Effects of the geometry of two‐dimensional fractures on their hydraulic aperture and on the validity of the local cubic law

Flow through rough fractures is investigated numerically in order to assess the validity of the local cubic law for different fracture geometries. Two‐dimensional channels with sinusoidal walls having different geometrical properties defined by the aperture, the amplitude, and the wavelength of the walls' corrugations, the corrugations asymmetry, and the phase shift between the two walls are considered to represent different fracture geometries. First, it is analytically shown that the hydraulic aperture clearly deviates from the mean aperture when the walls' roughness, the phase shift, and/or the asymmetry between the fracture walls are relatively high. The continuity and the Navier–Stokes equations are then solved by means of the finite element method and the numerical solutions compared to the theoretical predictions of the local cubic law. Reynolds numbers ranging from 0.066 to 66.66 are investigated so as to focus more particularly on the effect of flow inertial effects on the validity of the local cubic law. For low Reynolds number, typically less than 15, the local cubic law properly describes the fracture flow, especially when the fracture walls have small corrugation amplitudes. For Reynolds numbers higher than 15, the local cubic law is valid under the conditions that the fracture presents a low aspect ratio, small corrugation amplitudes, and a moderate phase lag between its walls.     

About Darcy's law in non-Galilean frame

This paper is aimed towards investigating the filtration law of an incompressible viscous Newtonian fluid through a rigid non-inertial porous medium (e.g. a porous medium placed in a centrifuge basket). The filtration law is obtained by upscaling the flow equations at the pore scale. The upscaling technique is the homogenization method of multiple scale expansions which rigorously gives the macroscopic behaviour and the effective properties without any prerequisite on the form of the macroscopic equations. The derived filtration law is similar to Darcy's law, but the tensor of permeability presents the following remarkable properties: it depends upon the angular velocity of the porous matrix, it verifies Hall–Onsager's relationship and it is a non-symmetric tensor. We thus deduce that, under rotation, an isotropic porous medium leads to a non-isotropic effective permeability. In this paper, we present the results of numerical simulations of the flow through rotating porous media. This allows us to highlight the deviations of the flow due to Coriolis effects at both the microscopic scale (i.e. the pore scale), and the macroscopic scale (i.e. the sample scale). The above results confirm that for an isotropic medium, phenomenological laws already proposed in the literature fails at reproducing three-dimensional Coriolis effects in all types of pores geometry. We show that Coriolis effects may lead to significant variations of the permeability measured during centrifuge tests when the inverse Ekman number Ek⁻¹ is 𝒪(1). These variations are estimated to be less than 5% if Ek⁻¹<0.2, which is the case of classical geotechnical centrifuge tests. We finally conclude by showing that available experimental data from tests carried out in centrifuges are not sufficient to determining the effective tensor of permeability of rotating porous media. Copyright © 2004 John Wiley & Sons, Ltd.     

钱二块铀矿床采铀注液结垢趋势的理论分析与预测

用离子系数矩阵法对钱二块铀矿床地浸采铀试验注液中存在的独立离子反应进行了确定,由溶度积规则及反应平衡原理,借助Matlab编程,估算出了钱二块铀矿床地浸采铀试验注液可能会生成的沉淀物种类及数量,为防治结垢提供了一定的理论依据.     

从国际司法判例和国际海洋法看中日海洋区域的划界

《联合国海洋法公约》规定，海洋划界争端应在有关国际法的基础上，以和平的方式加以解决，中、日两国的海洋介应该按照国际法的规定，找到适合两国情况的比较公平的原则和方法。     

Comprehensive development of agriculture in the Loess Plateau Area

The Loess Plateau is one of China s developing areas where socio-econ-omy is backward, ecological environment deteriorated and people's life difficult.The purpose of carrying out comprehensive development of the area's agriculture is, in essence, to open up new fields of agro-production, to intensify the utilization of related resources, to raise productivity and to win bigger output. The decision is important, as by so doing, the physical landscape could be tranformed, the local economy could be flourished, and the people's standard of living could be improved, and moreover the national development strategy of "depending on the East and shifting to the West" and building Shanxi Province into an energy and chemical industrial base could be realized.Based on field investigations in recent years, the auther proposed the purpose, target, principles, steps, tactics and strategies for the comprehensive development of the are's agriculture.     

浅谈档案行政执法和档案普法的关系

本文根据《中华人民共和国档案法》及有关档案法律法规,论述了档案行政执法和档案普法的关系。     

华南海西—印支期成矿地质背景

华南海西—印支成矿期内,成矿序列完整,类型齐全,矿种繁多,为其它成矿期所莫及。沉积矿床需要稳定的地质背景,层控矿床形成的较有利的地质背景是稳中有动。