渗流自由面数值模拟方法比较

Comparison of Numerical Approaches of Simulating Seepage Flow with Free Surface

结合最新提出的自由面适应网格法,与现行的2种固定网格法即变单元渗透系数法和初流量法进行数值模拟比较,以探讨各种方法在自由面渗流计算中的优缺点及其应用情况。试探性地选取3种固定网格方法进行系统的比较,即在精度、迭代步数、网格敏感度、初设自由面敏感性上进行多方位比较,分析各方法的灵活性、鲁棒性、数值稳定性、计算效率和可靠性。结果表明,在同一网格系统下,自由面适应网格法较其它2种方法具有计算速度快、精度较高等优点,其迭代步数和结果精度对初设自由面和网格密度敏感度均较其它2种方法低。

The fixed grid methods can be classified into initial flow method,variable seepage coefficient method,variational inequality method,node imaginary flow method,imaginary elements method and the water free surface adaptive grid method which was put forward recently.Each method has its advantages and disadvantages.To ultimately guide us to choose proper methods when processing the practical seepage problems in large scale,it is of great value to evaluate their applicability including flexibility,robustness,numerical stability,computational efficiency and reliability by comparing the accuracy,iterative steps,grid sensitivity,and initial free surface sensitivity of three different fixed grid methods.The results show that the water free surface adaptive grid method is of higher computing efficiency and accuracy than the other two methods in the same grid system.The initiative steps are less,and the accuracy of computing results is less sensitive to the initial free surface and grid density than the other two methods.