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A BEM solution of steady-state flow problems in discrete fracture networks with minimization of core storage
No full textA BEM code for ground water problems in multizoned domains with normal boundary flux discontinuities
No full textA BEM Code for Ground‐Water Problems in Multizoned Domains with Normal Boundary Flux Discontinuities
No full textA numerical code which utilizes the boundary element method (BEM) for solving steady-state ground-water flow problem is illustrated. The paper concentrates on accuracy in studying situations which are generally considerd to involve some mathematical difficulty, such as zoned domains and flux discontinuities. A numerical BEM code is proposed, the main features of which involves accurately calculating flux discontinuities using a structure particularly flexible in multizoned domains. Two examples are reported, the results of which are comparable with those available in the literature
A BEM solution of steady-state flow problems in discrete fracture networks with minimization of core storage
No full textA boundary element method (BEM) solution for the problem of the fluid flow in a three-dimensional discrete fracture
network (DFN) is proposed. A DFN is an assembling of polygons which resemble the fractures in a rock mass. The
position, extension, orientation and transmissivity of each fracture of the network are excluded by specific statistical
distributions. For a single problem, a significant number of DFNs has to be generated and the fluid flow has to be
assessed in each of them in the context of a Monte-Carlo procedure. Even for relatively small domains, a DFN may
include a large number of fractures. As a consequence, in order to solve the whole problem with standard finite-element
method (FEM) codes, a big amount of core memory and large input data files are required. The main advantage of the
proposed solution is mainly the minimization of the core memory. This is attained by handling the flow quantities in
such a way the equation system of the overall network is never assembled. Only a relation per each fracture among
nodal fluxes and heads of the traces (i.e., intersections among fractures) is defined and stored in a random access file.
This relation is obtained by means of the application of the BEM to each single fracture of the network. Both constant
and quadratic element representations are used in order to define the relevant nodal quantities. The use of constant
elements allows to avoid the direct treatment of the points of flux discontinuity. No special care is applied to the
discretization of the boundary of each fracture. The overall problem is solved by means of an iterative procedure, by
retrieving the necessary coefficients from the random access file. The results are in acceptable agreement with the ones
provided by a commercial FEM code. We remark that saving core memory without special care in the discretization of
the DFN makes the solution competitive, especially when dealing with networks with a high number of fractures
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