scholarly journals Effect of Bentonite on the Coefficient of Consolidation of Soil

2021 ◽  
Vol 9 (9) ◽  
pp. 1230-1233
Keyword(s):  
Volcanic Ash ◽  
Applied Pressure ◽  
Percentage Increase ◽  
Collective Effect ◽  
Open Spaces ◽  
Coefficient Of Consolidation ◽  
Rate Of Increase ◽  
Fine Clay ◽  
Flow Through ◽  
High Absorption

Bentonite is a fine clay, usually occurring as a byproduct of atmospheric weathering of volcanic ash. It is widely known for its capabilities of high absorption of moisture, and swelling, as a result of moisture contact. Bentonite has a crystalline structure with the main constituent as montmorillonite which has a dual-layered structure. It is the main ingredient responsible for imparting valuable properties to bentonite. In this study, several samples were tested from different regions of district Mardan, Pakistan, to analyze the collective effect of bentonite on the region’s soil. An analysis was conducted based on the performed tests on the samples, to predict the consolidation behavior when samples were replaced with 0%, 5%, 10%, and 15% of bentonite by mass. Thecoefficient of consolidation gives the rate of increase of settlement or consolidation when the sample is subjected to externally applied pressure. This study observed a decrease in the coefficient of consolidation of soil with the percentage increase of bentonite reaching a minimum value of 0.005 in2/min showing about four times decrease in the coefficient of consolidation with 15% replacement of soil with bentonite. This behavior of bentonite is attributed to the fact that; being a fine clay, its addition to the soil reduces its pores and fills the open spaces, hence reducing the chances of fluid to penetrate or flow through the soil, resulting in the reduction ofthe coefficient of consolidation Cv.

scholarly journals Mathematical study on two-fluid model for flow of K–L fluid in a stenosed artery with porous wall

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
R. Ponalagusamy ◽  
Ramakrishna Manchi
Keyword(s):  
Theoretical Study ◽  
Fluid Model ◽  
Porous Wall ◽  
Governing Equations ◽  
Rate Of Increase ◽  
Special Cases ◽  
Stenosed Artery ◽  
Flow Through ◽  
Two Fluid Model ◽  
Two Fluid

AbstractThe present communication presents a theoretical study of blood flow through a stenotic artery with a porous wall comprising Brinkman and Darcy layers. The governing equations describing the flow subjected to the boundary conditions have been solved analytically under the low Reynolds number and mild stenosis assumptions. Some special cases of the problem are also presented mathematically. The significant effects of the rheology of blood and porous wall of the artery on physiological flow quantities have been investigated. The results reveal that the wall shear stress at the stenotic throat increases dramatically for the thinner porous wall (i.e. smaller values of the Brinkman and Darcy regions) and the rate of increase is found to be 18.46% while it decreases for the thicker porous wall (i.e. higher values of the Brinkman and Darcy regions) and the rate of decrease is found to be 10.21%. Further, the streamline pattern in the stenotic region has been plotted and discussed.

An Intensity Demodulated Refractive Index Sensor Based on A Hollow-Core Anti-Resonant Fiber

2022 ◽  
Author(s):  
Shidi Liu ◽  
Tianyu Yang ◽  
Liang Zhang ◽  
Ming Tian ◽  
Yuming Dong
Keyword(s):  
Refractive Index ◽  
Structural Parameters ◽  
High Sensitivity ◽  
Refractive Index Sensor ◽  
Hollow Core ◽  
Promising Candidate ◽  
Mid Infrared ◽  
Flow Through ◽  
Demodulation Method ◽  
High Absorption

Abstract A robust and simple mid-infrared hollow-core anti-resonant fiber (ARF) based refractive index (RI) sensor with an intensity demodulation method is presented and analyzed for monitoring liquid analytes. The ARF allows liquid analytes to flow through its hollow area for detection. To obtain ideal sensing performance, an epsilon negative (ENG) material is introduced into the selected anti-resonant tube. With the high absorption of the ENG material, only one fundamental mode is available for detection and is sensitive to the RI variation of analytes. Moreover, the effects of structural parameters on the sensing performances are discussed and analyzed to further understand the mechanism and optimization. The final result shows that the ARF sensor can exhibit a high sensitivity of -372.58 dB/RIU at a fixed wavelength within a broad RI range from 1.33 to 1.45, which covers most liquid analytes. It is a promising candidate for chemical and environmental analysis. Additionally, it has the potential for deep research to feed diverse applications.

Lymphatic regulation of hematocrit during hypoxia in the toad Bufo woodhousei

1995 ◽  
Vol 269 (4) ◽  
pp. R814-R821 ◽  
Author(s):  
G. M. Malvin ◽  
S. Macias ◽  
M. Sanchez ◽  
R. Dasalla ◽  
A. Park ◽  
...  
Keyword(s):  
Plasma Volume ◽  
Lymph Flow ◽  
Cholinergic Nerves ◽  
Arterial Blood ◽  
Rate Of Increase ◽  
Lymph Heart ◽  
Flow Through ◽  
Bufo Woodhousei ◽  
Induced Changes ◽  
Toad Bufo

Hypoxia rapidly increases hematocrit (Hct) in anuran amphibians by reducing plasma volume, but the mechanism(s) mediating this response is unknown. We tested the hypothesis that, during hypoxia, plasma volume is reduced by impaired lymph heart (LH) function, decreasing lymph flow into the circulation. In Bufo woodhousei, we measured the effects of hypoxia on Hct, lymph heart rate (LHR), LH pressure, the movement of dye from the dorsal lymph sac to the arterial blood, and flow through an open LH cannula. We also tested whether splenic contraction or cholinergic nerves contribute to the hypoxia-induced changes. Graded hypoxia between 21 and 4% O2 produced graded increases in Hct (P < 0.0001) and decreases in LHR (P = 0.01). Hypoxia reduced the rate of increase in arterial Evans blue concentration after injection into the dorsal lymph sac (P = 0.041) and decreased flow through an open LH cannula (P < 0.012). Hypoxia increased Hct and reduced LHR similarly in control, splenectomized, and sham-splenectomized toads. Atropine had no significant effect on Hct and LHR. These results indicate that the LHs play a regulatory role in hypoxia-induced hemoconcentration.

Prediction of Local Losses of Low Re Flows in Elastic Porous Media

2017 ◽  
Author(s):  
Sid M. Becker ◽  
Stefan Gasow
Keyword(s):  
Porous Media ◽  
Flow Field ◽  
Stokes Equations ◽  
Applied Pressure ◽  
Porous Matrix ◽  
Pore Geometry ◽  
Test Case ◽  
Hydraulic Permeability ◽  
Local Pressure ◽  
Flow Through

An isotropic elastic porous structure whose pore geometry is regular (periodically uniform) will experience non-uniform deformation when a viscous fluid flows through the matrix under the influence of an externally applied pressure difference. In such a case, the flow field will experience a non-uniform pressure gradient whose magnitude increases in the direction of bulk flow. In this study, a method is presented that predicts local losses of the flow through a porous matrix whose geometry varies in the direction of flow. Employing an asymptotic expansion about the variation in geometry provides an expression relating local hydraulic permeability to local pore geometry. In this way the pressure field is able to be determined without requiring the explicit solution of the flow field. In this study a test case is presented showing that the local pressure losses are predicted to be within 0.5% of the losses determined from the solution to the Navier-Stokes Equations. The approach can be used to simplify the coupled fluid-solid problem of flow through elastic porous media by replacing the need to explicitly solve the flow field.

Flow Through a Deformable Porous Material

1975 ◽  
Vol 42 (3) ◽  
pp. 598-602 ◽  
Author(s):  
G. S. Beavers ◽  
T. A. Wilson ◽  
B. A. Masha
Keyword(s):  
Porous Material ◽  
Incompressible Fluid ◽  
Applied Pressure ◽  
Local Stress ◽  
Darcy Law ◽  
Stress Dependence ◽  
One Dimensional ◽  
Flow Through ◽  
Incompressible Media ◽  
The One

A model is presented to describe the one-dimensional flow of an incompressible fluid through a deformable porous material. The model is based on the Forchheimer extension of the Darcy law for flows through incompressible media, where the Forchheimer coefficients are functions of the local stress. Experiments to determine the stress-dependence of the coefficients for polyurethane foam specimens are described. The coefficients are then used in the model to predict the mass flow rate through long polyurethane specimens as a function of the applied pressure difference across the material. The predictions of the model are compared with experimental observations.

AN ANALYTICAL MODEL FOR TWO-PHASE RELATIVE PERMEABILITY WITH JAMIN EFFECT IN POROUS MEDIA

Fractals ◽  
2018 ◽  
Vol 26 (03) ◽  
pp. 1850037 ◽  
Author(s):  
MINGCHAO LIANG ◽  
YINHAO GAO ◽  
SHANSHAN YANG ◽  
BOQI XIAO ◽  
ZHANKUI WANG ◽  
...  
Keyword(s):  
Porous Media ◽  
Relative Permeability ◽  
Pressure Difference ◽  
Applied Pressure ◽  
Fractal Model ◽  
Low Permeability ◽  
Two Phase ◽  
Low Permeability Reservoir ◽  
Model Predictions ◽  
Flow Through

Jamin effect, which is a capillary pressure obstructing the drop/bubble flow through the narrow throat, has an important effect on the multiphase flow in the low permeability reservoir porous media. In this work, a novel model for the relative permeability with Jamin effect is developed to study the two-phase flow through porous media based on the fractal theory. The proposed relative permeability is expressed as a function of the applied pressure difference, shape parameters of the drop/bubble, the physical parameters of the wetting and nonwetting fluids, and microstructural parameters of porous media. Good agreement between model predictions and available experimental data is obtained, and the advantage of the present fractal model can be highlighted by comparisons with the empirical model predictions. Additionally, the influences of Jamin effect on the two-phase relative permeability are discussed comprehensively and in detail. The model reveals that the length ratios ([Formula: see text] and [Formula: see text]) have significant effects on the relative permeabilities. It is also found that the nonwetting phase relative permeability strongly depends on the interfacial tension, applied pressure difference, viscosity ratio and porosity of porous media at the lower wetting phase saturation. Furthermore, the fractal model will shed light on the two-phase transport mechanism of the low permeability reservoir porous media.

Investigation and Separation of Turbulent Fluctuations in Airborne Measurements of Volcanic Ash with Optical Particle Counters

2016 ◽  
Vol 11 (1) ◽  
pp. 72-84 ◽  
Author(s):  
Jonas Elíasson ◽  
◽  
Konradin Weber ◽  
Andreas Vogel Thorgeir Pálsson ◽  
Junichi Yoshitani ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Environmental Science ◽  
Environmental Parameters ◽  
Aviation Industry ◽  
Random Disturbance ◽  
Airborne Measurements ◽  
Turbulent Fluctuations ◽  
Rate Of Increase ◽  
Measurement Series ◽  
Turbulence Parameters

The science of measuring airborne volcanic ash concentrations supports research in such fields as atmospheric environmental science and the modeling of atmospheric pollution from volcanoes, and is thus very valuable to the aviation industry. These measurements show large scatter directly traceable to turbulent fluctuations responsible for diffusing volcanic dust. Before semistationary components in observations can be compared to each other or to simulation results, they must be separated from fluctuations. In the design of the separation process, however, neither seasonal or diurnal periodicity nor random disturbance with known properties exists to serve as a guideline. It has been suggested that fluctuations could be eliminated through repeated convolutions of a simple 3-point filter enough times. The number of convolutions is chosen from the change in the rate of increase of a special variability parameter. When semistationary concentrations are separated from fluctuations, their statistics are compared to turbulence parameters and the autocorrelation of the series. The method is demonstrated using three measurement series from Sakurajima, Japan measured in 2013. It is concluded that this new method is simple and trustworthy where knowledge and experience of the environmental parameters can be utilized to support the results. They indicate a variability of 40% in the relative fluctuations of the PM10 and around 20% of the PM2.5. The relative fluctuations may be considered completely random, but normally distributed rather than a white noise with an evenly distributed variance spectrum.

Flow Characterization of Microfluidic Paper-Based Analytical Devices With Hollow Channels

2019 ◽  
Author(s):  
Haipeng Zhang ◽  
Danielle Barmore ◽  
Sangjin Ryu
Keyword(s):  
Liquid Flow ◽  
Pressure Difference ◽  
Point Of Care ◽  
Applied Pressure ◽  
Flow Characteristics ◽  
Cost Effective ◽  
Theoretical Models ◽  
Flow Speed ◽  
Liquid Sample ◽  
Flow Through

Abstract Microfluidic paper-based analytical devices (μPADs) are cost-effective point-of-care diagnostic devices. μPADs consist of porous filter paper patterned with hydrophobic solid ink barriers to create flow channels. Because a liquid sample flows through the paper channel driven by capillary force, the resultant flow is usually slow. To overcome this limitation, a hollow channel can be added to a μPAD to increase the flow speed significantly. The liquid flow through the hollow channel is known to be driven by a pressure difference between the inlet and outlet of the device. Accordingly, theoretical models have been proposed to understand and predict flow characteristics of μPADs with hollow channels. The goal of this study is to experimentally characterize liquid flow through μPADs having a hollow channel, by investigating relationships among the travel distance of the liquid front through the μPADs, the applied pressure difference, and the dimension of the hollow channel. Thus, the outcome of this study would contribute to validating the theoretical models and enable better control of liquid sample flow in μPADs with hollow channels.

Sign in / Sign up

Export Citation Format

Share Document