Some drawbacks affecting the variable mesh finite element solution of unconfined flow problems are discussed and a procedure is suggested aimed at avoiding them in steady state and transient analyses. In particular, it is shown that the results of standard algorithms often used in practice may present spurious oscillations of the phreatic surface in the vicinity of the intersection with a pervious boundary exposed to the atmosphere. They may become exceedingly large when a limited number of elements is adopted in the mesh, and in some cases lead to non correct final (steady state) configurations of the free surface. In order to eliminate this negative effect from the finite element analysis, a simple criterion is suggested based on an algorithm for non linear function minimization. Some applications of this technique are presented to two- and three-dimensional unconfined problems.

On the variable mesh finite element analysis of unconfined seepage problems

CIVIDINI, ANNAMARIA;GIODA, GIANCARLO
1989-01-01

Abstract

Some drawbacks affecting the variable mesh finite element solution of unconfined flow problems are discussed and a procedure is suggested aimed at avoiding them in steady state and transient analyses. In particular, it is shown that the results of standard algorithms often used in practice may present spurious oscillations of the phreatic surface in the vicinity of the intersection with a pervious boundary exposed to the atmosphere. They may become exceedingly large when a limited number of elements is adopted in the mesh, and in some cases lead to non correct final (steady state) configurations of the free surface. In order to eliminate this negative effect from the finite element analysis, a simple criterion is suggested based on an algorithm for non linear function minimization. Some applications of this technique are presented to two- and three-dimensional unconfined problems.
1989
Finite elements; unconfined flow; seepage
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/559674
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