挟沙水流速度与含沙量垂向分布关系探讨

采用数据拟合构造的挟沙水流掺混长度,结合Prandtl掺混长度理论,得到新的挟沙水流流速分布。类比动量传递系数表达式与掺混长度的关系,结合挟沙水流流速分布公式,得到新的含沙量垂线分布公式。分别利用水槽及河道实测资料验证,结果表明流速公式与含沙量公式可以客观准确地描述流速、含沙量垂向变化规律,对含沙量有更高的精度。误差分析表明:近底层流速误差较大,说明底部边界层的选取与判别仍需深入探究;近表层含沙量误差较大,说明含沙量参考点的选取在理论上仍需研究,以摆脱其随机影响。

Relationship between vertical distributions of velocity and sediment concentration of sediment-laden flow

Using the mixing length of sediment-laden flow constructed with data fitting and combining the Prandtl mixing length theory, a new equation describing the velocity distribution of sediment-laden flow was established. Based on this new equation and the analogy of the relationship between the momentum transfer coefficient and mixing length, a new equation describing the vertical distribution of sediment concentration was also established. Through verification with observed data from the flume experiment and field survey, it was found that these two equations can objectively describe the vertical variations of velocity and sediment concentration, showing a higher precision in describing the sediment concentration. The error analysis shows that the error of the near-bottom velocity is large, indicating that the selection and judgment of the bottom boundary layer need further investigation; the error of the sediment concentration close to the surface is large, indicating that the selection of the reference point for the sediment concentration requires further theoretical research, in order to discard the influence of random effects.