scholarly journals Preferential flow systems amended with biogeochemical components: imaging of a two-dimensional study

2018 ◽  
Vol 22 (4) ◽  
pp. 2487-2509 ◽  
Author(s):  
Ashley R. Pales ◽  
Biting Li ◽  
Heather M. Clifford ◽  
Shyla Kupis ◽  
Nimisha Edayilam ◽  
...  
Keyword(s):  
Light Transmission ◽  
Water Saturation ◽  
Solution Concentration ◽  
Unstable Flow ◽  
Transmission Method ◽  
Control Solution ◽  
Soil Component ◽  
Finger Width ◽  
Plant Exudates ◽  
Soil Components

Abstract. The vadose zone is a highly interactive heterogeneous system through which water enters the subsurface system by infiltration. This paper details the effects of simulated plant exudate and soil component solutions upon unstable flow patterns in a porous medium (ASTM silica sand; US Silica, Ottawa, IL, USA) through the use of two-dimensional tank light transmission method (LTM). The contact angle (θ) and surface tension (γ) of two simulated plant exudate solutions (i.e., oxalate and citrate) and two soil component solutions (i.e., tannic acid and Suwannee River natural organic matter, SRNOM) were analyzed to determine the liquid–gas and liquid–solid interface characteristics of each. To determine if the unstable flow formations were dependent on the type and concentration of the simulated plant exudates and soil components, the analysis of the effects of the simulated plant exudate and soil component solutions were compared to a control solution (Hoagland nutrient solution with 0.01 M NaCl). Fingering flow patterns, vertical and horizontal water saturation profiles, water saturation at the fingertips, finger dimensions and velocity, and number of fingers were obtained using the light transmission method. Significant differences in the interface properties indicated a decrease between the control and the plant exudate and soil component solutions tested; specifically, the control (θ= 64.5∘ and γ= 75.75 mN m−1) samples exhibited a higher contact angle and surface tension than the low concentration of citrate (θ= 52.6∘ and γ= 70.8 mN m−1). Wetting front instability and fingering flow phenomena were reported in all infiltration experiments. The results showed that the plant exudates and soil components influenced the soil infiltration as differences in finger geometries, velocities, and water saturation profiles were detected when compared to the control. Among the tested solutions and concentrations of soil components, the largest finger width (10.19 cm) was generated by the lowest tannic acid solution concentration (0.1 mg L−1), and the lowest finger width (6.00 cm) was induced by the highest SRNOM concentration (10 mg L−1). Similarly, for the plant exudate solutions, the largest finger width (8.36 cm) was generated by the lowest oxalate solution concentration (0.1 mg L−1), and the lowest finger width (6.63 cm) was induced by the lowest citrate concentration (0.1 mg L−1). The control solution produced fingers with average width of 8.30 cm. Additionally, the wettability of the medium for the citrate, oxalate, and SRNOM solutions increased with an increase in concentration. Our research demonstrates that the plant exudates and soil components which are biochemical compounds produced and released in soil are capable of influencing the process of infiltration in soils. The results of this research also indicate that soil wettability, expressed as (cos θ)1∕2, should be included in the scaling of the finger dimension, i.e., finger width, when using the Miller and Miller (1956) scaling theory for the scaling of flow in porous media.

scholarly journals Preferential Flow Systems Amended with Biogeochemical Components: Imaging of a Two-Dimensional Study

2017 ◽  
Author(s):  
Ashley R. Pales ◽  
Biting Li ◽  
Heather M. Clifford ◽  
Shyla Kupis ◽  
Nimisha Edayilam ◽  
...  
Keyword(s):  
Porous Media ◽  
Preferential Flow ◽  
Light Transmission ◽  
Water Saturation ◽  
Silica Sand ◽  
Two Dimensional ◽  
Unstable Flow ◽  
Transmission Method ◽  
Soil Component ◽  
Plant Exudates

Abstract. The vadose zone is a highly interactive heterogeneous system through which water enters into the subsurface system by infiltration. This paper details the effects of simulated plant exudate and soil component solutions upon unstable flow patterns in a porous media (ASTM silica sand; US Silica, Ottawa, IL, USA) through the use of two-dimensional (2D) tank light transmission method (LTM). The contact angle and surface tension of two simulated plant exudate solutions (i.e. oxalate, and citrate) and two soil component solutions (i.e. tannic acid, and Suwannee River Natural Organic Matter) were analyzed to determine the liquid-gas and liquid-solid interface characteristics of each. To determine if the unstable flow formations were dependent on the type and concentration of the simulated plant exudates and soil components, the analysis of the effects of the simulated plant exudate and soil component solutions were compared to a control rainwater solution. The differences in the fingering flow were quantified with the finger geometries, the velocity of finger propagation, the vertical and horizontal water saturation profiles, and the water saturation at the fingertips. Significant differences in the interface processes indicated a decrease between the control and the plant exudate and soil component solutions tested; specifically, the control at 64.5 θ and 75.75 Nm/m, to the low concentration of citrate at 52.6 θ and 70.8 Nm/m. The changes in finger geometries and velocity of propagation between the control solution and the simulated plant exudate and soil component solutions further demonstrate that the plant exudates increased the wettability and mobility of the solutions during the infiltration process in unsaturated porous media.

scholarly journals The Dependence of Electrical Resistivity-Saturation Relationships on Multiphase Flow Instability

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zoulin Liu ◽  
Stephen M. J. Moysey
Keyword(s):  
Electrical Resistivity ◽  
Multiphase Flow ◽  
Light Transmission ◽  
Flow Instability ◽  
Water Saturation ◽  
Bond Number ◽  
Smooth Transition ◽  
Transmission Method ◽  
Archie’S Law ◽  
Fluid Saturation

We investigate the relationship between apparent electrical resistivity and water saturation during unstable multiphase flow. We conducted experiments in a thin, two-dimensional tank packed with glass beads, where Nigrosine dyed water was injected uniformly along one edge to displace mineral oil. The resulting patterns of fluid saturation in the tank were captured on video using the light transmission method, while the apparent resistivity of the tank was continuously measured. Different experiments were performed by varying the water application rate and orientation of the tank to control the generalized Bond number, which describes the balance between viscous, capillary, and gravity forces that affect flow instability. We observed the resistivity index to gradually decrease as water saturation increases in the tank, but sharp drops occurred as individual fingers bridged the tank. The magnitude of this effect decreased as the displacement became increasingly unstable until a smooth transition occurred for highly unstable flows. By analyzing the dynamic data using Archie’s law, we found that the apparent saturation exponent increases linearly between approximately 1 and 2 as a function of generalized Bond number, after which it remained constant for unstable flows with a generalized Bond number less than −0.106.

Unstable Two-Fluid Flow in a Porous Medium

1969 ◽  
Vol 9 (03) ◽  
pp. 293-300 ◽  
Author(s):  
J.E. Varnon ◽  
R.A. Greenkorn
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Flow Regime ◽  
Flow Regimes ◽  
Gravity Force ◽  
Unstable Flow ◽  
Stable Regime ◽  
Viscous Forces ◽  
Finger Width ◽  
Two Fluid

Abstract This paper reports an investigation of unstable fingering in two-fluid flow in a porous medium to determine if lambda the dimensionless finger width, is unique For a viscous finger A is the ratio of finger width to the distance between the tips of the two trailing fingers adjacent to the leading finger. For a gravity finger lambda is defined as the ratio of finger width, to "height" of the medium perpendicular to hulk flow. This work confirms previous experiments and existing theory that for viscous fingering lambda approaches a value of 0.5 with increasing ratio of viscous to interfacial force. However, for a given fluid pair and given, medium, this ratio can he increased only by increasing the, velocity. Experiments on gas liquid systems show that the asymptotic value of lambda with velocity is not always 0.5. Apparently, for gas-liquid systems, the influence of the interfacial force cannot always he eliminated by increasing the velocity. For such systems lambda is a function of fluid pair and media permeability. If the gravity force normal to the hulk permeability. If the gravity force normal to the hulk flow is active, it damps out the viscous fingers except for an underlying or overlying finger. The dimensionless width of this gravity finger strongly depends on velocity and height of the medium, as well as the fluid and media properties. The existing experiments and theories are reviewed and the gravity, stable, and viscous flow regimes are described in view of these experiments and theories. The existence of a gravity-dominated unstable regime, a gravity-viscous balanced stable regime, and a viscous-anminated regime was demonstrated experimentally by increasing flow velocity bin a rectangular glass head model. Asymptotic values of the dimensionless finger width were determined in various-sized Hele-Shaw models with gravity perpendicular and parallel to flow. The dimensionless perpendicular and parallel to flow. The dimensionless finger width lambda was determined as a function of applied force, flow resistance, and fluid properties. The results are interpreted dimensionally. Some comments are made concerning possible scaling and meaningful extensions of theory to describe these regimes in three-dimensional flow. Previous description of unstable two-fluid flow in porous media is mainly restricted to studies of viscous-dominated instability. The direction of this study is to provide data and understanding to consider the more realistic problem of predicting flow in three dimensions that may result in instabilities that are combinations of all, four flow regimes. Introduction The unstable flow of two fluids is characterized by interface changes between the fluids as a result of changes in relative forces. In a given porous medium and for a given fluid pair the gravity force dominates flow at low displacement velocities. As the velocity increases the viscous forces begin to affect flow significantly, and eventually there is a balance between effects of the gravity and viscous forces. As velocity increases further, the viscous force dominates flow. In the plane parallel to gravity, four flow regimes result as the velocity is increased: a gravity-induced stable flow regime; a gravity-dominated unstable flow regime; a stable regime resulting from a balance between gravity and viscous forces; and a viscous-induced unstable flow regime. The gravity-induced stable regime is represented schematically in Fig. 1a. This general flow pattern persists with the displacing fluid contacting all of persists with the displacing fluid contacting all of the in-place fluid until the interface becomes parallel to the bulk flow. At this velocity a gravity finger forms, and the interface, is unstable in that the length of the gravity finger grows and the fluid behind the nose of the finger is practically nonmobile because of the small pressure gradient along the finger. The gravity-dominated unstable flow is shown schematically in Fig. 1b. As the injection rate is increased, the gravity finger thickens, perhaps until it spans the medium creating a stable interface where all of the in-place, fluid is again mobile. This regime would, not occur in the absence of gravity. It occurs due to the counter effects of the gravity and viscous forces (Fig. 1c). As the velocity of the displacing fluid increases, the viscous forces dominate, and, the interface breaks into viscous fingers (Fig. 1d). SPEJ p. 293

scholarly journals Quantitative Imaging and In Situ Concentration Measurements of Quantum Dot Nanomaterials in Variably Saturated Porous Media

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Burcu Uyuşur ◽  
Preston T. Snee ◽  
Chunyan Li ◽  
Christophe J. G. Darnault
Keyword(s):  
Porous Media ◽  
Quantum Dot ◽  
Light Transmission ◽  
Water Saturation ◽  
Uv Light ◽  
Light Exposure ◽  
Fluorescence Method ◽  
Fluorescent Light ◽  
Subsurface Environment

Knowledge of the fate and transport of nanoparticles in the subsurface environment is limited, as techniques to monitor and visualize the transport and distribution of nanoparticles in porous media and measure their in situ concentrations are lacking. To address these issues, we have developed a light transmission and fluorescence method to visualize and measure in situ concentrations of quantum dot (QD) nanoparticles in variably saturated environments. Calibration cells filled with sand as porous medium and various known water saturation levels and QD concentrations were prepared. By measuring the intensity of the light transmitted through porous media exposed to fluorescent light and by measuring the hue of the light emitted by the QDs under UV light exposure, we obtained simultaneously in situ measurements of water saturation and QD nanoparticle concentrations with high spatial and temporal resolutions. Water saturation was directly proportional to the light intensity. A linear relationship was observed between hue-intensity ratio values and QD concentrations for constant water saturation levels. The advantages and limitations of the light transmission and fluorescence method as well as its implications for visualizing and measuring in situ concentrations of QDs nanoparticles in the subsurface environment are discussed.

scholarly journals FENOMENA TRANSPORT KOBALT-60 PADA LAPISAN TANAH

2013 ◽  
Vol 3 (1) ◽  
pp. 21
Author(s):  
Ngasifudin .
Keyword(s):  
Transport Phenomenon ◽  
Manganese Oxide ◽  
Clay Minerals ◽  
Concentration Profile ◽  
Maximum Concentration ◽  
Soil Column ◽  
Extraction Methods ◽  
Soil Component ◽  
Soil Components ◽  
Column Extraction

The transport phenomena of cobalt-60 (Co-60) in the soillayer has been investigated using column and batch methods. The association of Co-60 with soil and its components were studied by extraction methods. The concentration profile of Co-60 in the soil column was composed of two logarithmic curves that showing Co-60 would be consist of mobile and immobile fraction. The immobile fraction of Co-60 was adsorbed by soil and was distributed near in the top of column. Although the mobile Co-60 was little sorbed by soil and migrated through the soil column, themaximum concentration of Co-60 in the effluents decreased slightly with increasing length of the soil column. Extraction of Co-60 from the soil and from its components showed that Co-60 was sorbed by manganese oxide and clay minerals. Manganese oxide is one of the soil components that could be decrease the maximum concentration of Co-60 in the effluents. Although the content of manganese oxide in the soil was 0.24-0.29%, manganese oxide is the important component to preventthe migration of Co-60 in the low acidic solution.Keywords : Transport phenomenon, Cobalt-60, soil component Telah dilakukan penelitian tentang fenomena gerakan Kobalt-60 (Co-60) pada lapisan tanah yang dilakukan secara kolom dan batch. Penggabungan Co-60.dengan tanah dan komponennya dipelajari dengan serangkaian teknik ekstraksi. Gambaran konsentrasi Co- 60 di dalam kolom tanah tersusun oleh dua kurva logaritma yang menunjukkan Co-60 terdiri atas fraksi gerak dan tidak-gerak. Fraksi Co-60 tidak-gerak diserap oleh tanah dan didistribusikan di dekat bagian atas kolom. Meskipun Co-60 fraksi gerak hanya sedikit terserap oleh tanah dan di-transportkan melalui kolom tanah, konsentrasi maksimum Co- 60 di dalam efluen sedikit menurun dengan kenaikan panjang kolom tanah. Ekstraksi Co-60 dari tanah dan komponennya menunjukkan bahwa Co-60 diserap oleh mangan dioksida dan komponen lempung. Mangan oksida merupakan salah satu komponen tanah yang dapat menurunkan konsentrasi maksimum Co-60 di dalam efluen. Bahkan kandungan mangan oksida 0,24-0,29% dalam tanah menjadi komponen penting untukmencegah proses transport Co-60 pada larutan keasaman rendah.Kata kunci : Fenomena transport, Kobalt-60, komponen tanah 

Soil Landscapes of Canada: Building a National Framework for Environmental Information

GEOMATICA ◽  
2011 ◽  
Vol 65 (3) ◽  
pp. 293-309 ◽  
Author(s):  
Peter Schut ◽  
Scott Smith ◽  
Walter Fraser ◽  
Xiaoyuan Geng ◽  
David Kroetsch
Keyword(s):  
Information Service ◽  
Spatial Modelling ◽  
Environmental Information ◽  
Parent Material ◽  
Climate Change Scenarios ◽  
Soil Component ◽  
Soil Components ◽  
Data Tables ◽  
Landscape Information ◽  
Agricultural Areas

The Soil Landscapes of Canada (SLC) is a national soil map and accompanying database of environmental information for all of Canada, produced and maintained by the Canadian Soil Information Service (CanSIS) which is a part of Agriculture and Agri-Food Canada. The SLC maps were originally published as a set of paper products for individual provinces and regions. The maps were digitized in CanSIS, using one of the first geographic information systems in the world, and linked to soil and landscape attribute tables to serve an evolving variety of spatial modelling applications. The SLCs form the lowest level of the National Ecological Framework for Canada. The latest public release of the SLC is version 3.2, which provides updated soil and landscape information for the agricultural areas of Canada. The SLC v3.2 digital coverage includes an extensive set of relational data tables. The component table lists the soil components in each agricultural polygon along with their predicted dominant slope, class, and extent. The soil component codes are also linked to soil attribute tables which define fundamental soil properties, such as classification and parent material, as well as a description of the soil horizons and key soil attributes to a depth of 100 cm. SLC v3.2 adds a new set of landform tables which identify the major landform type in each polygon and indicates the most likely soil components in the upper, mid slope, lower slope, and depressional positions. These soil and landform attributes are designed to support a wide variety of national and international environmental modelling applications, such as the prediction of soil quality change, soil carbon sequestration, and land productivity for different agricultural crops in response to agricultural policy, land management, and climate change scenarios. Future versions of the SLC are under development that will have improved spatial resolution and include soils data for areas beyond the present agricultural zone of Canada.

scholarly journals Chloride Transport in Undersea Concrete Tunnel

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yuanzhu Zhang ◽  
Xiaozhen Li ◽  
Guohua Yu
Keyword(s):  
Water Saturation ◽  
Chloride Transport ◽  
Water Pressure ◽  
Chloride Concentration ◽  
Solution Concentration ◽  
Chloride Diffusion ◽  
Hydraulic Pressure ◽  
Chloride Diffusion Coefficient ◽  
External Water Pressure ◽  
External Water

Based on water penetration in unsaturated concrete of underwater tunnel, a diffusion-advection theoretical model of chloride in undersea concrete tunnel was proposed. The basic parameters including porosity, saturated hydraulic conductivity, chloride diffusion coefficient, initial water saturation, and moisture retention function of concrete specimens with two water-binder ratios were determined through lab-scale experiments. The variation of chloride concentration with pressuring time, location, solution concentration, initial saturation, hydraulic pressure, and water-binder ratio was investigated through chloride transport tests under external water pressure. In addition, the change and distribution of chloride concentration of isothermal horizontal flow were numerically analyzed using TOUGH2 software. The results show that chloride transport in unsaturated concrete under external water pressure is a combined effect of diffusion and advection instead of diffusion. Chloride concentration increased with increasing solution concentration for diffusion and increased with an increase in water pressure and a decrease in initial saturation for advection. The dominant driving force converted with time and saturation. When predicting the service life of undersea concrete tunnel, it is suggested that advection is taken into consideration; otherwise the durability tends to be unsafe.

Sign in / Sign up

Export Citation Format

Share Document