ON THE THEORY OF FLOW OF UNDERGROUND FLUIDS IN COMPRESSIBLE STRATA

1959 ◽  
Vol 37 (3) ◽  
pp. 276-284
Author(s):  
A. E. Scheidegger
Keyword(s):  
Porous Medium ◽  
Vertical Direction ◽  
Complex Problem ◽  
Flow Equation ◽  
Local Anisotropy ◽  
Local Isotropy ◽  
Differential Flow ◽  
Considerable Simplification ◽  
General Geometry ◽  
Made In

The problem of flow of a fluid within a compressible porous medium is investigated. It is shown that in general, the motion of the fluid cannot be separated from that of the medium. This leads to a very complex problem of consolidation. However, considerable simplification can be made in applications to the flow of underground fluids. In that case, the general geometry of the consolidation can be predicted since the latter can take place in the vertical direction only. Furthermore, in many cases it is possible to neglect the volume compressibility of the porous matrix.Two cases have been considered: that of local isotropy of stress and permeability and that of local anisotropy of these two quantities. The basic differential flow equation for the two cases is deduced.

scholarly journals Numerical Modeling of Water Flow in Expansive Soils with Simplified Description of Soil Deformation

2018 ◽  
Vol 65 (4) ◽  
pp. 301-313
Author(s):  
Sławomir Michalski ◽  
Adam Szymkiewicz
Keyword(s):  
Water Flow ◽  
Unsaturated Flow ◽  
Expansive Soils ◽  
Vertical Direction ◽  
Time Discretization ◽  
Soil Mass ◽  
Flow Equation ◽  
Anthropogenic Factors ◽  
Equilibrium Equations ◽  
Stress Equilibrium

AbstractIn this paper we describe a numerical model of transient water flow in unsaturated expansive soils and the resulting soil volume change. The unsaturated flow equation is solved in a 2D domain using a finite-volume method and an explicit time discretization scheme. Strains in the soil mass are calculated by two simplified approaches, assuming that the strain state is either 1D (in the vertical direction only) or 2D with equal strains in horizontal and vertical directions. The model is applied to two cases described in the literature, in which the strains were computed from the solution of the stress equilibrium equation. It is shown that the simplified methods give results which are reasonably close to the more complex approach based on the equilibrium equations. The proposed model can be used to predict time-varying soil shrinkage and swelling caused by natural and anthropogenic factors.

Characteristics of vorticity fluctuations in a turbulent wake

1988 ◽  
Vol 189 ◽  
pp. 349-365 ◽  
Author(s):  
R. A. Antonia ◽  
L. W. B. Browne ◽  
D. A. Shah
Keyword(s):  
Circular Cylinder ◽  
Turbulent Wake ◽  
Probability Density Functions ◽  
The Self ◽  
Density Functions ◽  
Streamwise Vorticity ◽  
Local Isotropy ◽  
Vorticity Component ◽  
Vorticity Fluctuation ◽  
Made In

Measurements of the lateral components of the vorticity fluctuation have been made in the self-preserving turbulent wake of a circular cylinder. Each component was obtained separately using two X-wires separated in the appropriate lateral directions. The two velocity derivatives which make up the streamwise vorticity component were also determined but not simultaneously. An approximation to the streamwise vorticity was made from these measurements. Moments, probability density functions and spectra of the three vorticity components across the wake are presented and discussed. The high-wavenumber behaviour of the spectra is compared with calculations, based on local isotropy. Satisfactory agreement with the calculations is obtained for the lateral vorticity components over a significant high-wavenumber range. The approximated streamwise vorticity spectrum tends towards the isotropic calculation at very large wavenumbers.

scholarly journals Polarization Changes of Radio Signals in Vertical Radio-Echo Sounding of Glaciers

1975 ◽  
Vol 15 (73) ◽  
pp. 469-470 ◽  
Author(s):  
V. V. Bogorodskiy ◽  
G. V. Trepov ◽  
B. A. Fedorov
Keyword(s):  
Crystal Structure ◽  
Vertical Direction ◽  
Main Method ◽  
Receiving Antenna ◽  
Linearly Polarized ◽  
Radio Echo Sounding ◽  
Radio Signals ◽  
Interference Signals ◽  
Elliptically Polarized ◽  
Made In

An electromagnetic linearly-polarized signal transmitted through the glacier in a vertical direction, reflected from the bedrock, and received with a receiving antenna, is found to be changed into one either partially or elliptically polarized. The polarization changes are believed to be due mainly to the crystal structure of the glacier and anisotropy caused by the pressure of the upper layers. An analysis of the polarization diagrams obtained is up to the present the main method used for studies of the reflected signal polarization. Evidently using a simple dipole a partially-polarized signal is not distinguishable from one that is elliptically polarized, nor is a nonpolarized signal distinguished from circularly polarized. However, the data recently obtained are of great importance, particularly from studies of glacier crystal structure made in deep core drilling. Possible reasons for the polarization changes of the signal have been analysed. Results of the analyses of the polarization diagrams obtained both at individual points and along extended traverses are discussed. It has been found that the signal reflected from a considerable ice thickness is polarized in such a way that the parallel orientation of the receiving and transmitting dipoles can be disregarded. En route recordings of the signal fluctuations obtained by parallel and orthogonally polarized dipoles are shown. The results of polarization studies are important for practical purposes. For example, bedrock relief sounding carried out with crossed dipoles makes it possible to get rid of interference signals occurring due to scattering from inhomogeneous structures of the upper part of the glacier.

Free Convective Heat and Mass Transfer in a Doubly Stratified Non-Darcy Porous Medium

2006 ◽  
Vol 128 (11) ◽  
pp. 1204-1212 ◽  
Author(s):  
P. A. Lakshmi Narayana ◽  
P. V. S. N. Murthy
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Vertical Direction ◽  
Vertical Surface ◽  
Transfer Coefficients ◽  
Double Stratification ◽  
Complex Interactions ◽  
Inertia Parameter

Free convective heat and mass transfer from a vertical surface embedded in a doubly stratified non-Darcy porous medium has been analyzed. The wall temperature and concentration are constant and the medium is linearly stratified in the vertical direction with respect to both temperature, and concentration. A series approximation is made for stream function, temperature, and concentration in terms of the stratification parameter. The flow, temperature, and concentration fields are affected by the complex interactions among the diffusion ratio Le, buoyancy ratio N and stratification ratio Sr in addition to the inertia parameter Fc. The effect of double stratification of the medium on nondimensional heat and mass transfer coefficients is discussed.

scholarly journals Methane and Carbon Dioxide Hydrate Formation and Dissociation in Presence of a Pure Quartz Porous Framework Impregnated with CuSn12 Metallic Powder: An Experimental Report

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5115 ◽  
Author(s):  
Alberto Maria Gambelli ◽  
Giulia Stornelli ◽  
Andrea Di Schino ◽  
Federico Rossi
Keyword(s):  
Carbon Dioxide ◽  
Porous Medium ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Metallic Powder ◽  
Equilibrium Curve ◽  
Hydrate Dissociation ◽  
Porous Framework ◽  
Made In ◽  
The Ideal

Hydrate formation and dissociation processes were carried out in the presence of a pure quartz porous medium impregnated with a metallic powder made with a CuSn12 alloy. Experiments were firstly made in the absence of that powder; then, different concentrations were added to the porous medium: 4.23 wt.%, 18.01 wt.%, and 30.66 wt.%. Then, the hydrate dissociation values were compared with those present in the literature. The porous medium was found to act as an inhibitor in the presence of carbon dioxide, while it did not alter methane hydrate, whose formation proceeded similarly to the ideal trend. The addition of CuSn12 promoted the process significantly. In particular, in concentrations of up to 18.01 wt.%, CO2 hydrate formed at milder conditions until it moved below the ideal equilibrium curve. For methane, the addition of 30.66 wt.% of powder significantly reduced the pressure required to form hydrate, but in every case, dissociation values remained below the ideal equilibrium curve.

scholarly journals Why society is a complex problem? A review of Philip Ball’s book – Meeting Twenty-first Century Challenges with a New Kind of Science

2013 ◽  
Vol 2 (1) ◽  
pp. 80
Author(s):  
Diana Tampu ◽  
Carmen Costea
Keyword(s):  
Complex Problem ◽  
First Century ◽  
Global Changes ◽  
Economic Activities ◽  
Social Phenomena ◽  
Complex Interactions ◽  
The Moment ◽  
The Right ◽  
Bear Witness ◽  
Made In

The 21st century is burdened by a series of dramatic changes and efforts are carried out to find potential solutions to consumerism, access to information, transient climate disequilibria, health care and demographic transformations. A new page in human history will bear witness to the introduction of new ways of thinking, new changes, new relationships and interconnections that transcend states and societies. The moment is ripe for individuals aware of the implications carried by global changes and challenges, to step up and encourage responsibility and sustainable development. Mankind is currently living in a data-rich world, where information is widely dispersed. Nevertheless, extracting the right assumptions and conclusions from the available data proves difficult as numerous social phenomena do not run with clockwork precision as the laws governing the Newtonian universe.Human awareness and intelligence demand a more responsible approach to all operations and steps should be made in determining the consequences and their impact. The goal of this paper is not restricted to providing a review but also to enforce certain ideas in relation to the complex interactions specific to society and economic activities.

scholarly journals Perception of vibrotactile distance on the back

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Myrthe A. Plaisier ◽  
Lotte I. N. Sap ◽  
Astrid M. L. Kappers
Keyword(s):  
Distance Perception ◽  
Vertical Direction ◽  
The Other ◽  
Horizontal Direction ◽  
Baseline Condition ◽  
Sensory Substitution ◽  
Vibrotactile Stimulation ◽  
Horizontal Orientation ◽  
Vibrotactile Perception ◽  
Made In

Abstract Vibrotactile displays worn on the back can be used as sensory substitution device. Often vibrotactile stimulation is chosen because vibration motors are easy to incorporate and relatively cheap. When designing such displays knowledge about vibrotactile perception on the back is crucial. In the current study we investigated distance perception. Biases in distance perception can explain spatial distortions that occur when, for instance, tracing a shape using vibration. We investigated the effect of orientation (horizontal vs vertical), the effect of positioning with respect to the spine and the effect of switching vibration motors on sequentially versus simultaneously. Our study includes four conditions. The condition which had a horizontal orientation with both vibration motors switching on sequentially on the same side of the spine was chosen is the baseline condition. The other three conditions were compared to this baseline condition. We found that distances felt longer in the vertical direction than in the horizontal direction. Furthermore, distances were perceived to be longer when vibration motors were distributed on both sides of the spine compared to when they were on the same side. Finally, distances felt shorter when vibration motors were switched on simultaneously compared to sequentially. In the simultaneous case a distance of 4 cm was not clearly perceived differently than a distance of 12 cm. When designing vibrotactile displays these anisotropies in perceived distance need to be taken into account because otherwise the intended shape will not match the perceived shape. Also, dynamically presented distances are more clearly perceived than static distances. This finding supports recommendations made in previous studies that dynamic patterns are easier to perceive than static patterns.

scholarly journals Horizontally isotropic double porosity convection

2019 ◽  
Vol 475 (2221) ◽  
pp. 20180672 ◽  
Author(s):  
B. Straughan
Keyword(s):  
Porous Medium ◽  
Nonlinear Stability ◽  
Vertical Component ◽  
Vertical Direction ◽  
Transversely Isotropic ◽  
Double Porosity ◽  
Solid Skeleton ◽  
The Difference

We analyse instability and nonlinear stability in a layer of saturated double porosity medium. In a double porosity or bidisperse porous medium, there are normal pores which give rise to a macroporosity. But, there are also cracks or fissures in the solid skeleton and these give arise to another porosity known as micro porosity. In this paper, the macropermeability is horizontally isotropic, in the sense that the vertical component of permeability is different to the horizontal one which is the same in all horizontal directions. Thus, the permeability is transversely isotropic with the isotropy axis in the vertical direction of gravity. We also allow the micro permeability to be horizontally isotropic, but the permeability ratios of vertical to horizontal are different in the macro- and micro-phases. The effect of the difference of ratios is examined in detail.

scholarly journals Solutions for groundwater flow with sloping stream boundary: analytical, numerical and experimental models

2017 ◽  
Vol 49 (4) ◽  
pp. 1120-1130 ◽  
Author(s):  
Uğur Boyraz ◽  
Cevza Melek Kazezyılmaz-Alhan
Keyword(s):  
Surface Water ◽  
Groundwater Flow ◽  
Laboratory Experiments ◽  
Groundwater Resources ◽  
Experimental Models ◽  
Flow Equation ◽  
Visual Modflow ◽  
Aquifer System ◽  
Aquifer Characteristics ◽  
Made In

Abstract Protecting groundwater resources plays an important role in watershed management. For this purpose, studies on groundwater flow dynamics incorporating surface water–groundwater interactions have been conducted including analytical, numerical, and experimental models. In this research, a stream–aquifer system was considered to understand the physical behavior of surface water–groundwater interactions. Interactions in a stream–aquifer system were incorporated into the mathematical modeling by defining the stream head as a boundary condition for the groundwater flow equation. This boundary was chosen as a sloping stream boundary, which is an approach in representing the natural conditions of the stream and may be used to define continuous interactions between stream and aquifer. A semi-analytical solution for transient 2D groundwater flow was developed for the considered problem. Isotropic, homogeneous, and finite aquifer assumptions were made in order to define the aquifer characteristics. Then, a series of laboratory experiments was conducted to simulate this stream–aquifer system. Finally, a numerical model was developed by using Visual MODFLOW to verify analytical and experimental results. Numerical results matched with both analytical solutions and the experimental observations.

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