ESTIMATION OF INUNDATION FLOW USING 2D-3D NUMERICAL COUPLING MODEL

Abstract

In this study, analysis of inundation flow considering overflow from a river channel due to heavy rainfall is carried out for establishment of countermeasures against flood disasters. The numerical simulations and the laboratory experiments are conducted for estimation of these phenomena. Especially, a numerical model for simulation of inundation flow considering overflow from a river channel is proposed and evaluated. The numerical model proposed in this study includes 2D horizontal model and 3D RANS (Reynolds Averaged Navier-Stokes) model. Two models are coupled by simultaneous grid method and all hydraulic quantities are connected in overlapped position of meshes. And, the standard k-e model for turbulence closure and the VOF (Volume of Fluid) method for free-surface modeling are also included in the numerical model. The proposed 2D-3D numerical coupling model is applied to a domain with a river channel and a floodplain, and the laboratory experiments are also conducted to compare with the numerical results. The numerical results have good agreements with those of experiments for the variations of the inundation flow into a floodplain considering overflow from a river channel and the effects of water level rise by river structures. It is judged that the proposed model can be helpful to establish countermeasures against inundation disasters.