基于适体坐标变换的二维河冰模型

为精确模拟流动边界条件,克服边界形状复杂、长宽尺度相差悬殊及由于水位变化引起计算边界变化等困难,针对天然河道边界弯曲复杂等特点,应用水动力学和热力学等原理,建立了适体坐标下的二维河冰数值模型,模型主要包括流速场,水温沿河道变化,水内冰浓度分布,面冰输移,冰盖推进、稳定和消融,冰盖下冰的输移、堆积和冲蚀等,考虑了冰盖底部水中冰堆积和冰盖前沿形状对封冻过程的影响。采用MacCormack步进格式计算方法,并应用黄河河曲段实测资料对数值模拟结果进行了验证。验证结果表明,提出的数值模型能较好地体现河道的封冻过程。

2D numerical model for river-ice processes based upon body-fitted coordinate

To simulate accurately the complicated boundary conditions and overcome the problems caused by wide gap of scale between length and width,and change of computational boundary conditions as water-level variations,a 2D river-ice numerical model based upon the body-fitted method is developed by using the principles of hydrodynamics and thermodynamics and considering the influence of the frazil ice accumulating under ice cover and the shape of freezing fringe of ice cover during the river-ice process. The model is capable of determining the velocity field,the distribution of water temperature,the concentration distribution of the frazil ice,transportation of the floating ice,the progression,stability and thaw of ice cover and the transportation,accumulation and erosion of ice under ice cover MacCormack scheme is used to solve the equations.The model is validated through the field observations in Hequ reach of the Yellow river. The results show that the 2D numerical model presented is capable of simulating the river-ice process with accuracy.