天然河道丁坝群局部冲刷三维数值模拟

Three-dimensional numerical simulation of local scour based on spur dikes in a natural river

为研究天然河道中丁坝长度对河床的冲刷影响,基于天然河道形状和实际丁坝群布置,提出适用于天然河道形状的丁坝群局部冲刷计算流体力学(CFD)三维数值模拟方法,建立了滦河马良子段丁坝群三维模型。采用RNG k-ε模型模拟计算,用VOF方法进行自由表面的追踪,并对丁坝局部冲刷坑形态及冲刷深度进行了数值模拟。对比实测数据,数值模拟结果与实测结果非常吻合。针对丁坝群中局部冲刷最严重的丁坝,对其长度进行调整,调整后冲坑深度明显改善。

In order to study the influences of the spur dike length on the local scour of riverbed in the natural rivers,based on the shape of the natural river channels and the actual layout of the spur dikes,a three-dimensional computational fluid dynamics(CFD)numerical simulation method for the local scour of the spur dike group suitable for the shape of the natural river channel is proposed,and a three-dimensional model for the spur dike group located at the Maliangzi section of the Luanhe River in Hebei Province is established.The shape and erosion depth of the scouring pit in the groin head are numerically simulated by using RNG k-εmodel and VOF method which can track the free surface.The shape and scouring depth of the scouring sump are numerically simulated.The numerical simulation results are in good agreement with the measured values,and the reliability of the numerical model is verified.The maximum scouring pit depth and scope of the spur dikes are obviously reduced after adjustment.