Automatic Generation of Seepage Flow Nets by Finite Element Method

Abstract

An analytical method for automatically generating a seepage flow net using the finite element method (FEM) is described. This technique includes a new, more analytical (as compared with numerical) approach to determining the boundary conditions for computing the stream function and a refined approach to handling the transition between multiple layers. Equipotentials are obtained by contouring the results of the FEM solution where total head at each node is computed. The boundary conditions are then modified using the Cauchy‐Riemann equations governing conjugate harmonic functions, and a second FEM problem is solved to compute stream function at each node. Appropriately contouring these results produces the desired flow lines, and the flow net is complete. Procedures for confined flow, unconfined flow, and multilayer systems are presented with examples. A discussion for axisymmetric problems is also given.