杭州市四堡排污工程浓度场计算

Calculation of concentration fields of wastewater discharging for Hangzhou Sibao project

根据钱塘江四堡河段潮流变化大、水深相对较小和江心排污的特点，采用一、二维相结合的两步计算模型，先对全域进行一维非恒定流计算，在获得近区计算边界条件的基础上，对近区采用完全深度平均紊动动能－耗散率（Ｋ－ε）紊流模型进行二维计算。与传统深度平均Ｋ－ε紊流模型相比，该模型反映了流速在深度方向分布不均匀的影响；计入了自由水面与水下地形的影响；采用了组合坐标系统。经观测资料验证表明，该计算模型能较好地描述复杂流动的浓度分布。

A two step mathematical model is developed for the vertical jet discharging into tidal flows in this paper, taking account of the characteristic of Sibao segment of Qiantang River. This model connects the computation of 1 D and 2 D flows. First, computation of 1 D is carried out to get the boundary conditions of the near field. Then, the complete depth averaged K ε turbulence model is used for computation of 2 D flow in the near field. The calculated results agree well with those of observation. It has shown that this model is able to simulate the concentration distribution of complex flows.