2015 Volume 3 Issue 1 Pages 174-183
A multilevel grid-type turbulent shallow flow model combined with an equilibrium sediment transport model (KMR-MB: Kinematic Mesh Reconstruction for Movable Bed) is proposed. The KMR method is a kind of multilevel grid model with dynamic refinement that combines grid cells to efficiently capture the unsteady flow phenomena. Saito et al. (2012)1),2) have applied the KMR approach to open channel flows around a bridge pier and have shown the advantage of the model. They used the maximum value of the strain and rotation parameters for the threshold for quadtree and 3×3 grid divisions. We have extended the model for computations of morphological phenomena in rivers by incorporating an equilibrium sediment transport model as well as a bed continuity equation, and used new criteria for grid cell refinement. We used an average curvature of the bed surface as the criteria for refinement and combined quadtree-type grid cells. The present model has been applied to simulate the alternate bar formations. The experimental result by Akahori et al. (2011)3) was used to validate the model. The comparison between numerical and experimental results showed that the present KMR-MB can excellently simulate the phenomena with less CPU time than those computed with the fixed grid.