R Vacondio

SPH Modeling of Shallow Flow with Open Boundaries for Practical Flood Simulation

AbstractA smoothed particle hydrodynamics (SPH) numerical model for shallow water equations (SWEs) is presented for simulating flood inundation owing to rapidly varying flow, such as dam breaks, tsunamis, and levee breaches. Important theoretical and numerical developments have recently been made, and the model in this paper incorporates these developments and implements open boundary conditions, resulting in a general, accurate computational tool suitable for practical application. The method is attractive for flood simulation over large domains in which the extent of inundation is unknown because computation is carried out only in wet areas and is dynamically adaptive. The open boundary algorithm is very general, on the basis of a simplified version of the characteristics method, handling both supercritical and subcritical inflow and outflow. This is tested against reference solutions for flows over a hump involving shocks. The model is then applied to two very different flood inundations resulting from...

GPU-enhanced Finite Volume Shallow Water solver for fast flood simulations

Abstract In this paper a parallelization of a Shallow Water numerical scheme suitable for Graphics Processor Unit (GPU) architectures under the NVIDIA™s Compute Unified Device Architecture (CUDA) framework is presented. In order to provide robust and accurate simulations of real flood events, the system features a state-of-the-art Finite Volume explicit discretization technique which is well balanced, second order accurate and based on positive depth reconstruction. The model is based on a Cartesian grid and boundary conditions are implemented by means of the implicit local ghost cell approach, which enables the discretization of a broad spectrum of boundary conditions including inflow/outflow conditions. A novel and efficient Block Deactivation Optimization procedure has also been adopted, in order to increase the efficiency of the numerical scheme in the presence of wetting-drying fronts. This led to speedups of two orders of magnitude with respect to a single-core CPU. The code has been validated against several severe benchmark test cases, and its capability of producing accurate fast simulations (with high ratios between physical and computing times) for different real world cases has been shown.

A non-uniform efficient grid type for GPU-parallel Shallow Water Equations models

A GPU-parallel numerical model for the solution of the 2D Shallow Water Equations, based on a novel type of grid called Block-Uniform Quadtree (BUQ), is presented. BUQ grids are based on a data structure which allows to exploit the computational capability of GPUs with minimum overheads, while discretizing the domain with non-uniform resolution. Different cases have been simulated in order to assess the efficiency of the BUQ grids. Theoretical and laboratory tests demonstrate that speed-ups of up to one order of magnitude can be achieved in comparison with uniform Cartesian grids. In the simulation of a hypothetical flood event induced by a levee breach in a real 83źkm long river reach, with maximum resolution of 5źm, a ratio of physical to computational time of about 12 was obtained, opening scenarios of quasi real-time 2D simulations in large domains, still retaining a high resolution where necessary. Shallow Water Equations parallel numerical scheme suitable for GPU.Novel Block-Uniform Quadtree (BUQ) grid-type, exploiting the computational capability of GPUs with non-uniform resolution.Very large domain can be simulated (38źkm river reach) with high resolution (2źm).Speed-up of one order of magnitude is achieved, in comparison with Uniform resolution Cartesian Grids.High ratio between physical and computational time which enables real-time simulations.