Artículos de revistas: "Reactive transport model"

1

Keum, D. K., and P. S. Hahn. "A coupled reactive chemical transport model:." Computers & Geosciences 29, no. 4 (2003): 431–45. http://dx.doi.org/10.1016/s0098-3004(02)00120-6.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Huang, Po-Wei, Bernd Flemisch, Chao-Zhong Qin, Martin O. Saar, and Anozie Ebigbo. "Validating the Nernst–Planck transport model under reaction-driven flow conditions using RetroPy v1.0." Geoscientific Model Development 16, no. 16 (2023): 4767–91. http://dx.doi.org/10.5194/gmd-16-4767-2023.

Texto completo

Resumen

Abstract. Reactive transport processes in natural environments often involve many ionic species. The diffusivities of ionic species vary. Since assigning different diffusivities in the advection–diffusion equation leads to charge imbalance, a single diffusivity is usually used for all species. In this work, we apply the Nernst–Planck equation, which resolves unequal diffusivities of the species in an electroneutral manner, to model reactive transport. To demonstrate the advantages of the Nernst–Planck model, we compare the simulation results of transport under reaction-driven flow conditions using the Nernst–Planck model with those of the commonly used single-diffusivity model. All simulations are also compared to well-defined experiments on the scale of centimeters. Our results show that the Nernst–Planck model is valid and particularly relevant for modeling reactive transport processes with an intricate interplay among diffusion, reaction, electromigration, and density-driven convection.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Maher, Kate, and K. Ulrich Mayer. "The Art of Reactive Transport Model Building." Elements 15, no. 2 (2019): 117–18. http://dx.doi.org/10.2138/gselements.15.2.117.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Tsai, Kuochen, Paul A. Gillis, Subrata Sen, and Rodney O. Fox. "A Finite-Mode PDF Model for Turbulent Reacting Flows." Journal of Fluids Engineering 124, no. 1 (2001): 102–7. http://dx.doi.org/10.1115/1.1431546.

Texto completo

Resumen

The recently proposed multi-environment model, R. O. Fox, 1998, “On the Relationship between Lagrangian Micromixing Models and Computational Fluid Dynamics,” Chem. Eng. Proc., Vol. 37, pp. 521–535. J. Villermaux and J. C. Devillon, 1994, “A Generalized Mixing Model for Initial Contacting of Reactive Fluids,” Chem. Eng. Sci., Vol. 49, p. 5127, provides a new category of modeling techniques that can be employed to resolve the turbulence-chemistry interactions found in reactive flows. By solving the Eulerian transport equations for volume fractions and chemical species simultaneously, the local concentrations of chemical species in each environment can be obtained. Assuming micromixing occurs only in phase space, the well-known IEM (interaction by exchange with the mean) model can be applied to close the micromixing term. This simplification allows the model to use micromixing timescales obtained from more sophisticated models and can be applied to any number of environments. Although the PDF shape doesn’t change under this assumption, the interaction between turbulence and chemistry can be resolved up to the second moments without any ad-hoc assumptions for the mean reaction rates. Furthermore, the PDF shape is found to have minimal effect on mean reaction rates for incompressible turbulent reacting flows. In this formulation, a spurious dissipation term arises in the transport equation of the scalar variances due to the use of Eulerian transport equations. A procedure is proposed to eliminate this spurious term. The model is applied to simulate the experiment of S. Komori, et al., 1993, “Measurements of Mass Flux in a Turbulent Liquid Flow With a Chemical Reaction,” AIChE J., Vol. 39, pp. 1611–1620, for a reactive mixing layer and the experiment of K. Li and H. Toor, 1986, “Turbulent Reactive Mixing With a Series Parallel reaction: Effect of Mixing on Yield,” AIChE J., Vol. 32, pp. 1312–1320, with a two-step parallel/consecutive reaction. The results are found to be in good agreement with the experimental data of Komori et al. and the PDF simulation of K. Tsai and R. Fox, 1994, “PDF Simulation of a Turbulent Series-Parallel Reaction in an Axisymmetric Reactor,” Chem. Eng. Sci., Vol. 49, pp. 5141–5158, for the experiment of Li and Toor. The resulting model is implemented in the commercial CFD code, FLUENT,1 and can be applied with any number of species and reactions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Robin, Degrave, Cockx Arnaud, and Schmitz Philippe. "Model of Reactive Transport within a Light Photocatalytic Textile." International Journal of Chemical Reactor Engineering 14, no. 1 (2016): 269–81. http://dx.doi.org/10.1515/ijcre-2015-0060.

Texto completo

Resumen

AbstractThis paper deals with the 3D-modeling of the reactive transport within a light photocatalytic textile used to decontaminate industrial effluents. The model consists of the coupling of fluid flow governing equations, species convection diffusion equations and a heterogeneous reaction equation. It is solved numerically on a Representative Volume Element (RVE) of the textile, i.e. at the microscopic scale regarding the industrial photocatalytic reactor using Comsol Multiphysics software. In a preliminary approach, the reactive transport model was first applied in a 2D simple geometry to verify its accuracy in terms of mass balance of the species. Then successive simulations using pseudo-periodic boundary conditions were performed in the RVE and the depollution efficiency along the textile length is analysed in terms of pollutant concentration. A sensitivity analysis was done to reveal the relative importance of the kinetic and hydrodynamic parameters in prediction of pollutant concentration fields in the RVE. It was found that a high adsorption rate associated with a low permeable fabric maximizes the amount of treated fluid. Finally the performances of a typical reactor composed of a stack of textiles were investigated. Results show a significant improvement of depollution efficiency of this particular configuration compared to single textiles in parallel.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Seetharam, Suresh Channarayapatna, Hywel Rhys Thomas, and Philip James Vardon. "Nonisothermal Multicomponent Reactive Transport Model for Unsaturated Soil." International Journal of Geomechanics 11, no. 2 (2011): 84–89. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0000018.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Heidari, Peyman, Li Li, Lixin Jin, Jennifer Z. Williams, and Susan L. Brantley. "A reactive transport model for Marcellus shale weathering." Geochimica et Cosmochimica Acta 217 (November 2017): 421–40. http://dx.doi.org/10.1016/j.gca.2017.08.011.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Cuch, Daniel A., Diana Rubio, and Claudio D. El Hasi. "Two-Dimensional Continuous Model in Bimolecular Reactive Transport." Open Journal of Fluid Dynamics 13, no. 01 (2023): 47–60. http://dx.doi.org/10.4236/ojfd.2023.131004.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Vu, Phuong Thanh, Chuen-Fa Ni, Wei-Ci Li, I.-Hsien Lee, and Chi-Ping Lin. "Particle-Based Workflow for Modeling Uncertainty of Reactive Transport in 3D Discrete Fracture Networks." Water 11, no. 12 (2019): 2502. http://dx.doi.org/10.3390/w11122502.

Texto completo

Resumen

Fractures are major flow paths for solute transport in fractured rocks. Conducting numerical simulations of reactive transport in fractured rocks is a challenging task because of complex fracture connections and the associated nonuniform flows and chemical reactions. The study presents a computational workflow that can approximately simulate flow and reactive transport in complex fractured media. The workflow involves a series of computational processes. Specifically, the workflow employs a simple particle tracking (PT) algorithm to track flow paths in complex 3D discrete fracture networks (DFNs). The PHREEQC chemical reaction model is then used to simulate the reactive transport along particle traces. The study illustrates the developed workflow with three numerical examples, including a case with a simple fracture connection and two cases with a complex fracture network system. Results show that the integration processes in the workflow successfully model the tetrachloroethylene (PCE) and trichloroethylene (TCE) degradation and transport along particle traces in complex DFNs. The statistics of concentration along particle traces enables the estimations of uncertainty induced by the fracture structures in DFNs. The types of source contaminants can lead to slight variations of particle traces and influence the long term reactive transport. The concentration uncertainty can propagate from parent to daughter compounds and accumulate along with the transport processes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Hojabri, Shirin, Ljiljana Rajic, and Akram N. Alshawabkeh. "Transient reactive transport model for physico-chemical transformation by electrochemical reactive barriers." Journal of Hazardous Materials 358 (September 2018): 171–77. http://dx.doi.org/10.1016/j.jhazmat.2018.06.051.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Sund, Nicole, Giovanni Porta, Diogo Bolster, and Rishi Parashar. "A Lagrangian Transport Eulerian Reaction Spatial (LATERS) Markov Model for Prediction of Effective Bimolecular Reactive Transport." Water Resources Research 53, no. 11 (2017): 9040–58. http://dx.doi.org/10.1002/2017wr020821.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Sochaczewski, Łukasz, Anthony Stockdale, William Davison, Wlodek Tych, and Hao Zhang. "A three-dimensional reactive transport model for sediments, incorporating microniches." Environmental Chemistry 5, no. 3 (2008): 218. http://dx.doi.org/10.1071/en08006.

Texto completo

Resumen

Environmental context. Modelling of discrete sites of diagenesis in sediments (microniches) has typically been performed in 1-D and has involved a limited set of components. Here we present a new 3-D model for microniches within a traditional vertical sequence of redox reactions, and show example modelled niches of a range of sizes, close to the sediment–water interface. Microniche processes may have implications for understanding trace metal diagenesis, via formation of sulfides. The model provides a quantitative framework for examining microniche data and concepts. Abstract. Most reactive transport models have represented sediments as one-dimensional (1-D) systems and have solely considered the development of vertical concentration gradients. However, application of recently developed microscale and 2-D measurement techniques have demonstrated more complicated solute structures in some sediments, including discrete localised sites of depleted oxygen, and elevated trace metals and sulfide, referred to as microniches. A model of transport and reaction in sediments that can simulate the dynamic development of concentration gradients occurring in 3-D was developed. Its graphical user interface allows easy input of user-specified reactions and provides flexible schemes that prioritise their execution. The 3-D capability was demonstrated by quantitative modelling of hypothetical solute behaviour at organic matter microniches covering a range of sizes. Significant effects of microniches on the profiles of oxygen and nitrate are demonstrated. Sulfide is shown to be readily generated in microniches within 1 cm of the sediment surface, provided the diameter of the reactive organic material is greater than 1 mm. These modelling results illustrate the geochemical complexities that arise when processes occur in 3-D and demonstrate the need for such a model. Future use of high-resolution measurement techniques should include the collection of data for relevant major components, such as reactive iron and manganese oxides, to allow full, multicomponent modelling of microniche processes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Ukrainczyk, Neven, Oliver Vogt, and Eduardus A. B. Koenders. "Reactive Transport Numerical Model for Durability of Geopolymer Materials." Advances in Chemical Engineering and Science 06, no. 04 (2016): 355–63. http://dx.doi.org/10.4236/aces.2016.64036.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Tartakovsky, Alexandre M., Timothy D. Scheibe, and Paul Meakin. "Pore-Scale Model for Reactive Transport and Biomass Growth." Journal of Porous Media 12, no. 5 (2009): 417–34. http://dx.doi.org/10.1615/jpormedia.v12.i5.30.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Deng, Hang, Sergi Molins, Carl Steefel, et al. "A 2.5D Reactive Transport Model for Fracture Alteration Simulation." Environmental Science & Technology 50, no. 14 (2016): 7564–71. http://dx.doi.org/10.1021/acs.est.6b02184.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Hongyun, Ma, Samper Javier, and Xin Xin. "Modeling of titration experiments by a reactive transport model." Mining Science and Technology (China) 21, no. 2 (2011): 273–76. http://dx.doi.org/10.1016/j.mstc.2011.02.006.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Acero, Patricia, Carlos Ayora, Jesús Carrera, Maarten W. Saaltink, and Sebastiá Olivella. "Multiphase flow and reactive transport model in vadose tailings." Applied Geochemistry 24, no. 7 (2009): 1238–50. http://dx.doi.org/10.1016/j.apgeochem.2009.03.008.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Golparvar, Amir, Matthias Kästner, and Martin Thullner. "P3D-BRNS v1.0.0: a three-dimensional, multiphase, multicomponent, pore-scale reactive transport modelling package for simulating biogeochemical processes in subsurface environments." Geoscientific Model Development 17, no. 2 (2024): 881–98. http://dx.doi.org/10.5194/gmd-17-881-2024.

Texto completo

Resumen

Abstract. The porous microenvironment of soil offers various environmental functions which are governed by physical and reactive processes. Understanding reactive transport processes in porous media is essential for many natural systems (soils, aquifers, aquatic sediments or subsurface reservoirs) or technological processes (water treatment or ceramic and fuel cell technologies). In particular, in the vadose zone of the terrestrial subsurface the spatially and temporally varying saturation of the aqueous and the gas phase leads to systems that involve complex flow and transport processes as well as reactive transformations of chemical compounds in the porous material. To describe these interacting processes and their dynamics at the pore scale requires a well-suited modelling framework accounting for the proper description of all relevant processes at a high spatial resolution. Here we present P3D-BRNS as a new open-source modelling toolbox harnessing the core libraries of OpenFOAM and coupled externally to the Biogeochemical Reaction Network Simulator (BRNS). The native OpenFOAM volume-of-fluid solver is extended to have an improved representation of the fluid–fluid interface. The solvers are further developed to couple the reaction module which can be tailored for a specific reactive transport simulation. P3D-RBNS is benchmarked against three different flow and reactive transport processes: (1) fluid–fluid configuration in a capillary corner, (2) mass transfer across the fluid–fluid interface and (3) microbial growth with a high degree of accuracy. Our model allows for simulation of the spatio-temporal distribution of all biochemical species in the porous structure (obtained from μ-CT images), for conditions that are commonly found in the laboratory and environmental systems. With our coupled computational model, we provide a reliable and efficient tool for simulating multiphase, reactive transport in porous media.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Lu, Chunhui, Zhiyuan Wang, Yue Zhao, et al. "A mobile-mobile transport model for simulating reactive transport in connected heterogeneous fields." Journal of Hydrology 560 (May 2018): 97–108. http://dx.doi.org/10.1016/j.jhydrol.2018.02.073.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Yu, Qian, Yanxin Wang, Xianjun Xie, and Matthew Currell. "Reactive transport model for predicting arsenic transport in groundwater system in Datong Basin." Journal of Geochemical Exploration 190 (July 2018): 245–52. http://dx.doi.org/10.1016/j.gexplo.2018.03.008.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Tebes-Stevens, Caroline L., Felipe Espinoza, and Albert J. Valocchi. "Evaluating the sensitivity of a subsurface multicomponent reactive transport model with respect to transport and reaction parameters." Journal of Contaminant Hydrology 52, no. 1-4 (2001): 3–27. http://dx.doi.org/10.1016/s0169-7722(01)00151-6.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Tranter, Morgan, Maria Wetzel, Marco De Lucia, and Michael Kühn. "Reactive transport model of kinetically controlled celestite to barite replacement." Advances in Geosciences 56 (October 8, 2021): 57–65. http://dx.doi.org/10.5194/adgeo-56-57-2021.

Texto completo

Resumen

Abstract. Barite formation is of concern for many utilisations of the geological subsurface, ranging from oil and gas extraction to geothermal reservoirs. It also acts as a scavenger mineral for the retention of radium within nuclear waste repositories. The impact of its precipitation on flow properties has been shown to vary by many orders of magnitude, emphasising the need for robust prediction models. An experimental flow-through column setup on the laboratory scale investigating the replacement of celestite (SrSO4) with barite (BaSO4) for various input barium concentrations was taken as a basis for modelling. We provide here a comprehensive, geochemical modelling approach to simulate the experiments. Celestite dissolution kinetics, as well as subsequent barite nucleation and crystal growth were identified as the most relevant reactive processes, which were included explicitly in the coupling. A digital rock representation of the granular sample was used to derive the initial inner surface area. Medium (10 mM) and high (100 mM) barium input concentration resulted in a comparably strong initial surge of barite nuclei formation, followed by continuous grain overgrowth and finally passivation of celestite. At lower input concentrations (1 mM), nuclei formation was significantly less, resulting in fewer but larger barite crystals and a slow moving reaction front with complete mineral replacement. The modelled mole fractions of the solid phase and effluent chemistry match well with previous experimental results. The improvement compared to models using empirical relationships is that no a-priori knowledge on prevailing supersaturations in the system is needed. For subsurface applications utilising reservoirs or reactive barriers, where barite precipitation plays a role, the developed geochemical model is of great benefit as only solute concentrations are needed as input for quantified prediction of alterations.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Simpson, Matthew J., and Liam C. Morrow. "Analytical model of reactive transport processes with spatially variable coefficients." Royal Society Open Science 2, no. 5 (2015): 140348. http://dx.doi.org/10.1098/rsos.140348.

Texto completo

Resumen

Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v ( x ), or spatially variable decay rate, k ( x ), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v ( x ) and k ( x ). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v ( x ) and k ( x ). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Addassi, Mouadh, Victor Marcos-Meson, Wolfgang Kunther, Hussein Hoteit, and Alexander Michel. "A Methodology for Optimizing the Calibration and Validation of Reactive Transport Models for Cement-Based Materials." Materials 15, no. 16 (2022): 5590. http://dx.doi.org/10.3390/ma15165590.

Texto completo

Resumen

Reactive transport models are useful tools in the development of cement-based materials. The output of cement-related reactive transport models is primarily regarded as qualitative and not quantitative, mainly due to limited or missing experimental validation. This paper presents an approach to optimize the calibration process of reactive transport models for cement-based materials, using the results of several short-term experiments. A quantitative comparison of changes in the hydrate phases (measured using TGA and XRD) and exposure solution (measured using ICP-OES) was used to (1) establish a representative chemical model, limiting the number of hydrate phases and dissolved species, and (2) calibrate the transport processes by only modeling the initial tortuosity. A case study comprising the early age carbonation of cement is presented to demonstrate the approach. The results demonstrate that the inclusion of a microstructure model in our framework minimizes the impact of the initial tortuosity factor as a fitting parameter for the transport processes. The proposed approach increases the accuracy of reactive transport models and, thus, allowing for more realistic modeling of long-term exposure.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Algive, Lionnel, Samir Bekri, and Olga Vizika. "Pore-Network Modeling Dedicated to the Determination of the Petrophysical-Property Changes in the Presence of Reactive Fluid." SPE Journal 15, no. 03 (2010): 618–33. http://dx.doi.org/10.2118/124305-pa.

Texto completo

Resumen

Summary A pore-network model (PNM) is an efficient tool to account for phenomena occurring at the pore scale. Its explicit 3D network of pores interconnected by throats represents an easy way to consider the topology and geometry effects on upscaled and homogenized petrophysical parameters. In particular, this modeling approach is appropriate to study the rock/fluid interactions. It can provide quantitative information both on the effective transport property modifications caused by the reactions and on the structure evolution resulting from dissolution/precipitation mechanisms. The model developed is based on the resolution of the macroscopic reactive transport equation between the nodes of the network. By upscaling the results, we then determined the effective transport properties at the core scale. A sensitivity study on reactive and flow regimes has been conducted in the case of single-phase flow in the limit of long times. It has been observed that the mean reactive solute velocity and dispersion can vary up to one order of magnitude compared with the tracer values because of the concentration-profile heterogeneity at the pore scale resulting from the surface reactions. As for the reactive apparent coefficient, when the kinetics is limited by the mass transfer, it can decrease by several orders of magnitude with regard to that calculated by the usual perfect-mixing assumption. That is why scale factors should be added to the classical macroscopic transport equation implemented in reservoir simulators to predict accurately the reactive flow effects. For each study case, we also obtained the permeability variation vs. the porosity evolution in a physical way that accounts for reactive transport conditions. It appears that the wall-deformation pattern and its effect on petrophysical properties must be explained by considering both microscopic and macroscopic scales of the reactive transport, each one governed by a dimensionless number comparing reaction and transport characteristic times. This work helps improve the understanding of surface-reactions effects on reactive flow on the one hand and on permeability and porosity modifications on the other. Using the PNM approach, scale-factor parameters and permeability-vs.-porosity relations can be determined for various rock types and reactive flow regimes. Once integrated as inputs in a reservoir simulator, these relations form a powerful and convenient means of enhancing the modeling accuracy of the change in petrophysical properties during injection of a reactive fluid, such as brine rich in carbon dioxide (CO2).

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Shavelzon, Evgeny, and Yaniv Edery. "Shannon entropy of transport self-organization due to dissolution–precipitation reaction at varying Peclet numbers in initially homogeneous porous media." Hydrology and Earth System Sciences 28, no. 8 (2024): 1803–26. http://dx.doi.org/10.5194/hess-28-1803-2024.

Texto completo

Resumen

Abstract. Dissolution and precipitation processes in reactive transport in porous media are ubiquitous in a multitude of contexts within the field of Earth sciences. In particular, the dynamic interaction between the reactive dissolution and precipitation processes and the solute transport is of interest as it is capable of giving rise to the emergence of preferential flow paths in the porous host matrix. It has been shown that the emergence of preferential flow paths can be considered to be a manifestation of transport self-organization in porous media as these create spatial gradients that distance the system from the state of perfect mixing and allow for a faster and more efficient fluid transport through the host matrix. To investigate the dynamic feedback between the transport and the reactive processes in the field and its influence on the emergence of transport self-organization, we consider a two-dimensional Darcy-scale formulation of a reactive-transport setup, where the precipitation and dissolution of the host matrix are driven by the injection of an acid compound, establishing local equilibrium with the resident fluid and an initially homogeneous porous matrix, composed of a calcite mineral. The coupled reactive process is simulated in a series of computational analyses employing the Lagrangian particle-tracking (LPT) approach, capable of capturing the subtleties of the multiple-scale heterogeneity phenomena. We employ the Shannon entropy to quantify the emergence of self-organization in the field, which we define as a relative reduction in entropy compared to its maximum value. Scalability of the parameters, which characterize the evolution of the reactive process, with the Peclet number in an initially homogeneous field is derived using a simple one-dimensional ADRE model with a linear adsorption reaction term and is then confirmed through numerical simulations, with the global reaction rate, the mean value, and the variance of the hydraulic-conductivity distribution in the field all exhibiting dependency on the reciprocal of the Peclet number. Our findings show that transport self-organization in an initially homogeneous field increases with time, along with the emergence of the field heterogeneity due to the interaction between the transport and reactive processes. By studying the influence of the Peclet number on the reactive process, we arrive at a conclusion that self-organization is more pronounced in diffusion-dominated flows, characterized by small Peclet values. The self-organization of the breakthrough curve exhibits the opposite tendencies, which are observed from the perspective of a thermodynamic analogy. The hydraulic power, required to maintain the driving head pressure difference between the inlet and outlet of the field, was shown to increase with the increasing variance, as well as with the increasing mean value of the hydraulic-conductivity distribution in the field, using a simple analytic model. This was confirmed by numerical experiments. This increase in power, supplied to the flow in the field, results in an increase in the level of transport self-organization. Employing a thermodynamic framework to investigate the dynamic reaction–transport interaction in porous media may prove to be beneficial whenever the need exists to establish relations between the intensification of the preferential flow path phenomenon, represented by a decline in the Shannon entropy of the transport, with the amount of reaction that occurred in the porous medium and the change in its heterogeneity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Aizhulov, D. Y., N. M. Shayakhmetov, and A. Kaltayev. "Quantitative Model of the Formation Mechanism of the Rollfront Uranium Deposits." Eurasian Chemico-Technological Journal 20, no. 3 (2018): 213. http://dx.doi.org/10.18321/ectj724.

Texto completo

Resumen

The rollfront type deposits are crescent shaped accumulation of mineralization including uranium, selenium, molybdenum in reduced permeable sandstones. It generally forms within a geochemical barrier between mostly reduced and predominantly oxidized environments. Redox reactions between oxidant and reductant creates favorable conditions for uranium precipitation, while constant flow of oxidant continuously dissolves uranium minerals thereby creating a reactive transport. Several previous works had either focused on the characteristics of the rollfront type deposits, or on the description of chemical and geological processes involved in their genesis. Based on these previous works, authors aimed to mimic laboratory experiments numerically by reactive flow and numerical simulation. Data from one particular experiment was used to determine reaction rates between reactants to produce a model of reactive transport and chemical processes involved in the formation of rollfront type deposits. The resulting model was used to identify the causes of crescent like formations and to determine main mechanisms influencing rollfront evolution. A better understanding and simulation of the mechanism involved in the formation of rollfront type deposits and their properties would contribute to decreased exploration and production costs of commodities trapped within such accumulations. The results of this work can be used to model other deposits formed through infiltration and subsequent precipitation of various minerals at the redox interface.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Celia, Michael A., J. Scott Kindred, and Ismael Herrera. "Contaminant transport and biodegradation: 1. A numerical model for reactive transport in porous media." Water Resources Research 25, no. 6 (1989): 1141–48. http://dx.doi.org/10.1029/wr025i006p01141.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Sternagel, Alexander, Ralf Loritz, Julian Klaus, Brian Berkowitz, and Erwin Zehe. "Simulation of reactive solute transport in the critical zone: a Lagrangian model for transient flow and preferential transport." Hydrology and Earth System Sciences 25, no. 3 (2021): 1483–508. http://dx.doi.org/10.5194/hess-25-1483-2021.

Texto completo

Resumen

Abstract. We present a method to simulate fluid flow with reactive solute transport in structured, partially saturated soils using a Lagrangian perspective. In this context, we extend the scope of the Lagrangian Soil Water and Solute Transport Model (LAST) (Sternagel et al., 2019) by implementing vertically variable, non-linear sorption and first-order degradation processes during transport of reactive substances through a partially saturated soil matrix and macropores. For sorption, we develop an explicit mass transfer approach based on Freundlich isotherms because the common method of using a retardation factor is not applicable in the particle-based approach of LAST. The reactive transport method is tested against data of plot- and field-scale irrigation experiments with the herbicides isoproturon and flufenacet at different flow conditions over various periods. Simulations with HYDRUS 1-D serve as an additional benchmark. At the plot scale, both models show equal performance at a matrix-flow-dominated site, but LAST better matches indicators of preferential flow at a macropore-flow-dominated site. Furthermore, LAST successfully simulates the effects of adsorption and degradation on the breakthrough behaviour of flufenacet with preferential leaching and remobilization. The results demonstrate the feasibility of the method to simulate reactive solute transport in a Lagrangian framework and highlight the advantage of the particle-based approach and the structural macropore domain to simulate solute transport as well as to cope with preferential bypassing of topsoil and subsequent re-infiltration into the subsoil matrix.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Formaggia, Luca, Alessio Fumagalli, and Anna Scotti. "A multi-layer reactive transport model for fractured porous media." Mathematics in Engineering 4, no. 1 (2021): 1–32. http://dx.doi.org/10.3934/mine.2022008.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Liu, Jiangjin, Pablo A. García-Salaberri, and Iryna V. Zenyuk. "Bridging Scales to Model Reactive Diffusive Transport in Porous Media." Journal of The Electrochemical Society 167, no. 1 (2020): 013524. http://dx.doi.org/10.1149/2.0242001jes.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Appelo, C. A. J., and Massimo Rolle. "PHT3D: A Reactive Multicomponent Transport Model for Saturated Porous Media." Ground Water 48, no. 5 (2010): 627–32. http://dx.doi.org/10.1111/j.1745-6584.2010.00732.x.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Liu, Chen Wuing, and T. N. Narasimhan. "Redox-controlled multiple-species reactive chemical transport: 1. Model development." Water Resources Research 25, no. 5 (1989): 869–82. http://dx.doi.org/10.1029/wr025i005p00869.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Samper, Javier, Chuanhe Lu, and Luis Montenegro. "Reactive transport model of interactions of corrosion products and bentonite." Physics and Chemistry of the Earth, Parts A/B/C 33 (January 2008): S306—S316. http://dx.doi.org/10.1016/j.pce.2008.10.009.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Islam, J., and N. Singhal. "A one-dimensional reactive multi-component landfill leachate transport model." Environmental Modelling & Software 17, no. 6 (2002): 531–43. http://dx.doi.org/10.1016/s1364-8152(02)00009-9.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Kazemi Nia Korrani, Aboulghasem, Kamy Sepehrnoori, and Mojdeh Delshad. "Coupling IPhreeqc with UTCHEM to model reactive flow and transport." Computers & Geosciences 82 (September 2015): 152–69. http://dx.doi.org/10.1016/j.cageo.2015.06.004.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Tian, Zhiwei, Huilin Xing, Yunliang Tan, Sai Gu, and Suzanne D. Golding. "Reactive transport LBM model for CO2 injection in fractured reservoirs." Computers & Geosciences 86 (January 2016): 15–22. http://dx.doi.org/10.1016/j.cageo.2015.10.002.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Navarre-Sitchler, Alexis, Carl I. Steefel, Peter B. Sak, and Susan L. Brantley. "A reactive-transport model for weathering rind formation on basalt." Geochimica et Cosmochimica Acta 75, no. 23 (2011): 7644–67. http://dx.doi.org/10.1016/j.gca.2011.09.033.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

van Wijngaarden, W. K., L. A. van Paassen, F. J. Vermolen, G. A. M. van Meurs, and C. Vuik. "A Reactive Transport Model for Biogrout Compared to Experimental Data." Transport in Porous Media 111, no. 3 (2015): 627–48. http://dx.doi.org/10.1007/s11242-015-0615-5.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Lucille, P. L., A. Burnol, and Ph Ollar. "Chemtrap: a hydrogeochemical model for reactive transport in porous media." Hydrological Processes 14, no. 13 (2000): 2261–77. http://dx.doi.org/10.1002/1099-1085(200009)14:13<2261::aid-hyp27>3.0.co;2-l.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Kirste, Dirk, Julie K. Pearce, Sue D. Golding, and Grant K. W. Dawson. "Trace element mobility during CO2 storage: application of reactive transport modelling." E3S Web of Conferences 98 (2019): 04007. http://dx.doi.org/10.1051/e3sconf/20199804007.

Texto completo

Resumen

The geologic storage of CO2 carries both physical and chemical risks to the environment. In order to reduce those risks, it is necessary to provide predictive capabilities for impacts so that strategies can be developed to monitor, identify and mitigate potential problems. One area of concern is related to water quality both in the reservoir and in overlying aquifers. In this study we report the critical steps required to develop chemically constrained reactive transport models (RTM) that can be used to address risk assessment associated with water quality. The data required to produce the RTM includes identifying the individual hydrostratigraphic units and defining the mineral and chemical composition to sufficient detail for the modelling. This includes detailed mineralogy, bulk chemical composition, reactive mineral phase chemical composition and the identification of the occurrence and mechanisms of mobilisation of any trace elements of interest. Once the required detail is achieved the next step involves conducting experiments to determine the evolution of water chemistry as reaction proceeds preferably under varying elevated CO2 fugacities with and without impurities. Geochemical modelling of the experiments is then used for characterising the reaction pathways of the different hydrostratigraphic units. The resultant geochemical model inputs can then be used to develop the chemical components of a reactive transport model.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Bagheri, Niksa Mohammadi, Gabor Závodszky, and Alfons G. Hoekstra. "The impact of clot permeability on platelet fluxes toward its surface." PLOS ONE 20, no. 3 (2025): e0317828. https://doi.org/10.1371/journal.pone.0317828.

Texto completo

Resumen

Platelet aggregation is regulated by a series of chemical reactions that control platelet adhesion on a thrombogenic surface. These reactions are influenced by the complex interaction between reaction kinetics and hemodynamics. This study systematically investigates the transport of platelets, considering the interaction between flow-mediated mass transfer mechanisms and reaction kinetics as a function of clot permeability. A two-dimensional finite element model is developed to replicate static blood flow, platelet transport, and adhesion on a semi-elliptical and semi-circular structure representing permeable clots. The platelet-clot interface interactions are extensively investigated using a hindered transport model, focusing on clot permeabilities, reaction rates, and flow conditions. In the case of clots with highly reactive surfaces, an increase in clot permeability can lead up to four-fold increase in total platelet flux compared to non-permeable clots due to differences in transport environments.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Yeh, Gour-Tsyh, and Vijay S. Tripathi. "A Model for Simulating Transport of Reactive Multispecies Components: Model Development and Demonstration." Water Resources Research 27, no. 12 (1991): 3075–94. http://dx.doi.org/10.1029/91wr02028.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Langergraber, G. "Simulation of subsurface flow constructed wetlands - results and further research needs." Water Science and Technology 48, no. 5 (2003): 157–66. http://dx.doi.org/10.2166/wst.2003.0308.

Texto completo

Resumen

Simulation of constructed wetlands has two main tasks: to obtain a better understanding of the processes in constructed wetlands, and to check and optimise existing design criteria. This paper shows simulation results for two indoor pilot-scale constructed wetlands for wastewater and surface water treatment respectively. The results presented and discussed are mainly focussed on the hydraulic behaviour of the constructed wetland systems. In addition results of reactive transport simulations with CW2D are shown. The multi-component reactive transport model CW2D (Constructed Wetlands 2 Dimensional) was developed to model transport and reactions of the main constituents of wastewater (organic matter, nitrogen, and phosphorus) in subsurface flow constructed wetlands. For the pilot-scale constructed wetlands a calibration of the flow model was possible and therefore the results of the reactive transport simulations with CW2D fit the measured data well. The further research needs regarding the simulation of subsurface flow constructed wetlands are discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Lemke, D., R. González-Pinzón, Z. Liao, et al. "Sorption and transformation of the reactive tracers resazurin and resorufin in natural river sediments." Hydrology and Earth System Sciences 18, no. 8 (2014): 3151–63. http://dx.doi.org/10.5194/hess-18-3151-2014.

Texto completo

Resumen

Abstract. Resazurin (Raz) and its reaction product resorufin (Rru) have increasingly been used as reactive tracers to quantify metabolic activity and hyporheic exchange in streams. Previous work has indicated that these compounds undergo sorption in stream sediments. We present laboratory experiments on Raz and Rru transport, sorption, and transformation, consisting of 4 column and 72 batch tests using 2 sediments with different physicochemical properties under neutral (pH = 7) and alkaline (pH = 9) conditions. The study aimed at identifying the key processes of reactive transport of Raz and Rru in streambed sediments and the experimental setup best suited for their determination. Data from column experiments were simulated by a travel-time-based model accounting for physical transport, equilibrium and kinetic sorption, and three first-order reactions. We derived the travel-time distributions directly from the breakthrough curve (BTC) of the conservative tracer, fluorescein, rather than from fitting an advective-dispersive transport model, and inferred from those distributions the transfer functions of Raz and Rru, which provided conclusive approximations of the measured BTCs. The most likely reactive transport parameters and their uncertainty were determined by a Markov chain–Monte Carlo approach. Sorption isotherms of both compounds were obtained from batch experiments. We found that kinetic sorption dominates sorption of both Raz and Rru, with characteristic timescales of sorption in the order of 12 to 298 min. Linear sorption models for both Raz and Rru appeared adequate for concentrations that are typically applied in field tracer tests. The proposed two-site sorption model helps to interpret transient tracer tests using the Raz–Rru system.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Keller, Tobias, and Jenny Suckale. "A continuum model of multi-phase reactive transport in igneous systems." Geophysical Journal International 219, no. 1 (2019): 185–222. http://dx.doi.org/10.1093/gji/ggz287.

Texto completo

Resumen

SUMMARY Multiphase reactive transport processes are ubiquitous in igneous systems. A challenging aspect of modelling igneous phenomena is that they range from solid-dominated porous to liquid-dominated suspension flows and therefore entail a wide spectrum of rheological conditions, flow speeds and length scales. Most previous models have been restricted to the two-phase limits of porous melt transport in deforming, partially molten rock and crystal settling in convecting magma bodies. The goal of this paper is to develop a framework that can capture igneous system from source to surface at all phase proportions including not only rock and melt but also an exsolved volatile phase. Here, we derive an n-phase reactive transport model building on the concepts of Mixture Theory, along with principles of Rational Thermodynamics and procedures of Non-equilibrium Thermodynamics. Our model operates at the macroscopic system scale and requires constitutive relations for fluxes within and transfers between phases, which are the processes that together give rise to reactive transport phenomena. We introduce a phase- and process-wise symmetrical formulation for fluxes and transfers of entropy, mass, momentum and volume, and propose phenomenological coefficient closures that determine how fluxes and transfers respond to mechanical and thermodynamic forces. Finally, we demonstrate that the known limits of two-phase porous and suspension flow emerge as special cases of our general model and discuss some ramifications for modelling pertinent two- and three-phase flow problems in igneous systems.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

CVETKOVIC, V., J. O. SELROOS, and H. CHENG. "Transport of reactive tracers in rock fractures." Journal of Fluid Mechanics 378 (January 10, 1999): 335–56. http://dx.doi.org/10.1017/s0022112098003450.

Texto completo

Resumen

Transport of tracers subject to mass transfer reactions in single rock fractures is investigated. A Lagrangian probabilistic model is developed where the mass transfer reactions are diffusion into the rock matrix and subsequent sorption in the matrix, and sorption on the fracture surface as well as on gauge (infill) material in the fracture. Sorption reactions are assumed to be linear, and in the general case kinetically controlled. The two main simplifying assumptions are that diffusion in the rock matrix is one-dimensional, perpendicular to the fracture plane, and the tracer is displaced within the fracture plane by advection only. The key feature of the proposed model is that advective transport and diffusive mass transfer are related in a dynamic manner through the flow equation. We have identified two Lagrangian random variables τ and β as key parameters which control advection and diffusive mass transfer, and are determined by the flow field. The probabilistic solution of the transport problem is based on the statistics of (τ, β), which we evaluated analytically using first-order expansions, and numerically using Monte Carlo simulations. To study (τ, β)-statistics, we assumed the ‘cubic law’ to be applicable locally, whereby the pressure field is described with the Reynolds lubrication equation. We found a strong correlation between τ and β which suggests a deterministic relationship β∼τ3/2; the exponent 3/2 is an artifact of the ‘cubic law’. It is shown that flow dynamics in fractures has a strong influence on the variability of τ and β, but a comparatively small impact on the relationship between τ and β. The probability distribution for the (decaying) tracer mass recovery is dispersed in the parameter space due to fracture aperture variability.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Tawfik, Ashraf M., and Mohamed Mokhtar Hefny. "Subdiffusive Reaction Model of Molecular Species in Liquid Layers: Fractional Reaction-Telegraph Approach." Fractal and Fractional 5, no. 2 (2021): 51. http://dx.doi.org/10.3390/fractalfract5020051.

Texto completo

Resumen

In recent years, different experimental works with molecular simulation techniques have been developed to study the transport of plasma-generated reactive species in liquid layers. Here, we improve the classical transport model that describes the molecular species movement in liquid layers via considering the fractional reaction–telegraph equation. We have considered the fractional equation to describe a non-Brownian motion of molecular species in a liquid layer, which have different diffusivities. The analytical solution of the fractional reaction–telegraph equation, which is defined in terms of the Caputo fractional derivative, is obtained by using the Laplace–Fourier technique. The profiles of species density with the mean square displacement are discussed in each case for different values of the time-fractional order and relaxation time.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Johnson, Raymond H., Charles J. Paradis, Ronald D. Kent, Aaron D. Tigar, and Paul W. Reimus. "Single-Well Push–Pull Tracer Test Analyses to Determine Aquifer Reactive Transport Parameters at a Former Uranium Mill Site (Grand Junction, Colorado)." Minerals 13, no. 2 (2023): 228. http://dx.doi.org/10.3390/min13020228.

Texto completo

Resumen

At a former uranium mill site where tailings have been removed, prior work has determined several potential ongoing secondary uranium sources. These include locations with uranium sorbed to organic carbon, uranium in the unsaturated zone, and uranium associated with the presence of gypsum. To better understand uranium mobility controls at the site, four single-well push–pull tests (with a drift phase) were completed with the goal of deriving aquifer flow and contaminant transport parameters for inclusion in a future sitewide reactive transport model. This goes beyond the traditional use of a constant sorption distribution coefficient (Kd) and allows for the evaluation of alternative remedial injection fluids, which can produce variable Kd values. Dispersion was first removed from the resulting data to determine possible reactions before conducting reactive transport simulations. These initial analyses indicated the potential need to include cation exchange, uranium sorption, and gypsum dissolution. A reactive transport model using multiple layers to account for partially penetrating wells was completed using the PHT-USG reactive transport modeling code and calibrated using PEST. The model results quantify the hydraulic conductivity and dispersion parameters using the injected tracer concentrations. Uranium sorption, cation exchange, and gypsum dissolution parameters were quantified by comparing the simulated versus observed geochemistry. All simulations required some cation exchange and calcite equilibrium, and one simulation required gypsum dissolution to improve the model fit for calcium and sulfate. Uranium sorption parameters were not strongly influenced by the other parameter values but were highly influenced by uranium concentrations during the drift phase, with possible kinetic rate limitations. Thus, a future recommendation for such push–pull tests is to collect more geochemical data during the drift phase. The final uranium sorption parameters were within the range of values determined from prior column testing. The flow and transport parameters derived from these single-well push–pull tests will provide initial parameters for any future sitewide reactive transport model.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Aggarwal, Mohit, Mame Cheikh Anta Ndiaye, and Jérôme Carrayrou. "Parameters estimation for reactive transport: A way to test the validity of a reactive model." Physics and Chemistry of the Earth, Parts A/B/C 32, no. 1-7 (2007): 518–29. http://dx.doi.org/10.1016/j.pce.2005.12.003.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Reactive transport model"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros