Finite element-boundary integral element model for porous and highly fractured media flow

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منو

" Finite element-boundary integral element model for porous and highly fractured media flow "
W. K. Zubari T. Chamberlain

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112624
Doc. No	:	TLpq303837793
Main Entry	:	T. Chamberlain
	:	W. K. Zubari
Title & Author	:	Finite element-boundary integral element model for porous and highly fractured media flow\ W. K. ZubariT. Chamberlain
College	:	Colorado State University
Date	:	1990
student score	:	1990
Degree	:	Ph.D.
Page No	:	171
Abstract	:	A Finite Element-Boundary Element model, FMBMFRC, is developed to simulate a highly fractured local domain and a surrounding homogeneous porous regional domain. The fractured local domain is discretized by the FEM and the fractured flow condition is simulated using the Double-Porosity approach. The surrounding domain is discretized by the BIEM. In addition, a mixed boundary condition was developed to simulate general head boundary (GHB) conditions and drains in the FEM domain. Verification tests of the Double-Porosity model against the Strelstova-Adams (1978) analytical solution indicated good agreement in simulating the potentiometric surface in both fractures and porous matrix blocks. Verification tests of the GHB condition against the Theis (1935) analytical solution indicated the option can be used to extend the numerical solution of a given FEM grid to simulate semi-infinite aquifer conditions accurately. The FEM-BIEM model verification tests against FEM models indicated a maximum error of 4.9% of the total drawdown in the BIEM region, occurring under transient highly non-linear flow conditions. Under flow conditions involving lesser non-linearities, the maximum error was 2.6%. At steady conditions, the FEM-BIEM and FEM models give the same solution. The error is attributed to the steady state formulation of the BIEM domain, where the aquifer storage does not contribute to the numerical simulation. Tests of the model illustrated high computational efficiency, in comparison to CSUGWFLOW model (Warner, 1987). Savings of about 63% and 23% are realized for computer runtime and computer storage requirements, respectively. The developed model was applied to the regional Dammam Aquifer System at Bahrain and Eastern Saudi Arabia for steady and transient conditions to demonstrate its applicability. The FEM detailed discretization was assigned to the fractured aquifer parts located around the Bahrain anticline, and occupied 15% of the total 9,000 km2 modeled area. The BIEM was designed to encompass the rest of the modeled area which exhibits homogeneous hydraulic properties, and to incorporate the distant boundary conditions for the FEM domain. The validation test results indicated the model is capable of modeling the observed Dammam aquifer hydrological system adequately and efficiently.
Subject	:	Applied sciences
	:	Bahrain
	:	Earth sciences
	:	Geology
	:	Porous media
	:	Saudi Arabia