明渠挟沙水流的两相流模式

Modeling sediment-laden flow in open channels by two-phase flow theory

本文从两相流基本方程出发对明渠挟沙水流含沙量、流速垂线分布及近底层平均流动特性进行了理论研究，建立了一个新的泥沙扩散方程，并用大量资料进行了验证．结果表明：现有含沙量公式和流速垂线分布公式只是本文理论模式在低含沙量条件下的简化形式。当含沙量增加时，固相泥沙对流动结构的影响亦趋显著而不可忽略．精确模拟水沙流动，需要发展高级的两相湍流模式．

Based upon the fundamental equations for fluid-solid two-phase flows, this paper investigates theoretically the sediment-laden flows in open channels for velocity and sediment concentration profiles. A new equation for sediment distribution is established from a sound analysis of the mixture's vertical velocity. The developed model is extensively tested against the comprehensive measurements of Coleman (1986), Vanoni and Nomicos (1959) as well as Einstein and Chien (1955) for heavy sediment concentration flows. The results show that the formulas, established by previous researchers, for velocity and sediment concentration are simply the special cases of the present model for low sediment concentration flows. As sediment concentration increases, the influences of sediment particles on flow structure become progressively significant and cannot be neglected. Advanced turbulence models are needed for more refined modeling.