Flood discharge from the dam surface and tailwater discharge from the power station directly affect the hydrodynamic processes in the downstream river channel as well as at the entrance area of approaching channel, which are closely related to the navigation stability and safety of vessels entering or leaving the ship lock. To investigate the influence of different dam flood discharge operational scenarios on the hydrodynamic characteristics at the entrance of the downstream ship lock approach channel, a three-dimensional nested coupled CFD model is established for free surface flows with strong nonlinearity in the stilling basin and unsteady turbulent flows in the downstream channel of the Xiangjiaba Hydraulic Project. The model adopts the Reynolds-Averaged Navier–Stokes (RANS) equations for unsteady flows, combined with the Realizable k-ε turbulence model as well as the VOF free surface tracking method for stilling basin flow and the standard k-ε turbulence model for downstream river flow, respectively. Numerical investigations are conducted to clarify characteristics of river flows associated with the discharged flood from dam surface and tailwater from power stations under different flood discharge patterns. The results show that the balanced discharge scenario involving the combined operation of releasing the flood through the crest and middle outlets of both left and right stilling basins can significantly reduce flow velocity and water level fluctuations near the entrance of the approach channel. Optimizing flood discharge scheduling can effectively improve flow conditions at the entrance area, which is beneficial to enhancing navigation safety for ships.
Zhang et al. (Sat,) studied this question.