Propagation of the effect of upstream bend circulations to downstream flow and sediment transport in consecutive river bends

• RC leads to the increases of τ ∼ b and SS * near the inner bank in the downstream bend. • The increase rates of τ ∼ b and SS * show positive relationships with the RC strength. • RC slows the shift of the high-value zones of τ ∼ b and SS * to the outer bank. • The above effects of RC on τ ∼ b are more pronounced at lower water depths. Despite their critical role in shaping meandering rivers, the hydraulics, sediment transport, and the interplay of consecutive bends remain inadequately understood, hindering our full comprehension of fluvial processes and river evolution. A numerical approach, employing the RNG k - ε model, is used to investigate the flow and sediment transport in a downstream bend (135°) affected by residual circulations (RC) from an upstream reverse bend (90°). Results reveal the mechanism of RC altering the flow and sediment transport in the downstream bend. Compared with a single bend, RC results in a shift of the high streamwise velocity zone to the inner bank in the downstream bend. The presence of a connected upstream bend substantially increases the maximum values of bed shear stress, sediment transport capacity, and the Darcy–Weisbach friction coefficient in the downstream bend. Besides, the rate of increase shows a positive relationship with the strength of RC, which decreases as the transition length increases. Moreover, the locations of the maximum bed shear stress and the maximum sediment transport capacity at the cross-section are closer to the inner bank (up to 0.25 B ). Further analysis of the influence of water depth reveals that the above effects of RC on bed shear stress are more pronounced at lower water depths. These effects of RC can promote the occurrence of shore cutting and the formation of outer bank benches in the downstream bend. The findings of this study will contribute to a better understanding of sediment transport and channel evolution in consecutive bends, and provide valuable insights for meandering river management.