Efficient surface water flow simulation on static Cartesian grid with local refinement according to key topographic features.

Highlights • A new grid system is developed to detect the areas needing high-resolution mesh. • The grid system can locally refine the grid for surface water flow simulation. • The method could accelerate the model by about 3 times without accuracy loss. • The grid system is very suitable for integrating into the shallow water flow model. • The new grid system based model could be used for efficient and accurate prediction. Abstract Aiming at improving the computational efficiency without accuracy losses for surface water flow simulation, this paper presents a structured but non-uniform grid system incorporated into a Godunov-type finite volume scheme. The proposed grid system can detect the key topographic features in the computational domain where high-resolution mesh is in need for reliably solving the shallow water equations. The mesh refinement is automatically carried out in these areas while the mesh in the rest of the domain remains coarse. The criterion determining the refinement is suggested by a dimensionless number with a fixed value of 0.2 after sensitivity analysis. Three laboratory and field-scale test cases are employed to demonstrate the performance of the model for flow simulations on the new non-uniform grids. In all of the tests, the grid system is shown to successfully generate high-resolution mesh only in those areas with abruptly changing topographic features that dominate the flooding processes. To produce numerical solutions of similar accuracy, the non-uniform grid based model is able to accelerate by about two times comparing with the fine uniform grid based counterpart. [ABSTRACT FROM AUTHOR]