簡易Lagrange型解法を用いた掃流砂モデルによる富田川河床変動シミュレーション

Abstract

This paper presents numerical simulation of riverbed variation using two-dimensional depth-averaged flow model with a simplified Lagrangian bedload model and its application to actual river. The scheme of Lagrangian-type bedload model resembles the actual phenomenon of sediment movement in comparison with the model of Euler type and it is useful when the change of sediment movement direction is extreme on a small scale. The Lagrangian-type model can simulate a change in the direction of moving sediment considering the local flow and bed slope along the moving paths regardless the computational grid structure. However, the heavy computation load is a significant bottleneck for a simulation in many cases. In this study, we introduced the simplified Lagrangian bedload model to a two-dimensional depth-averaged flow model and applied the model to an actual river.