scholarly journals Streamline-Based Simulation of Nanoparticle Transport in Field-Scale Heterogeneous Subsurface Systems

2020 ◽  
Author(s):  
Bin Wang ◽  
Yin Feng ◽  
John Blears ◽  
Karsten Thompson ◽  
Richard Hughes
Keyword(s):  
Environmental Remediation ◽  
Transport Model ◽  
Operator Splitting ◽  
Heterogeneous Systems ◽  
Entire Solution ◽  
Breakthrough Curves ◽  
Engineered Nanoparticles ◽  
Field Scale ◽  
Diffusion Term ◽  
Advection Term

Nanoparticle (NP) transport is increasingly relevant to subsurface engineering applications such as aquifer characterization, fracture electromagnetic imaging and environmental remediation. An efficient field-scale simulation framework is critical for predicting NP performance and designing subsurface applications. In this work, for the first time, a streamline-based model is presented to simulate NP transport in field-scale subsurface systems. It considers a series of behaviors exhibited by engineered nanoparticles (NPs), including time-triggered encapsulation, retention, formation damage effects and variable nanofluid viscosity. The key methods employed by the algorithm are streamline-based simulation (SLS) and an operator-splitting (OS) technique for modeling NP transport. SLS has proven to be efficient for solving transport in large and heterogeneous systems, where the pressure and velocity fields are firstly solved on underlying grids using finite-difference (FD) methods. After tracing streamlines, one-dimensional (1D) NP transport is solved independently along each streamline. The adoption of OS enhances flexibility for the entire solution procedure by allowing different numerical schemes to solve different governing equations efficiently and accurately. For the NP transport model, an explicit FD scheme is used to solve the advection term, an implicit FD scheme is used for the diffusion term and an adaptive numerical integration is used to solve the retention terms. The model is implemented in an in-house streamline-based code, which is verified against analytical solutions, a commercial FD reservoir simulator (ECLIPSE) and an academic FD colloid transport code (MNMs). For a 1D homogeneous case, the effluent breakthrough curves (BTC) produced by the in-house simulator are in good agreement with the analytical solution and MNMs, respectively. For a two-dimensional (2D) heterogeneous case, the BTC and concentration pattern of the in-house simulator all match well with the solution produced by commercial simulator. Simulations on a synthetic three-dimensional (3D) nanocapsule application engineering design case, are performed to investigate the effect of fluid and NP properties on the displacement pattern of an existing subsurface fluid.

scholarly journals The impact of nanoparticle aggregation on their size exclusion during transport in porous media: One- and three-dimensional modelling investigations

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Peyman Babakhani
Keyword(s):  
Porous Media ◽  
Transport Model ◽  
Three Dimensional ◽  
Breakthrough Curves ◽  
Engineered Nanoparticles ◽  
Acceleration Factor ◽  
Size Exclusion ◽  
Residual Concentration ◽  
Injection Point ◽  
The Impact

Abstract Greater particle mobility in subsurface environments due to larger size, known as size exclusion, has been responsible for colloid-facilitated transport of groundwater contaminants. Although size exclusion is not expected for primary engineered nanoparticles (NP), they can grow in size due to aggregation, thereby undergoing size exclusion. To investigate this hypothesis, an accurate population balance modelling approach and other colloid transport theories, have been incorporated into a three-dimensional transport model, MT3D-USGS. Results show that incorporating aggregation into the transport model improves the predictivity of current theoretical and empirical approaches to NP deposition in porous media. Considering an artificial size-variable acceleration factor in the model, NP breakthrough curves display an earlier arrival when aggregation is included than without. Disregarding the acceleration factor, aggregation enhances NP mobility at regions close to the injection point at a field scale and causes their retention at greater distances through alteration of their diffusivities, secondary interaction-energy minima, and settling behaviour. This results in a change of residual concentration profiles from exponential for non-aggregating dispersions to non-monotonic for aggregating dispersions. Overall, aggregation, hitherto believed to hinder the migration of NP in subsurface porous media, may under certain physicochemical conditions enhance their mobilities and deliver them to further distances.

REVIEW ON RECENT ADVANCES IN ENVIRONMENTAL REMEDIATION AND RELATED TOXICITY OF ENGINEERED NANOPARTICLES

2016 ◽  
Vol 15 (4) ◽  
pp. 923-934 ◽  
Author(s):  
Mohammadreza Kamali ◽  
Ana Paula Duarte Gomes ◽  
Zahra Khodaparast ◽  
Tahereh Seifi
Keyword(s):  
Environmental Remediation ◽  
Engineered Nanoparticles ◽  
Recent Advances

Parameter Determination for Chloride and Tritium Transport in Undisturbed Lysimeters during Steady Flow

1992 ◽  
Vol 23 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Ole H. Jacobsen ◽  
Feike J. Leij ◽  
Martinus Th. van Genuchten
Keyword(s):  
Experimental Data ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Time Moment ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Retardation Factor ◽  
Parameter Determination ◽  
Model Parameters ◽  
Water Fraction

Breakthrough curves of Cl and 3H2O were obtained during steady unsaturated flow in five lysimeters containing an undisturbed coarse sand (Orthic Haplohumod). The experimental data were analyzed in terms of the classical two-parameter convection-dispersion equation and a four-parameter two-region type physical nonequilibrium solute transport model. Model parameters were obtained by both curve fitting and time moment analysis. The four-parameter model provided a much better fit to the data for three soil columns, but performed only slightly better for the two remaining columns. The retardation factor for Cl was about 10 % less than for 3H2O, indicating some anion exclusion. For the four-parameter model the average immobile water fraction was 0.14 and the Peclet numbers of the mobile region varied between 50 and 200. Time moments analysis proved to be a useful tool for quantifying the break through curve (BTC) although the moments were found to be sensitive to experimental scattering in the measured data at larger times. Also, fitted parameters described the experimental data better than moment generated parameter values.

scholarly journals MHDSTS: a new explicit numerical scheme for simulations of partially ionised solar plasma

2018 ◽  
Vol 615 ◽  
pp. A67 ◽  
Author(s):  
P. A. González-Morales ◽  
E. Khomenko ◽  
T. P. Downes ◽  
A. de Vicente
Keyword(s):  
Numerical Scheme ◽  
Operator Splitting ◽  
Conservation Equation ◽  
Ambipolar Diffusion ◽  
Point Of View ◽  
Integration Time ◽  
Solar Photosphere ◽  
Time Step ◽  
Diffusion Term ◽  
Fluid Approximation

The interaction of plasma with magnetic field in the partially ionised solar atmosphere is frequently modelled via a single-fluid approximation, which is valid for the case of a strongly coupled collisional media, such as solar photosphere and low chromosphere. Under the single-fluid formalism the main non-ideal effects are described by a series of extra terms in the generalised induction equation and in the energy conservation equation. These effects are: Ohmic diffusion, ambipolar diffusion, the Hall effect, and the Biermann battery effect. From the point of view of the numerical solution of the single-fluid equations, when ambipolar diffusion or Hall effects dominate can introduce severe restrictions on the integration time step and can compromise the stability of the numerical scheme. In this paper we introduce two numerical schemes to overcome those limitations. The first of them is known as super time-stepping (STS) and it is designed to overcome the limitations imposed when the ambipolar diffusion term is dominant. The second scheme is called the Hall diffusion scheme (HDS) and it is used when the Hall term becomes dominant. These two numerical techniques can be used together by applying Strang operator splitting. This paper describes the implementation of the STS and HDS schemes in the single-fluid code MANCHA3D. The validation for each of these schemes is provided by comparing the analytical solution with the numerical one for a suite of numerical tests.

Advances in understanding the transformation of engineered nanoparticles in the environment

2014 ◽  
Vol 86 (7) ◽  
pp. 1129-1140 ◽  
Author(s):  
Setare Tahmasebi Nick ◽  
Ali Bolandi ◽  
Tova A. Samuels ◽  
Sherine O. Obare
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Physical Properties ◽  
Recent Work ◽  
Environmental Remediation ◽  
Health And Safety ◽  
Green Manufacturing ◽  
Consumer Products ◽  
Engineered Nanoparticles ◽  
Proactive Study

AbstractEngineered nanoparticles (ENPs) are known to possess unique size and shape dependent chemical and physical properties. As a result of their properties, ENPs have been effective in several important applications including catalysis, sensor design, photonics, electronics, medicine, and the environmental remediation of toxic pollutants. Such properties and applications have led to an increase in the manufacture of ENPs and a rise in their presence in consumer products. The increase of ENPs in consumer products presents several opportunities and challenges, and necessitates a proactive study of their health and safety. This article highlights some recent work in which we have studied the effect of exposure of well-defined ENPs to pesticides and the effect of pH and dissolved organic matter. We also summarize our work and that of others who have studied the toxicity of ENPs with microorganisms. The results provide insights on the need for green manufacturing strategies of ENPs, their use and safe disposal practices.

scholarly journals Stochastic modelling and diffusion modes for proper orthogonal decomposition models and small-scale flow analysis

2017 ◽  
Vol 826 ◽  
pp. 888-917 ◽  
Author(s):  
Valentin Resseguier ◽  
Etienne Mémin ◽  
Dominique Heitz ◽  
Bertrand Chapron
Keyword(s):  
Fluid Flow ◽  
Velocity Component ◽  
Large Scale ◽  
Stochastic Modelling ◽  
Wake Flow ◽  
Small Scale ◽  
Cylinder Wake ◽  
Diffusion Term ◽  
Advection Term ◽  
Dimensional Models

We present here a new stochastic modelling approach in the constitution of fluid flow reduced-order models. This framework introduces a spatially inhomogeneous random field to represent the unresolved small-scale velocity component. Such a decomposition of the velocity in terms of a smooth large-scale velocity component and a rough, highly oscillating component gives rise, without any supplementary assumption, to a large-scale flow dynamics that includes a modified advection term together with an inhomogeneous diffusion term. Both of those terms, related respectively to turbophoresis and mixing effects, depend on the variance of the unresolved small-scale velocity component. They bring an explicit subgrid term to the reduced system which enables us to take into account the action of the truncated modes. Besides, a decomposition of the variance tensor in terms of diffusion modes provides a meaningful statistical representation of the stationary or non-stationary structuration of the small-scale velocity and of its action on the resolved modes. This supplies a useful tool for turbulent fluid flow data analysis. We apply this methodology to circular cylinder wake flow at Reynolds numbers $Re=100$ and $Re=3900$. The finite-dimensional models of the wake flows reveal the energy and the anisotropy distributions of the small-scale diffusion modes. These distributions identify critical regions where corrective advection effects, as well as structured energy dissipation effects, take place. In providing rigorously derived subgrid terms, the proposed approach yields accurate and robust temporal reconstruction of the low-dimensional models.

Investigation of Underground Bio-Methanation Using Bio-Reactive Transport Modeling

2021 ◽  
Author(s):  
Denis Sergeevich Nikolaev ◽  
Nazika Moeininia ◽  
Holger Ott ◽  
Hagen Bueltemeier
Keyword(s):  
Carbon Dioxide ◽  
Reactive Transport ◽  
Transport Model ◽  
Porous Media Flow ◽  
Potential Candidate ◽  
Field Scale ◽  
Reactive Transport Model ◽  
Demand Fluctuations ◽  
Gas Fields ◽  
The Impact

Abstract Underground bio-methanation is a promising technology for large-scale renewable energy storage. Additionally, it enables the recycling of CO2 via the generation of "renewable methane" in porous reservoirs using in-situ microbes as bio-catalysts. Potential candidate reservoirs are depleted gas fields or even abandoned gas storages, providing enormous storage capacity to balance seasonal energy supply and demand fluctuations. This paper discusses the underlying bio-methanation process as part of the ongoing research project "Bio-UGS – Biological conversion of carbon dioxide and hydrogen to methane," funded by the German Federal Ministry of Education and Research (BMBF). First, the hydrodynamic processes are assessed, and a review of the related microbial processes is provided. Then, based on exemplary field-scale simulations, the bio-reactive transport process and its consequences for operation are evaluated. The hydrogen conversion process was investigated by numerical simulations on field scale. For this, a two-phase multi-component bio-reactive transport model was implemented by (Hagemann 2018) in the open-source DuMux (Flemisch et al. 2011) simulation toolkit for porous media flow. The underlying processes include the transport of reactants and products, consumption of specific components, and the related growth and decay of the microbial population, resulting in a bio-reactive transport model. The microbial kinetic parameters of methanogenic reactions are taken from the available literature. The simulation study covers different scenarios on conceptional field-scale models, studying the impact of well placement, injection rates, and gas compositions. Due to a significant sensitivity of the simulation results to the bio-conversion kinetics, the field-specific conversion rates must be obtained. Thus, the Bio-UGS project is accompanied by laboratory experiments out of the frame of this paper. Other parameters are rather a matter of design; in the present case of depleted gas fields, those parameters are coupled and can be chosen to convert fully hydrogen and carbon dioxide to methane. Especially the well spacing can be considered the main design parameter in the likely case of a given injection rate and gas composition. This study extends the application of the previously developed code from a homogeneous-2D to the heterogeneous-3D case. The simulations mimic the co-injection of carbon dioxide and hydrogen from a 40 MW electrolysis.

scholarly journals Comparison of three stream tube models predicting field-scale solute transport

1997 ◽  
Vol 1 (4) ◽  
pp. 873-893 ◽  
Author(s):  
D. Jacques ◽  
J. Vanderborght ◽  
D. Mallants ◽  
D.-J. Kim ◽  
H. Vereecken ◽  
...  
Keyword(s):  
Solute Transport ◽  
Transport Model ◽  
Local Scale ◽  
Transfer Model ◽  
Transport Parameters ◽  
Field Scale ◽  
Stream Tube ◽  
Solute Dispersion ◽  
Measurement Volume ◽  
Piston Flow

Abstract. In this paper the relation between local- and field-scale solute transport parameters in an unsaturated soil profile is investigated. At two experimental sites, local-scale steady-state solute transport was measured in-situ using 120 horizontally installed TDR probes at 5 depths. Local-scale solute transport parameters determined from BTCs were used to predict field-scale solute transport using stochastic stream tube models (STM). Local-scale solute transport was described by two transport models: (1) the convection-dispersion transport model (CDE), and (2) the stochastic convective lognormat transfer model (CLT). The parameters of the CDE-model were found to be lognormally distributed, whereas the parameters of the CLT model were normally distributed. Local-scale solute transport heterogeneity within the measurement volume of a TDR-probe was an important factor causing field-scale solute dispersion. The study of the horizontal scale-dependency revealed that the variability in the solute transport parameters contributes more to the field-scale dispersion at deeper depths than at depths near the surface. Three STMs were used to upscale the local transport parameters: (i) the stochastic piston flow STM-I assuming local piston flow transport, (ii) the convective-dispersive STM-II assuming local CDE transport, and (iii) the stochastic convective lognormal STM-III assuming local CLT. The STM-I considerably underpredicted the field-scale solute dispersion indicating that local-scale dispersion processes, which are captured within the measurement volume of the TDR-probe, are important to predict field-scale solute transport. STM-II and STM-III both described the field-scale breakthrough curves (BTC) accurately if depth dependent parameters were used. In addition, a reasonable description of the horizontal variance of the local BTCs was found. STM-III was (more) superior to STM-II if only one set of parameters from one depth is used to predict the field-scale solute BTCs at several depths. This indicates that the local-scale solute transport process, as measured with TDR in this study, is in agreement with the CLT-hypothesis.

scholarly journals Stochastic analysis of field-scale heat advection in heterogeneous aquifers

2012 ◽  
Vol 16 (3) ◽  
pp. 641-648 ◽  
Author(s):  
C.-M. Chang ◽  
H.-D. Yeh
Keyword(s):  
Temperature Field ◽  
Heat Transport ◽  
Stochastic Analysis ◽  
Transport Model ◽  
Field Scale ◽  
Heat Advection ◽  
Rate Of Growth ◽  
Second Moments ◽  
Mean Temperature ◽  
The Mean

Abstract. Owing to the analogy between the solute and heat transport processes, it can be expected that the rate of growth of the spatial second moments of the heat flux in a heterogeneous aquifer over relatively large space scales is greater than that predicted by applying the classical heat transport model. The motivation of stochastic analysis of heat transport at the field scale is therefore to quantify the enhanced growth of the field-scale second moments caused by the spatially varying specific discharge field. Within the framework of stochastic theory, an effective advection-dispersion equation containing effective parameters (namely, the macrodispersion coefficients) is developed to model the mean temperature field. The rate of growth of the field-scale spatial second moments of the mean temperature field in the principal coordinate directions is described by the macrodispersion coefficient. The variance of the temperature field is also developed to characterize the reliability to be anticipated in applying the mean heat transport model. It is found that the heterogeneity of the medium and the correlation length of the log hydraulic conductivity are important in enhancing the field-scale heat advection, while the effective thermal conductivity plays the role in reducing the field-scale heat advection.

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