Computational modeling of moving boundaries in a 3D surface water model

This paper presents the computational methods for moving boundary problems in the surface water and overland flow problems. In the surface water domain, the moving boundary is modeled using a moving grid method. The mathematical formulation of the governing equations in the Arbitrary-Lagrangian-Eulerian (ALE) form and the numerical methods including different grid moving algorithms an introduced. In the overland domain, the moving boundary is simulated with a fixed grid method. The governing equations for overland flow are simplified to a diffusive wave equation. A special algorithm is employed to handle the wetting-drying process of the floodplain. A new approach that combines the moving and fixed grid method is reported in this paper, in which a typical surface water body in the river and estuary is divided into the main river channel and the submerged floodplain and modeled a two different domains with interaction through the interface.