Coupling of 1-D and 2-D Hydrodynamic Models Using an Immersed-Boundary Method

Numerical simulations of flooding events through rivers and channels require coupling between 1-D and 2-D hydrodynamic models. The rivers and channels are relatively narrow and the widths are smaller than the grid resolution of the 2-D model. The shapes of the rivers and channels are complex and do not necessarily coincide with the grid points. The coupling between the 1-D and 2-D models are challenging. In this paper, a novel Immersed-Boundary (IB) type coupling is implemented. Using this method, no linkpoint needs to be manually determined, nor does the discharge boundary conditions need to be specified on the linkpoints. The linkpoints will be dynamically determined by comparing the water levels in the 1-D channel and the surrounding dry cell elevations in the 2-D model. The linkpoint flow conditions thus can be dynamically calculated by the IB type of implementation. This coupling method enables more realistic simulations of water exchange between channels and dry lands during a flooding event comparing to the traditional coupling method.