二维浅水方程运行流场，采用有限元法变成，采用不规则三角形网格的分步杂交方法，在前半步长用特征线法，后半步长用集中质量有限元方法求解方程，是变边界模型-Two-dimensional shallow water equations to run the flow field into a finite element method, using irregular triangle mesh step-by-step hybrid methods, with the former half-len