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Permeability Tensor (permeability + tensor)

Distribution by Scientific Domains
Engineering58%

Selected Abstracts

Anisotropic Variation Law of Rock Permeability with the Burial Depth of Limestone

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2003
TIAN Kaiming
Abstract, Permeability tensors of both macrofracture and microfracture systems were measured progressively along the depth of limestone formations at severed sites. It was found that the principal permeability values Kx, Ky and Kz in these permeability tensors all decrease simultaneously and logarithmically with depth. However, the limestone aquifers are composed of an upper region where the larger permeability ellipsoid is upright or prolate and characterized by KzKx and Kz>Ky, a transitional zone, and a lower zone whose smaller permeability ellipsoid is horizontal or oblate and characterized by Kzpermeability tensors in a macrofracture system displays a similar pattern with that in a microfracture system. It is next to impossible to examine the rock permeability tensor of the aquifer just by measuring the hydraulic parameters of macrofracture system directly, unless the limestone aquifer is exposed on or near the earth's surface. Therefore, the permeability tensors of a macrofracture system at any depth may be indirectly and roughly determined from the gaugeable permeability tensors of the microfracture system by conversion. This anisotropic variation law of rock permeability with depth is of great significance in the study of three-dimensional fracture water flow the huge carbonate formations and in the research on the conditions of karst development and karst distribution. [source]

Numerical estimation of REV and permeability tensor for fractured rock masses by composite element method

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 12 2008
S.-H. Chen
Abstract The Monte Carlo method is used to generate parent stochastic discrete fracture network, from which a series of fractured rock samples of different sizes and orientations are extracted. The fracture network combined with a regular grid forms composite element mesh of the fractured rock sample, in which each composite element is composed of sub-elements incised by fracture segments. The composite element method (CEM) for the seepage is implemented to obtain the nodal hydraulic potential as well as the seepage flow rates through the fractured rock samples. The application of CEM enables a large quantity of stochastic tests for the fractured rock samples because the pre-process is facilitated greatly. By changing the sizes and orientations of the samples, the analysis of the seepage characteristics is realized to evaluate the variation of the permeability components, the existence of the permeability tensor and the representative element volume. The feasibility and effectiveness are illustrated in a numerical example. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Flow,stress coupled permeability tensor for fractured rock masses

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 11 2008
Chuang B. Zhou
Abstract In this paper a new analytical model is proposed to determine the permeability tensor for fractured rock masses based on the superposition principle of liquid dissipation energy. This model relies on the geometrical characteristics of rock fractures and the corresponding fracture network, and demonstrates the coupling effect between fluid flow and stress/deformation. This model empirically considers the effect of pre-peak shear dilation and shear contraction on the hydraulic behavior of rock fractures and can be used to determine the applicability of the continuum approach to hydro-mechanical coupling analysis. Results of numerical analysis presented in this paper show that the new model can effectively describe the permeability of fractured rock masses, and can be applied to the coupling analysis of seepage and stress fields. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Convergence study of a family of flux-continuous, finite-volume schemes for the general tensor pressure equation

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9-10 2006
Mayur Pal
Abstract In this paper, a numerical convergence study of family of flux-continuous schemes is presented. The family of flux-continuous schemes is characterized in terms of quadrature parameterization, where the local position of continuity defines the quadrature point and hence the family. A convergence study is carried out for the discretization in physical space and the effect of a range of quadrature points on convergence is explored. Structured cell-centred and unstructured cell-vertex schemes are considered. Homogeneous and heterogeneous cases are tested, and convergence is established for a number of examples with discontinuous permeability tensor including a velocity field with singularity. Such cases frequently arise in subsurface flow modelling. A convergence comparison with CVFE is also presented. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Numerical modelling of anisotropy and eddy current effects in ferromagnetic laminations using a co-energy formulation

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 5 2001
L. R. Dupré
Abstract The paper deals with a numerical model for the evaluation of electromagnetic fields in one steel lamination under the influence of a rotating magnetic flux, taking into account anisotropy effects. For this purpose a detailed material model, described by a differential permeability tensor, is included in the macroscopic electromagnetic field calculations in one lamination. Here, by geometrical and physical considerations, the governing Maxwell equations are reduced to a system of parabolic PDEs for the components of the magnetic field vector, under appropriate boundary and initial conditions. We present a suitable numerical approximation based upon a finite element,finite difference method, which properly takes into account the material characteristics. The study leads to a more realistic numerical modelling of the electromagnetic phenomena inside electric and magnetic conducting laminations due to anisotropy effects. Numerical results are compared with those from simplified analytical formulae. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Anisotropic Variation Law of Rock Permeability with the Burial Depth of Limestone

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2003
TIAN Kaiming
Abstract, Permeability tensors of both macrofracture and microfracture systems were measured progressively along the depth of limestone formations at severed sites. It was found that the principal permeability values Kx, Ky and Kz in these permeability tensors all decrease simultaneously and logarithmically with depth. However, the limestone aquifers are composed of an upper region where the larger permeability ellipsoid is upright or prolate and characterized by KzKx and Kz>Ky, a transitional zone, and a lower zone whose smaller permeability ellipsoid is horizontal or oblate and characterized by Kzpermeability tensors in a macrofracture system displays a similar pattern with that in a microfracture system. It is next to impossible to examine the rock permeability tensor of the aquifer just by measuring the hydraulic parameters of macrofracture system directly, unless the limestone aquifer is exposed on or near the earth's surface. Therefore, the permeability tensors of a macrofracture system at any depth may be indirectly and roughly determined from the gaugeable permeability tensors of the microfracture system by conversion. This anisotropic variation law of rock permeability with depth is of great significance in the study of three-dimensional fracture water flow the huge carbonate formations and in the research on the conditions of karst development and karst distribution. [source]

An a posteriori error estimator for the mimetic finite difference approximation of elliptic problems

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2008
Lourenço Beirão da Veiga
Abstract We present an a posteriori error indicator for the mimetic finite difference approximation of elliptic problems in the mixed form. We show that this estimator is reliable and efficient with respect to an energy-type error comprising both flux and pressure. Its performance is investigated by numerically solving the diffusion equation on computational domains with different shapes, different permeability tensors, and different types of computational meshes. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Novel properties of wave propagation in biaxially anisotropic left-handed materials

ANNALEN DER PHYSIK, Issue 6 2004
J.Q. Shen
Abstract Some physically interesting properties and effects (including the quantum effects) of wave propagation in biaxially anisotropic left-handed materials are investigated in this paper: (i) we show that in the biaxially gyrotropic left-handed material, the left-right coupling of circularly polarized light arises due to the negative indices in permittivity and permeability tensors of gyrotropic media; (ii) it is well known that the geometric phases of photons inside a curved fiber in previous experiments often depend on the cone angles of solid angles subtended by a curve traced by the direction of wave vector of light, at the center of photon momentum space. Here, however, for the light propagating inside certain anisotropic left-handed media we will present a different geometric phase that is independent of the cone angles; (iii) the extra phases of electromagnetic wave resulting from the instantaneous helicity inversion at the interfaces between left- and right-handed (LRH) media is also studied in detail by using the Lewis-Riesenfeld invariant theory. Some interesting applications (e.g., controllable position-dependent frequency shift, detection of quantum-vacuum geometric phases and helicity reversals at the LRH interfaces etc.) of above effects and phenomena in left-handed media is briefly discussed. [source]

Anisotropic Variation Law of Rock Permeability with the Burial Depth of Limestone

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2003
TIAN Kaiming
Abstract, Permeability tensors of both macrofracture and microfracture systems were measured progressively along the depth of limestone formations at severed sites. It was found that the principal permeability values Kx, Ky and Kz in these permeability tensors all decrease simultaneously and logarithmically with depth. However, the limestone aquifers are composed of an upper region where the larger permeability ellipsoid is upright or prolate and characterized by KzKx and Kz>Ky, a transitional zone, and a lower zone whose smaller permeability ellipsoid is horizontal or oblate and characterized by Kzpermeability tensors in a macrofracture system displays a similar pattern with that in a microfracture system. It is next to impossible to examine the rock permeability tensor of the aquifer just by measuring the hydraulic parameters of macrofracture system directly, unless the limestone aquifer is exposed on or near the earth's surface. Therefore, the permeability tensors of a macrofracture system at any depth may be indirectly and roughly determined from the gaugeable permeability tensors of the microfracture system by conversion. This anisotropic variation law of rock permeability with depth is of great significance in the study of three-dimensional fracture water flow the huge carbonate formations and in the research on the conditions of karst development and karst distribution. [source]