Engineering main heading: Two dimensional
Engineering controlled terms: Boundary value problems
Experiments
Finite volume method
Flow patterns
Flow simulation
Function evaluation
Galerkin methods
Hydraulics
Numerical analysis
Runge Kutta methods
Three dimensional
Three term control systems Engineering uncontrolled terms: Discontinuous galerkin
Element spaces
Explicit time integrations
Finite volumes
Flow characteristics
Measured datums
Numerical approaches
Numerical resolutions
Numerical solutions
Shape functions
Source terms
Supercritical flows
Time discretization
Urban environments