黄河大柳树—沙坡头河段典型弯道水流运动平面二维数值模拟

Two-dimensional numerical simulation of flow motion in typical bends of Daliushu-Shapotou Reach of Yellow River

建立了适体坐标系下的平面二维紊流水流数学模型,对黄河在宁夏回族自治区中卫市境内的大柳树—沙坡头河段典型弯道的水流运动进行数值模拟。为了反映弯道环流的影响,对动量方程进行修正,紊流模型采用修正的RNGk-ε模型。通过对黄河大柳树—沙坡头河段连续弯道水流运动数值计算结果与实测结果的对比分析,表明该模型能够准确地模拟具有复杂地形的天然河流弯道中的水流运动。利用所建立的模型计算了4种典型工况下水面的纵比降和横比降,得到一些有益的结论。

A two-dimensional turbulent model in body-fitted coordinates was established to simulate the flow motion in some typical bends of Daliushu-Shapotou Reach of Yellow River in Zhongwei City of Ningxia Hui Autonomous Region.In order to reflect the circulation currents in the bends,the momentum equations in the model were improved by adding an additional term,and a modified RNG k-ε model was adopted for the turbulent flows.The numerical results and the measured data for the flow motion in the consecutive bends of Daliushu-Shapotou Reach were compared and analyzed.The results indicate that the proposed model can accurately simulate the flow motion in bends of natural rivers with complicated topography.Some useful conclusions are drawn based on the longitudinal slopes and transverse gradients of water surface in four typical cases calculated by means of the present model.