防洪模拟中的地形自适应网格生成技术

在洪水波演进过程中，地形是主要影响因素之一，根据计算区域内地形变化自动调整网格分布，可以使计算模型和计算结果能更加细致和精确地反映客观地形地貌。本文分析了江河洪水演进模拟中网格自动生成方面的需求，探讨了洪水模拟中两类地形自适应问题：突变地形和缓变地形。对于如堤防等阻水建筑物，概括为一种地形突变，网格自动生成时此类地形的自适应可以转化为边界自适应问题，因为此类地形突变一般均能以连续折线来表示。而对于缓变地形，本文提出了通过曲面样条函数拟合，形成计算区域内连续光滑的地形曲面，从而通过各点高程梯度来控制网格尺寸，实现网格生成过程中的地形自适应，即在地势平坦区域加大网格尺寸，而在地势变化剧烈的区域，加密网格。

Auto-generation technique of computational grid adapted to terrain variation in simulation of flooding

The technique of auto-generating computational grid adapted to terrain variation in simulation of flooding is developed. Two kinds of terrain adaptation problems corresponding to the abrupt change of elevation, such as levee or embankment, and gradually topographic variation are considered. With regard to the first, the auto-generation of the grid is transformed into the auto-adaptation of the boundary, so that the variation of elevation can be expressed by discontinuous broken line. In case the second, the surface spline function can be applied for interpolation of elevation and the grid sige can be automatically controlled by the gradient of the variation.