The natural rivers are meandering.The channel width changes due to variations in runoff,which have an important impact on shipping safety and the implementation of waterway improvement projects.A study on the changes in the hydrodynamic characteristics of curved channels under different channel widths and channel curvatures has been conducted.The RNG k-ε turbulence model is adopted,and the free liquid surface is captured by the volume function method (VOF).Numerical simulation studies are carried out for three channel widths and four channel curvatures.The results show that with the increase of channel width,flow separation in the bend becomes more significant.The longitudinal velocity at the bend apex section rises as channel width increases.Both the scale and intensity of the secondary flow increase with channel width,with the maximum value appearing at the S60 section.As the channel curvature increases,the superelevation of water surface at the curved crown becomes increasingly prominent.The scale of outer-bank circulation (OBC) enlarges,and its position shifts forward with the rise of channel curvature.The research results can provide scientific basis and reference for waterway management and regulation engineering.