象山港水交换数值研究──Ⅰ.对流-扩散型的水交换模式

以溶解态的保守性物质作为湾内水的示踪剂，建立了对流－扩散型的海湾水交换数值模型。数值模型使用参数化的方法把重力环流和潮振荡的垂向剪切作用的水平混合效应包纳在水平二维的示踪剂对流－扩散方程中。在空间网距较小时，模型的稳定性和守恒性均可满足海湾水交换研究的需要。

NUMERICAL STUDY OF THE WATER EXCHANGE IN THE XIANGSHANGANG BAY I. ADVECTION-EIFFUSION WATER EXCHANGE MODEL

Using a dissolved conservative marerial as a tracer in the warer, a vertically integrated 2-D advection-diffusion water exchange numerical model was developed for the water exchange study in Xiangshangang Bny. The model consists of a hydrodyamic model and an advection-diffusion tracer model. The governing equation of the tracer model is formed by integrating the 3-dimensional traCer mass conservation equation. The effects of the gravity residual circulation and vertical hdal current shear on the water cxchange are parameterized with the dispersion coefficients as fellows.where, u, is the velocihes, c is the traCer concentration, kir and kis are the horizontal dispersion coefficients caused by the gravity residual circulation and the vertical shear effect of the tidal current oscillation in the tidal period respectively; kit, is the venically integrated tundent coefficient. In the numerical model, the theer flux normal to the solid boundary is set to zero. The beer concentration is also set to be zero on the open boundary when there is inflow. providing the initial tracer concentration is c(to) in the bay, the water exchange rate R(x,y,t) can be calculated in terms of the tracer concentration c(xy,t) as follow:The TRIM model is accepted as the hydrodynamic model and its numerical scheme is appied in the numerical tracer model. Generaly, the stability and the conservation of traCer mass of the numerical model can sahsfy the reqinrement of the water exchange study in the estuare and the embaymenL Because the water exchange model is 2-dimensional, a lot of time is saved in calculation. As the main vertical mixing mechanisms are included, the model simulates well the water exchange process.