A combined finite and infinite element approach for modeling spherically symmetric transient subsurface flow

This paper presents a finite element-infinite element coupling approach for modeling a spherically symmetric transient flow problem in a porous medium of infinite extent. A finite element model is used to examine the flow potential distribution in a truncated bounded region close to the spherical cavity. In order to give an appropriate artificial boundary condition at the truncated boundary, a transient infinite element, that is developed to describe transient flow in the exterior unbounded domain, is coupled with the finite element model. The coupling procedure of the finite and infinite elements at their interface is described by means of the boundary integro-differential equation rather than through a matrix approach. Consequently, a Neumann boundary condition can be applied at the truncated boundary to ensure the C-continuity of the solution at the truncated boundary. Numerical analyses indicate that the proposed finite elementinfinite element coupling approach can generate a correct artificial truncated boundary condition to the finite element model for the unbounded flow transport problem. Crown Copyright & 2008 Published by Elsevier Ltd. All rights reserved.