丁坝群对弯道水力特性影响的数值模拟研究

Numerical simulation of the influence of spur dikes on the hydraulic characteristics of a bend channel

弯道螺旋流是弯道水流的特点之一,弯道环流会造成凸岸发生淤积,凹岸遭受冲刷,对护岸工程非常不利。在弯道中布设丁坝可有效减弱弯道螺旋流强度,改善水流流态,保护岸坡稳定。采用RNGk-ε湍流模型,应用VOF法捕捉自由水面,采用半隐式SIMPLE算法求解速度与压力耦合方程组,模拟在60°弯道内布设丁坝群后弯道水流特性。研究表明:数值模拟的水位、流速和试验数值据吻合良好。弯道内设置丁坝群后,可有效改善凹岸区域的冲刷及凸岸的淤积,主河槽的水深增加,水面横比降减小,说明丁坝群的布置在稳定弯道水流,防止岸坡冲於方面有较好的效果。

The spiral flow in bends can easily causes a problem of river erosion at concave banks and sediment deposition at convex banks in actual bend rivers, and is unfavorable for bank protection engineering. The spur-dikes can effectively control the spiral flow and improve the flow patterns in bends. The time-averaged equations closed with the RNG k-ε turbulence model were used to simulate the flows in bends to analyze the function of spur-dikes in bends. The VOF (Volume of fluid) method was applied to track the flow free surface. The velocity and pressure coupling equations were solved by the SIMPLE algorithm. The predicted water level and velocity distributions in the bend showed a good agreement with experimental data. The spur-dikes can effectively eliminate the problem of river erosion at concave bank and sediment deposition at convex bank in the bend channel, increase the water level in the main channel, and decrease transverse slope of free surface. It can be concluded that the layout of spur dikes is effective in stabilizing the bend flow and preventing bank slope from rushing.