论文部分内容阅读
沿海岸分布的承压含水屡中成—淡移动界面的近似解析解,是通过解一个非线性一阶偏微分方程获得的。假定接近界面的水流量随时间从一恒定值不连续地变为另一恒定值,则近似解析值与由t=0和t=∞的Dupuit 近似法所得到的稳定流精确解相吻合。近似解析解与数值解相比较表明:在各时间介值的界面前缘位置上出现约百分之十的最大误差。并且这种近似解获得的界面前缘推进和后退速度的估算值均趋于偏高。近似解非常简便,与数解值相比,更易于运算。除此之外,与数值解对比还表明,仅当在距界面前缘不太远的部位接近水流速度的突变时,无疑可以把解析近似法应用于非承压水流。这是因为自由水面的储存效应在实际到达界面前缘所能影响的下游之前,这种效应减缓了水流速度的变化。
The approximate analytic solution of confined aquifer intermediate-paleo-migratory interface distributed along the coast is obtained by solving a nonlinear first-order partial differential equation. Assuming that the water flow near the interface changes discontinuously from constant to constant over time, the approximate analytical value agrees well with the exact solution of the steady-state flow obtained from Dupuit approximation with t = 0 and t = ∞. The approximate analytic solution is compared with the numerical solution to show that about 10% of the maximum error occurs at the interface leading edge position of each time value. And the estimates of interface advance and back velocity obtained by this approximate solution tend to be high. The approximate solution is very simple and easier to compute than the number solution. In addition, comparison with numerical solutions also shows that analytical approximation can undoubtedly be applied to non-pressured water flows only when approaching a sudden change in water flow velocity at a location not too far from the leading edge of the interface. This is because the free-surface storage effect slows the change in water velocity before it actually reaches the downstream reach of the interface front.