Abstract
The engineering applications of two-dimensional (2D) hydrodynamic models are restricted by the enormous number of meshes needed and the overheads of simulation time. The aim of this study is to improve computational efficiency and optimize the balance between the quantity of grids used in and the simulation accuracy of 2D hydrodynamic models. Local mesh refinement and a local time stepping (LTS) strategy were used to address this aim. The implementation of the LTS algorithm on a 2D shallow-water dynamic model was investigated using the finite volume method on unstructured meshes. The model performance was evaluated using three canonical test cases, which discussed the influential factors and the adaptive conditions of the algorithm. The results of the numerical tests show that the LTS method improved the computational efficiency and fulfilled mass conservation and solution accuracy constraints. Speedup ratios of between 1.3 and 2.1 were obtained. The LTS scheme was used for navigable flow simulation of the river reach between the Three Gorges and Gezhouba Dams. This showed that the LTS scheme is effective for real complex applications and long simulations and can meet the required accuracy. An analysis of the influence of the mesh refinement on the speedup was conducted. Coarse and refined mesh proportions and mesh scales observably affected the acceleration effect of the LTS algorithm. Smaller proportions of refined mesh resulted in higher speedup ratios. Acceleration was the most obvious when mesh scale differences were large. These results provide technical guidelines for reducing computational time for 2D hydrodynamic models on non-uniform unstructured grids.
Highlights
The numerical simulation of shallow water flow is frequently used in flood forecasting, river regulation, and flood-control planning [1]
This showed that the local time stepping (LTS) scheme is effective for real complex applications and long simulations and can meet the required accuracy
Acceleration was the most obvious when mesh scale differences were large. These results provide technical guidelines for reducing computational time for 2D hydrodynamic models on non-uniform unstructured grids
Summary
The numerical simulation of shallow water flow is frequently used in flood forecasting, river regulation, and flood-control planning [1]. Given the need for better accuracy and breadth of shallow-water simulations in engineering applications, a balance between the number of cells, simulation accuracy, and computational time needs to be found. Addressing this issue using optimization of the solving algorithm [2,3,4] has received much research attention, as has the use of computer hardware acceleration and parallel computing technology [5,6,7]. The local mesh refinement technique is especially efficient for balancing the number of grids and the accuracy of the simulation. The simulation accuracy can be ensured with only a small increase
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