Three‐Dimensional Computation of Flow and Bed Deformation

A three‐dimensional (3D) flow model is developed to improve the defects of a two‐dimensional (2D) model proposed by Shimizu and Itakura. Calculated results are compared with experiments as well as with results calculated by the 2D model. The flow field is predicted more correctly by the 3D model than the 2D model. A simplification of the full 3D model is made, in which the depth‐wise profile of the velocity is assumed to be logarithmic. This approach is favorably tested in the calculation of flow in a meandering bend. The simplified 3D model is applied to the computation of bed deformation by bed load as well as suspended load transport in meandering channels. Good agreements are found in comparison with the experimental results. A definite difference between the 3D and 2D models is found in the predicted bed deformation with suspended load. Evaluations of the flow and bed deformation by the proposed model are clearly demonstrated through application examples, and the validity of the new calculation model is verified.