Numerical simulation of water flow characteristics in curved channels and ship motion characteristics

In order to reveal the influence of the geometric parameters of the curved channel on the navigable water flow conditions and ship motion characteristics, the typical curved channel section of the Yangtze-to-Huaihe River Water Diversion Project was taken as the research object. Moreover, the mathematical model of the water flow based on MIKE21 and the MMG ship manoeuvring model were established. The influence of the turning angle (θ = 60°, 90°, 120°), the bending radius (R = 540, 1000, 1500 m), and the channel width (B = 60, 90 m) on the flow characteristics of the curved channel were analyzed in a systematic way, and the movement law of 1000 t class cargo ship in the curved channel was quantified. The results show that the increase in the turning angle significantly aggravates the complexity of water flow; the backwater at the top of the bend at θ = 120° rises by 0.012 m compared with that at 60°, and the maximum transverse gradient of the water surface shifts from the downstream 1/3 to the upstream 1/3; the main stream shifts to the convex bank. The increase of the bending radius improves the navigable conditions, and the difference in water level between the concave and convex banks at R = 1500 m decreases by 60% compared with that at R = 540 m; the maximum flow velocity decreases from 0.55 m/s to 0.35 m/s. The reduction of the channel width significantly worsens the water flow conditions, and the maximum flow velocity and the water level difference between upstream and downstream increase significantly at B = 60 m compared with B = 90 m. As for the ship motion characteristics, the downstream ship is dominated by the water flow, and the traverse speed with the rudder angle and drift angle show a strong negative correlation; the upstream ship is dominated by its own power, and the correlation of each parameter is weak.