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为分析弯曲河道中螺旋流对中性物质纵向和横向混合作用,建立了一种物质输运混合的三维数学模型。该模型在平面上采用正交曲线,在垂直面上采用σ坐标系统来拟合边界。采用标准的k-ε模型来计算水流的紊动粘性系数。模型计算值和实测值吻合较好。在其他条件不变的前提下,将计算的二次环流强度分别增强到2倍和减弱到1/6倍后,计算出中性物质浓度场分布。结果表明:弯曲河道主二次环流的改变对污染物的空间分布影响较大。因此,在弯曲河道(尤其对急弯道)中的主二次环流的侧向混合作用不应被忽略。
In order to analyze the effect of spiral flow on the longitudinal and lateral mixing of neutral materials in curved river, a three-dimensional mathematical model of mixed material transport was established. The model uses an orthogonal curve in the plane and the σ coordinate system on the vertical plane to fit the boundary. The standard k-ε model is used to calculate the turbulent viscosity coefficient of the water flow. The calculated values agree well with the measured values. Under the same conditions, the distribution of neutral concentration field was calculated after the calculated secondary circulation intensities were increased to 2 times and to 1/6 times respectively. The results show that the change of the main circulation in the curved channel has a great influence on the spatial distribution of pollutants. Therefore, the lateral mixing of the main secondary circulation in a curved channel (especially for a sharp curve) should not be neglected.