Light Liquids Research Articles

Assessment of LNAPL in Subsurface under Fluctuating Groundwater Table Using 2D Sand Tank Experiments

AbstractThe focus of this study was to investigate the fate and transport of toluene, a light nonaqueous-phase liquids (LNAPLs) in the subsurface region under dynamic groundwater table conditions. ...

Particle-based Simulation of Rayleigh-Taylor Instability

Rayleigh-Taylor instability is a typical benchmark in a computational fluid dynamics, which show interpenetrate materials happened when a heavy liquid is above a lighter liquid. In particle method, Shirakawa et. al. had been proposed a correction term on modelling a buoyancy force to show the phenomena of Rayleigh-Taylor instability (RTI) in the simulation. By adjust a specific value of correction term for a specific mass density ratio, Rayleigh-Taylor instability phenomena had been observed on MPS method. Later, the phenomena is also observed on FVP methods using the same modelling. In this study, several mass density ratio and viscosity ratio of liquids have been proposed as parametric simulation to observe Rayleigh-Taylor instability. The results show the correlations between mass density ratio and viscosity ratio in the specific correction term value of buoyancy model. This results confirmed that the RTI phenomena can be observed in specific mass density ratio.

Preferential positioning and phase exposure of granular particles at hydrophobic liquid-water interface

The positioning of granular limestone and quartz particles at the hydrophobic liquid-water interfaces was evaluated and compared experimentally and analyzed by the theoretical analyses by considering the electrostatic interaction and gravitational effects. Experiments were performed with light hydrophobic liquids (tetradecane, silicone oil with viscosities 10 and 100 cSt, and South Louisiana crude oil) which were submerged by granular limestone and quartz with different particle sizes (average particle radius 0.25, 0.10, <0.004 mm). The particles of similar size but different materials (i.e., limestone, quartz) exhibited noticeably different behavior within the hydrophobic phase and in their positioning and transport towards the hydrophobic liquid-water interface. The comparison of the dimensionless Bond number for the systems evaluated showed discrepancies between the Bond number theory and experimental observations. The preferential behavior of less than millimeter sized granular particles at the hydrophobic liquid-water interface was found to be predominantly affected by the electrostatic force only.

Flotation of Denser Liquid Drops on Lighter Liquids in Non-Neumann Condition: Role of Line Tension.

Flotation of a denser liquid drop on lighter liquid has been explained earlier via the Neumann triangle. We demonstrate the flotation of a denser liquid (water) drop on a lighter liquid in a pair that does not satisfy the Neumann triangle. We attribute this newly studied phenomenon to the role of line tension τ which prevents the water droplet from complete engulfment. A simple model is used to explain the underlying physics and to obtain critical line tension value for stable flotation. We establish line tension values for different liquids with water and show possible heterogeneous nucleation that contributes toward the variance of line tension values.

Detection of non-aqueous phase liquid contamination by SH-TE seismoelectrics: A computational feasibility study

In this work we propose a one dimensional numerical study of the seismoelectric signals produced in a fresh water aquifer contaminated by either light or dense non-aqueous phase liquids ((L/D)NAPLs), considering a pure SH-wave seismic source. We investigate the nature of the electromagnetic response generated at media interfaces, the so called Interface Response (IR), by comparing it with the electromagnetic field generated by a current sheet; wherefrom we are able to interpret that the source of the IR behaves as an electric current flowing along the interface, differently to what happens when the IR is originated by the action of a P-wave, where electric charge accumulation generates an electric dipole. We perform a parametric study to analyze how the presence of contaminants affects the IR, resorting to an effective media approach to compute mechanical and electromagnetic properties, and considering three different effective fluid-saturation dependent electrokinetic coupling coefficient models. We observe, as expected, that porosity plays an important role in the amplitude of the IRs. When considering different NAPL saturations, significant effects on the IRs are only seen when the thickness of the contaminated layer is above a threshold value, which depends on the present contaminant and the considered effective electrokinetic coupling coefficient model.

Quantitative assessment of radiation force effect at the dielectric air-liquid interface.

We induce nanometer-scale surface deformation by exploiting momentum conservation of the interaction between laser light and dielectric liquids. The effect of radiation force at the air-liquid interface is quantitatively assessed for fluids with different density, viscosity and surface tension. The imparted pressure on the liquids by continuous or pulsed laser light excitation is fully described by the Helmholtz electromagnetic force density.

Use of chemical fingerprint data to enhance remedial site investigations at petroleum impacted sites

ABSTRACTAs well known by remediation practitioners, the indispensable “road map” for remedial site investigation is the conceptual site model (CSM), in which contaminant sources and migration pathways are two of the most critical CSM components. The ultimate goal of site investigation is to delineate the extent of contaminants, which is constrained by migration pathways. As contaminant sources are the starting points of the migration pathways, understanding contaminant sources is critically important in developing and refining a CSM. In the world of liability dispute and litigation, identification of sources of petroleum hydrocarbons is one of the, if not the only, objectives. A variety of environmental forensic techniques have been developed over a long history of litigation and the validity of these techniques has been established through publication in peer-reviewed scientific journals and books, as well as the vigorous scrutiny of the litigation process. Among the techniques, chemical fingerprinting is arguably the earliest developed and the most widely used technique for petroleum hydrocarbon forensics. During remedial investigations at complex petroleum impacted sites, chemical fingerprint data are equally of value for source identification, which in turn helps in development and/or enhancement of CSMs. This article presents an overview of applications of chemical fingerprinting in remedial site investigation at petroleum hydrocarbon-impacted sites. The first scenario is about avoiding unnecessary site investigations through proving nonexistence of perceived or suspected contaminant sources. The second scenario is about mapping out light nonaqueous-phase liquids (LNAPL) migration pathways using petroleum biomarkers. The third scenario is about expediting cleanup by differentiating current from historical releases using GC/FID chromatograms. The final scenario is about application of chemical fingerprinting in natural source-zone depletion evaluation. Common to all the applications is that there is no involvement of other potential responsible parties. The chemical fingerprinting techniques were used to achieve the goals of remedial investigations through effective site characterization. In all scenarios, the effective site characterization helped to avoid unnecessary remedial investigation and/or to realize considerable cost savings when remediation is implemented.

Linear stability of a horizontal phase boundary subjected to shear motion

We investigate the stability of slowly smearing phase boundary that appears at the contact of two miscible liquids. A hydrodynamic flow is imposed along the boundary. The aim is to find out whether the slow diffusive smearing of a boundary can be overrun by faster mixing. The phase-field approach is used to model the evolution of the binary mixture. The linear stability in respect to 2D perturbations is studied. If the heavier liquid lies above the lighter liquid, the interface is unconditionally unstable due to the Rayleigh-Taylor and Kelvin-Helmholtz instabilities. The imposed flow accelerates the growth of the long-wave modes and suppresses the growth of the short-wave perturbations. Viscosity, diffusivity and capillarity reduce the growth of perturbations. If the heavier liquid underlies the lighter one, the interface can be stable. The stability boundaries are defined by the strength of gravity (density contrast) and the intensity of the imposed flow. Thinner interfaces are usually characterised by larger zones of instability. The thermodynamic instability, identified for the thicker interfaces with the thicknesses greater than the thickness of a thermodynamically equilibrium phase boundary, makes such interfaces unconditionally unstable. The zones of instability are enlarged by diffusive and capillary terms. Viscosity plays its stabilising role.

Modelling in-situ upgrading of heavy oil using operator splitting method

The in-situ upgrading (ISU) of bitumen and oil shale is a very challenging process to model numerically because of the large number of components that need to be modelled using a system of equations that are both highly non-linear and strongly coupled. Operator splitting methods are one way of potentially improving computational performance. Each numerical operator in a process is modelled separately, allowing the best solution method to be used for the given numerical operator. A significant drawback to the approach is that decoupling the governing equations introduces an additional source of numerical error, known as the splitting error. The best splitting method for modelling a given process minimises the splitting error whilst improving computational performance compared to a fully implicit approach. Although operator splitting has been widely used for the modelling of reactive-transport problems, it has not yet been applied to the modelling of ISU. One reason is that it is not clear which operator splitting technique to use. Numerous such techniques are described in the literature and each leads to a different splitting error. While this error has been extensively analysed for linear operators for a wide range of methods, the results cannot be extended to general non-linear systems. It is therefore not clear which of these techniques is most appropriate for the modelling of ISU. In this paper, we investigate the application of various operator splitting techniques to the modelling of the ISU of bitumen and oil shale. The techniques were tested on a simplified model of the physical system in which a solid or heavy liquid component is decomposed by pyrolysis into lighter liquid and gas components. The operator splitting techniques examined include the sequential split operator (SSO), the Strang-Marchuk split operator (SMSO) and the iterative split operator (ISO). They were evaluated on various test cases by considering the evolution of the discretization error as a function of the time-step size compared with the results obtained from a fully implicit simulation. We observed that the error was least for a splitting scheme where the thermal conduction was performed first, followed by the chemical reaction step and finally the heat and mass convection operator (SSO-CKA). This method was then applied to a more realistic model of the ISU of bitumen with multiple components, and we were able to obtain a speed-up of between 3 and 5.

Current perspectives on unconventional shale gas extraction in the Appalachian Basin

The Appalachian Basin is home to three major shales, the Upper Devonian, Marcellus, and Utica. Together, they contain significant quantities of tight oil, gas, and mixed hydrocarbons. The Marcellus alone is estimated to contain upwards of 500 trillion cubic feet of natural gas. The extraction of these deposits is facilitated by a combination of horizontal drilling and slick water stimulation (e.g., hydraulic fracturing) or “fracking.” The process of fracking requires large volumes of water, proppant, and chemicals as well as a large well pad (3–7 acres) and an extensive network of gathering and transmission pipelines. Drilling can generate about 1,000 tons of drill cuttings depending on the depth of the formation and the length of the horizontal bore. The flowback and produced waters that return to the surface during production are high in total dissolved solids (TDS, 60,000–350,000 mg L−1) and contain halides (e.g., chloride, bromide, fluoride), strontium, barium, and often naturally occurring radioactive materials (NORMs) as well as organics. The condensate tanks used to store these fluids can off gas a plethora of volatile organic compounds. The waste water, with its high TDS may be recycled, treated, or disposed of through deep well injection. Where allowed, open impoundments used for recycling are a source of air borne contamination as they are often aerated. The gas may be “dry” (mostly methane) or “wet,” the latter containing a mixture of light hydrocarbons and liquids that need to be separated from the methane. Although the wells can produce significant quantities of natural gas, from 2–7 bcf, their initial decline rates are significant (50–75%) and may cease to be economic within a few years. This review presents an overview of unconventional gas extraction highlighting the environmental impacts and challenges.

An improved viscosity model based on Peng–Robinson equation of state for light hydrocarbon liquids and gases

Recently, a PRμ viscosity model was developed by Fan et al. It is applicable to both the liquid and gas hydrocarbons, but some large deviations might be obtained when applied to some multi-component mixtures. This short communication proposes an improvement method to enhance the accuracy of this model. The method replaces the universal critical compressibility factor in the original model with each component's real critical compressibility factor. The experimental viscosity data of pure methane, pure propane and thirteen light liquid hydrocarbon mixtures were adopted to validate the improved model. The results show the improved model is suitable to both the light hydrocarbon liquids and gases with satisfactory accuracy. The average ARD of the PRμ model was enhanced 4.78% when applied to thirteen hydrocarbon mixtures. Additionally, when applied to five complicated Qatari synthetic natural gas mixtures, the improved PRμ model is essentially comparable in predictability to five other viscosity prediction models.

Resistance of Polymer Dispersion Additive Modified Concrete to Light Liquids Action

Numerous concrete and reinforced concrete structures (industrial floors, petrol station or manoeuvring park pavements, elements of sewage system) are subjected to danger of permanent or periodical action of petroleum liquids that often causes the considerable reduction in concrete strength as well as decrease of bond between concrete and steel, which usually results in structure damages. The subject of the paper is estimation of influence of polymer dispersion additive (styrene-acrylic co-polymer and styrene-butadiene latex) onto durability of concrete subjected to action of different types of light liquids. The influence of polymer dispersion additive was confronted with the action of silica fume usually applied for sealing the structure of concrete. In the paper there are presented tests results for different types of light liquids onto such cement-polymer concrete properties as: strength, penetration depth of light liquids into material structure.

Effects of thermal aging on mechanical properties of laminated lead and natural rubber bearing

Laminated rubber bearing is very popular base isolation of earthquake engineering pertaining to the passive structural vibration control technologies. Rubber used in fabricating NRB and LRB can be easily attacked by various environmental factors such as oxygen, heat, light, dynamic strain, and organic liquids. Among these factors, this study carried out thermal aging test to investigate the effect of thermal aging on the mechanical properties of laminated rubber bearings in accelerated exposure condition of <TEX>$70^{\circ}C$</TEX> temperature for 168 hours. The compressive-shear test was carried out to identify the variation of compressive and shear properties of the rubber bearings before and after thermal aging. In contrast to tensile strength and elongation tests, the hardness of rubber materials showed the increasing tendency dependent on exposure temperature and period. Based on the test results, the property changes of rubber bearing mainly aged by heat are quantitatively presented.

An arbitrary Lagrangian Eulerian method for three-phase flows with triple junction points

We present a moving mesh method suitable for solving two-dimensional and axisymmetric three-liquid flows with triple junction points. This method employs a body-fitted unstructured mesh where the interfaces between liquids are lines of the mesh system, and the triple junction points (if exist) are mesh nodes. To enhance the accuracy and the efficiency of the method, the mesh is constantly adapted to the evolution of the interfaces by refining and coarsening the mesh locally; dynamic boundary conditions on interfaces, in particular the triple points, are therefore incorporated naturally and accurately in a finite-element formulation. In order to allow pressure discontinuity across interfaces, double-values of pressure are necessary for interface nodes and triple-values of pressure on triple junction points. The resulting non-linear system of mass and momentum conservation is then solved by an Uzawa method, with the zero resultant condition on triple points reinforced at each time step. The method is used to investigate the rising of a liquid drop with an attached bubble in a lighter liquid.

Acoustic Conductance of an Anisotropic Shell Submerged in a Liquid 2. A Parametric Analysis of Frequency Characteristics1

Based on a model of radial vibrations of a hollow sphere caused by a harmonic source located on its inner radius, the frequency spectrum of a spherical shell, made of a transversely isotropic material and contacting a liquid medium, under changes in its thickness and in material properties in the circumferential and radial directions is investigated. The eigenvalues of the boundary-value problem are considered in an arbitrary range of physical parameters of the model by using functions of complex variable and the theory of residues. The solution of the transcendental equation for eigenvalues (frequencies), which is obtained as a combination of modified Bessel functions, is analyzed in the cases of light and heavy incompressible liquids (or vacuum). The values of eigenfrequencies are presented and analyzed with respect to depth of the region of disturbance (or thickness of the shell) and material properties. The approximate values of thickness of the anisotropic sphere corresponding to a steep rise in the natural frequencies of radial vibrations are revealed. The wave model of a thick-wall sphere is transformed into the vibration analog of a thin-wall shell.

Synthesis, Spectroscopic Studies and Antifungal Activity of O-Alkyl or O-Aryl Trithiophosphate Derivatives of Trimethylaminoborane

In this work, we report on the synthesis, characterization, and antifungal activities of new boron derivatives of O-alkyl or O-aryl trithiophosphate of the type ROP(S)S2[BS2P(S)OR]2·2NMe3 (R = Me, Et, Pri, Bui, Ph, CH2Ph). They were synthesized by the reaction of trimethylaminoborane with O-alkyl or O-aryl trithiophosphate in 2:3 molar ratio in dried and distilled benzene. The newly synthesized derivatives are light yellow viscous liquids, monomer, and soluble in common organic solvents. These compounds have been characterized by elemental analysis, molecular weight determinations, and spectroscopic (IR, 1H, 11B, and 31P NMR) studies which are consistent with four-coordinated boron and bidentate behavior of the trithiophosphate moiety. It is observed that when these derivatives are applied in the form of dilute solution in ethanol of various concentrations, they show their effectiveness against powdery mildew disease at a fixed interval of days. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Blending of miscible liquids with different densities starting from a stratified state

Homogenization of initially segregated and stably stratified systems consisting of two miscible liquids with different density and the same kinematic viscosity in an agitated tank was studied computationally. Reynolds numbers were in the range of 3000–12,000 so that it was possible to solve the flow equations without explicitly modeling turbulence. The Richardson number that characterizes buoyancy was varied between 0 and 1. The stratification clearly lengthens the homogenization process. Two flow regimes could be identified. At low Richardson numbers large, three-dimensional flow structures dominate mixing, as is the case in non-buoyant systems. At high Richardson numbers the interface between the two liquids largely stays intact. It rises due to turbulent erosion, gradually drawing down and mixing up the lighter liquid.

Designing PLANET: Neutron beamline for high-pressure material science at J-PARC

The powder diffractometer dedicated to high-pressure experiments (PLANET) is now being constructed on BL11 at the spallation neutron source of J-PARC. PLANET aims to study structures of hydrogen-bearing materials including dense hydrous minerals of the Earth's deep interior, magmas and light element liquids. The instrument will realize diffraction and radiography experiments for powder and liquid/glass samples at high pressures up to 20 GPa and 2000 K. It covers d spacing from 0.2 Å to 4.1 Å at 90° bank within the first frame. The design and performance of PLANET have been evaluated using Monte Carlo simulations.

Experimental and numerical study of miscible Faraday instability

A study of the Faraday instability of diffuse interfaces between pairs of miscible liquids of different densities, by means of experiments and by a nonlinear numerical model, is presented. The experimental set-up consisted of a rectangular cell in which the lighter liquid was placed above the denser one. The cell in this initially stable configuration was then subjected to vertical vibrations. The subsequent behaviour of the ‘interface’ between the two liquids was observed with a high-speed camera. This study shows that above a certain acceleration threshold an instability developed at the interface. The amplitude of the instability grew during the experiments which then led to the mixing of the liquids. The instability finally disappeared once the two liquids were fully mixed over a volume, considerably larger than the initial diffuse region. The results of a companion two-dimensional nonlinear numerical model that employs a finite volume method show very good agreement with the experiments. A physical explanation of the instability and the observations are advanced.

Liquid Taylor Bubbles Rising in a Vertical Column of a Heavier Liquid: An Approximate Analysis

It has been noted that a volume of lighter liquid when injected into a stationary column of a heavier liquid, it rises up as a simple elongated Taylor bubble. In the present study, experimental and theoretical analyses have been performed to understand the rise of liquid Taylor bubbles. The experiments have been performed with different liquid pairs with their viscosities ranging from 0.71mPas to 1.75mPas and conduit sizes ranging from 0.012 m to 0.0461 m. The bubble shape has been predicted using a potential flow analysis and validated from photographic measurements. This analysis has been further modified to predict the rise velocity. The modified analysis accounts for the density difference between the two liquids, viscosity effects of the primary liquid, and interfacial tension of two fluids. A semi-empirical equation has been developed, which gives satisfactory results for most of the cases.