封冻河道冰下流速分布规律研究

Study on Velocity Distribution Under Ice Cover

河渠中冰盖的存在显著改变断面的水流结构,采用k-ε紊流模型建立冰盖下水流垂向二维数值模型,并将其应用于封冻河道冰盖下流速分布的计算,探讨影响封冻河道断面流速分布规律的主要因素。结果表明:封冻河道的断面流速分布情况主要与床面糙率、冰盖糙率及河道的水流条件等影响因素相关,水流条件相同时,冰盖糙率和床面糙率的比值越小,最大流速点的位置越靠近相对光滑的一侧,且在流动的核心区流速分布并不遵循对数分布规律,在最大流速处流速梯度几乎为零。

The ice-cover in a river will obviously change the flow structure.This paper established the vertical 2-D numerical model withk-εturbulence model for ice-covered flow,simulated the velocity distribution in a freeze-up river and analyzed the main factors influencing the velocity distribution patterns.The calculated result shows that the velocity distribution in a freeze-up river mainly related to bed roughnessnb,ice roughnessniand flow conditions,under the same flow conditions,theni/nbis smaller and theUmaxis closer to the ice-cover.In the flow core the distribution of velocity deviates from the logarithmic law and the velocity gradient ofUmaxis almost zero.