梯形断面明渠中纵向离散系数研究

Study on longitudinal dispersion coefficient in open channel trapezoidal cross-section

基于最大信息熵原理,提出了一种确定梯形断面纵向流速分布的方法,研究了梯形断面明渠中流动横向不均匀和垂向不均匀对纵向离散的影响,建立了一个针对梯形断面明渠流动的纵向离散系数计算公式。公式将纵向离散系数与反映断面流速分布不均匀和壁面影响的参数建立联系,机理更加清楚,预测结果与其他学者相应的实验结果吻合良好,该方法理论推导过程严密,不依赖于特定的试验结果或实际测量资料,为梯形断面明渠的污染物混合输移过程中参数确定提供了有效的方法和途径。

Based on the maximum entropy principle, a velocity formula is derived to describe the variation of longitudinal velocity in both the vertical and transverse directions in a open channel with trapezoidal cross-section. The effect on the longitudinal dispersion coefficient of the inhomogeneity in the vertical and transverse directions of the flow is studied. And the conclusions fairly agree with the work of other researchers. A formula for predicting the longitudinal dispersion coefficient in a open channels with trapezoidal cross-section is proposed. According to the formula, the longitudinal dispersion coefficient is determined by two parameters which reflect the inhomogeneity of the velocity distribution and the influence of channel walls. The method on the longitudinal dispersion in this paper is not based on some special experimental results or the field data. Because of the solid theoretical basis, this method can be used as an efficient tool to determine the longitudinal dispersion coefficient in any open channels with trapezoidal cross-section.