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Articoli di riviste sul tema "Solute transport modelling"

Autore: Grafiati

Pubblicato: 21 dicembre 2024

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1

Zaheer, Muhammad, Hadayat Ullah, Saad Ahmed Mashwani, Ehsan ul Haq, Syed Husnain Ali Shah e Fawaz Manzoor. "SOLUTE TRANSPORT MODELLING IN LOW-PERMEABILITY HOMOGENEOUS AND SATURATED SOIL MEDIA". Rudarsko-geološko-naftni zbornik 36, n. 2 (2021): 25–32. http://dx.doi.org/10.17794/rgn.2021.2.3.

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Fickian and non-Fickian behaviors were often detected for contaminant transport activity owed to the preferential flow and heterogeneity of soil media. Therefore, using diverse methods to measure such composite solute transport in soil media has become an important research topic for solute transport modeling in soil media. In this article, the continuous-time random walk (CTRW) model was applied to illustrate the relative concentration of transport in low-permeability homogeneous and saturated soil media. The solute transport development was also demonstrated with the convection-dispersion equation (CDE) and Two Region Model (TRM) for comparison. CXTFIT 2.1 software was used for CDE and TRM, and CTRW Matlab Toolbox v.3.1 for the CTRW simulation of the breakthrough curve. It was found that higher values of determination coefficient (R2) and lower values of root mean square error (RMSE) concerning the best fits of CDE, TRM, and CTRW. It was found that in the comparison of CDE, TRM, and CTRW, we tend to use CTRW to describe the transport behavior well because there are prevailing Fickian and non-Fickian transport. The CTRW gives better fitting results to the breakthrough curves (BTCs) when β has an increasing pattern towards 2.00. In this study, the variation of parameters in three methods was investigated and results showed that the CTRW modeling approach is more effective to determine non-reactive contaminants concentration in low-permeability soil media at small depths.

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Applegate, David, e Pete Appleyard. "Capability for Hydrogeochemical Modelling within Discrete Fracture Networks". Energies 15, n. 17 (26 agosto 2022): 6199. http://dx.doi.org/10.3390/en15176199.

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A new method for simulating solute transport and geochemical interactions within fractured rock is presented. This will be an important capability for assessing the safety of radioactive waste disposal facilities that are located within fractured crystalline bedrock. Specifically, the discrete fracture network (DFN) module within the ConnectFlow groundwater flow and transport software has been updated to: (i) simulate the advection and diffusion of more than one solute species (with the flow and transport equations coupled by the evolving density and viscosity); (ii) model the diffusion of solutes into the rock matrix between fractures; and (iii) utilise the iPhreeqc library to model chemical reactions involving solutes, minerals on fracture/pore surfaces and rock minerals. The performance of ConnectFlow’s DFN module has also been significantly improved via parallelisation which allows more complex calculations to be attempted. These developments are significant because hydrogeochemistry within fractured rock is more accurately represented in an explicit DFN, rather than using more approximate equivalent continuous porous medium (ECPM) methods. Illustrative calculations have been completed for the disposal facility for spent nuclear fuel at Olkiluoto in Finland, and the former candidate site for spent fuel disposal, Laxemar, in Sweden. These calculations show that DFN simulations provide results that are qualitatively similar to results from ECPM calculations. However, because the ECPM is a less direct approach, notable differences exist when compared to the DFN approach.

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Bonanno, Enrico, Günter Blöschl e Julian Klaus. "Exploring tracer information in a small stream to improve parameter identifiability and enhance the process interpretation in transient storage models". Hydrology and Earth System Sciences 26, n. 23 (2 dicembre 2022): 6003–28. http://dx.doi.org/10.5194/hess-26-6003-2022.

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Abstract. The transport of solutes in river networks is controlled by the interplay of processes such as in-stream solute transport and the exchange of water between the stream channel and dead zones, in-stream sediments, and adjacent groundwater bodies. Transient storage models (TSMs) are a powerful tool for testing hypotheses related to solute transport in streams. However, model parameters often do not show a univocal increase in model performances in a certain parameter range (i.e. they are non-identifiable), leading to an unclear understanding of the processes controlling solute transport in streams. In this study, we increased parameter identifiability in a set of tracer breakthrough experiments by combining global identifiability analysis and dynamic identifiability analysis in an iterative approach. We compared our results to inverse modelling approaches (OTIS-P) and the commonly used random sampling approach for TSMs (OTIS-MCAT). Compared to OTIS-P, our results informed about the identifiability of model parameters in the entire feasible parameter range. Our approach clearly improved parameter identifiability compared to the standard OTIS-MCAT application, due to the progressive reduction of the investigated parameter range with model iteration. Non-identifiable results led to solute retention times in the storage zone and the exchange flow with the storage zone with differences of up to 4 and 2 orders of magnitude compared to results with identifiable model parameters respectively. The clear differences in the transport metrics between results obtained from our proposed approach and results from the classic random sampling approach also resulted in contrasting interpretations of the hydrologic processes controlling solute transport in a headwater stream in western Luxembourg. Thus, our outcomes point to the risks of interpreting TSM results when even one of the model parameters is non-identifiable. Our results showed that coupling global identifiability analysis with dynamic identifiability analysis in an iterative approach clearly increased parameter identifiability in random sampling approaches for TSMs. Compared to the commonly used random sampling approach and inverse modelling results, our analysis was effective at obtaining higher accuracy of the evaluated solute transport metrics, which is advancing our understanding of hydrological processes that control in-stream solute transport.

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4

Van Rooy, Dirk. "Stochastic Modelling of a Contaminated Aquifer". Hydrology Research 17, n. 4-5 (1 agosto 1986): 315–24. http://dx.doi.org/10.2166/nh.1986.0023.

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A stochastic solute transport model is applied to a groundwater contamination case. The contamination is caused by leachate from an unprotected landfill situated in a highly-permeable unconfined aquifer. The stochastic model combines the geostatistical techniques of semivariogram analysis and kriging with a numerical solute transport model. A Monte Carlo approach that utilizes the turning bands technique to genereate transmissivity fields is used. Here some preliminary results of the unconditional stochastic simulations are presented. The contaminant plume is characterized by expected concentrations of chloride and standard deviations.

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Li, L., D. A. Barry e K. J. L. Stone. "Centrifugal modelling of nonsorbing, nonequilibrium solute transport in a locally inhomogeneous soil". Canadian Geotechnical Journal 31, n. 4 (1 agosto 1994): 471–77. http://dx.doi.org/10.1139/t94-056.

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This paper presents results of centrifugal modelling of physical nonequilibrium transport of nonsorbing solute in a locally inhomogeneous soil. Mathematical modelling of this class of transport process is restricted by the difficulties in determining the model parameters. The modelling results suggest that physical modelling on a geotechnical centrifuge may offer another approach to tackle this problem under certain conditions. Key words : tracer transport, centrifuge, physical modelling, heterogeneous soil, two-region model, scaling.

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6

., A. A. Siyal, A. G. Siyal . e Z. A. Abro . "Modelling of Solute Transport from Single Soil Aggregate". Journal of Applied Sciences 2, n. 4 (15 marzo 2002): 470–73. http://dx.doi.org/10.3923/jas.2002.470.473.

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7

GEENS, J., K. BOUSSU, C. VANDECASTEELE e B. VANDERBRUGGEN. "Modelling of solute transport in non-aqueous nanofiltration". Journal of Membrane Science 281, n. 1-2 (15 settembre 2006): 139–48. http://dx.doi.org/10.1016/j.memsci.2006.03.028.

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8

Kulasekera, Priyantha B., e Gary W. Parkin. "Influence of the shape of inter-horizon boundary and size of soil tongues on preferential flow under shallow groundwater conditions: A simulation study". Canadian Journal of Soil Science 91, n. 2 (maggio 2011): 211–21. http://dx.doi.org/10.4141/cjss10079.

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Kulasekera, P. B. and Parkin, G. W. 2011. Influence of the shape of inter-horizon boundary and size of soil tongues on preferential flow under shallow groundwater conditions: A simulation study. Can. J. Soil Sci. 91: 211–221. Detailed studies of the impact of soil tongues at soil horizon interfaces are very important in understanding preferential flow processes through layered soils and in improving the accuracy of models predicting water and solute transport through the vadose zone. The implication of having soil tongues of different shapes and sizes created at the soil horizon interface on solute transport through a layered soil horizon was studied by simulating water and solute transport using the VS2DI model. This 2-D simulation study reconfirmed that soil tongues facilitate preferential flow, and the level of activeness of tongues may depend on the number of soil tongues, their spacing and distribution. Also, the size of the soil tongues (length and diameter at the interface between the soil horizons) and their shape influence the rate of preferential flow. Increasing tongue length consistently resulted in an increase in solute velocity across the entire soil profile regardless of the tongue shape; for example, a soil tongue of 0.25 m length increased solute velocity by about 1.5 times over a soil profile without tongues, but this increase might be different for soil types and groundwater conditions other than those considered in this study. Narrowing of tongues increased solute velocity, whereas increasing the number of tongues in a wider soil profile decreased the solute-front's velocity. As tongue length increased, the area containing solutes at prescribed elapsed times decreased. An implication of this study is that soil horizon tongue shape and spacing reduce pollutant residence times, hence inter-horizon boundary morphology should be considered when modelling transport through the vadose zone. As well, since the solute velocity behaviours of a triangular- and a wider rectangular-shaped tongue were nearly identical, simply measuring solute velocity in the field will reveal little information on the shape of a soil tongue.

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9

Moradi, G., e B. Mehdinejadiani. "Modelling solute transport in homogeneous and heterogeneous porous media using spatial fractional advection-dispersion equation". Soil and Water Research 13, No. 1 (24 gennaio 2018): 18–28. http://dx.doi.org/10.17221/245/2016-swr.

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This paper compared the abilities of advection-dispersion equation (ADE) and spatial fractional advection-dispersion equation (sFADE) to describe the migration of a non-reactive contaminant in homogeneous and heterogeneous soils. To this end, laboratory tests were conducted in a sandbox sizing 2.5 × 0.1 × 0.6 m (length × width × height). After performing a parametric sensitivity analysis, parameters of sFADE and ADE were individually estimated using the inverse problem method at each distance. The dependency of estimated parameters on distance was examined. The estimated parameters at 30 cm were used to predict breakthrough curves (BTCs) at subsequent distances. The results of sensitivity analysis indicated that average pore-water velocity and dispersion coefficient were, respectively, the most and least sensitive parameters in both mathematical models. The values of fractional differentiation orders (α) for sFADE were smaller than 2 in both soils. The scale-dependency of the dispersion coefficients of ADE and sFADE was observed in both soils. However, the application of sFADE to describe solute transport reduced the scale effect on the dispersion coefficient, especially in the heterogeneous soil. For the homogeneous soil, the predicting results of ADE and sFADE were nearly similar, while for the heterogeneous soil, the predicting results of sFADE were more satisfactory in comparison with those of ADE, especially when the transport distance increased. Compared to ADE, the sFADE simulated somewhat better the tailing parts of BTCs and showed the earlier arrival of tracer. Overall, the solute transport, especially in the heterogeneous soil, was non-Fickian and the sFADE somewhat better described non-Fickian transport.

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Sternagel, Alexander, Ralf Loritz, Wolfgang Wilcke e Erwin Zehe. "Simulating preferential soil water flow and tracer transport using the Lagrangian Soil Water and Solute Transport Model". Hydrology and Earth System Sciences 23, n. 10 (22 ottobre 2019): 4249–67. http://dx.doi.org/10.5194/hess-23-4249-2019.

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Abstract. We propose an alternative model concept to represent rainfall-driven soil water dynamics and especially preferential water flow and solute transport in the vadose zone. Our LAST-Model (Lagrangian Soil Water and Solute Transport) is based on a Lagrangian perspective of the movement of water particles (Zehe and Jackisch, 2016) carrying a solute mass through the subsurface which is separated into a soil matrix domain and a preferential flow domain. The preferential flow domain relies on observable field data like the average number of macropores of a given diameter, their hydraulic properties and their vertical length distribution. These data may be derived either from field observations or by inverse modelling using tracer data. Parameterization of the soil matrix domain requires soil hydraulic functions which determine the parameters of the water particle movement and particularly the distribution of flow velocities in different pore sizes. Infiltration into the matrix and the macropores depends on their respective moisture state, and subsequently macropores are gradually filled. Macropores and matrix interact through diffusive mixing of water and solutes between the two flow domains, which again depends on their water content and matric potential at the considered depths. The LAST-Model is evaluated using tracer profiles and macropore data obtained at four different study sites in the Weiherbach catchment in southern Germany and additionally compared against simulations using HYDRUS 1-D as a benchmark model. While both models show qual performance at two matrix-flow-dominated sites, simulations with LAST are in better accordance with the fingerprints of preferential flow at the two other sites compared to HYDRUS 1-D. These findings generally corroborate the feasibility of the model concept and particularly the implemented representation of macropore flow and macropore–matrix exchange. We thus conclude that the LAST-Model approach provides a useful and alternative framework for (a) simulating rainfall-driven soil water and solute dynamics and fingerprints of preferential flow as well as (b) linking model approaches and field experiments. We also suggest that the Lagrangian perspective offers promising opportunities to quantify water ages and to evaluate travel and residence times of water and solutes by a simple age tagging of particles entering and leaving the model domain.

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11

Lau, S. D., V. R. Stovin e I. Guymer. "The prediction of solute transport in surcharged manholes using CFD". Water Science and Technology 55, n. 4 (1 febbraio 2007): 57–64. http://dx.doi.org/10.2166/wst.2007.095.

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Solute transport processes occur within a wide range of water engineering structures, and urban drainage engineers increasingly rely on modelling tools to represent the transport of dissolved materials. The models take as input representative travel time and dispersion characteristics for key system components, and these generally have to be identified via field or laboratory measurements. Computational Fluid Dynamics (CFD) has the potential to reveal the underlying hydraulic processes that control solute transport, and to provide a generic means of identifying relevant parameter values. This paper reports on a study that has been undertaken to evaluate the feasibility of utilising a CFD-based approach to modelling solute transport. Discrete phase modelling has been adopted, as this is computationally efficient and robust when compared with the time-dependent solution of the advection–dispersion equation. Simulation results are compared with published laboratory data characterising the dispersion effects of surcharged manholes, focusing specifically on an 800 mm diameter laboratory manhole for a flowrate of 0.002 m3/s and a range of surcharge depths. Preliminary indications are that the CFD results adequately replicate the measured downstream temporal concentration profiles, and that a threshold surcharge depth, corresponding to a change in hydraulic regime within the manhole, can also be identified.

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Liang, Jie, Guangming Zeng, Shenglian Guo, Anlei Wei, Xiaodong Li, Lin Shi e Chunyan Du. "Optimal solute transport in heterogeneous aquifer: coupled inverse modelling". International Journal of Environment and Pollution 42, n. 1/2/3 (2010): 258. http://dx.doi.org/10.1504/ijep.2010.034243.

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13

Lin, B., e K. Shiono. "Numerical modelling of solute transport in compound channel flows". Journal of Hydraulic Research 33, n. 6 (novembre 1995): 773–88. http://dx.doi.org/10.1080/00221689509498551.

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14

Griffioen, J. W., e D. A. Barry. "Centrifuge modelling of solute transport during partially saturated flow". Environmental Modelling & Software 14, n. 2-3 (dicembre 1998): 191–201. http://dx.doi.org/10.1016/s1364-8152(98)00070-x.

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15

Carrera, Jesús. "An overview of uncertainties in modelling groundwater solute transport". Journal of Contaminant Hydrology 13, n. 1-4 (giugno 1993): 23–48. http://dx.doi.org/10.1016/0169-7722(93)90049-x.

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16

Santos, J. L. C., A. H. Montesinos, A. Karpinsky, S. Velizarov e J. G. Crespo. "Modelling of solute and solvent transport through nanofiltration membranes". Desalination 199, n. 1-3 (novembre 2006): 448–50. http://dx.doi.org/10.1016/j.desal.2006.03.102.

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17

Waniewski, Jacek, Stefan Antosiewicz, Daniel Baczynski, Jan Poleszczuk, Mauro Pietribiasi, Bengt Lindholm e Zofia Wankowicz. "Peritoneal Fluid Transport rather than Peritoneal Solute Transport Associates with Dialysis Vintage and Age of Peritoneal Dialysis Patients". Computational and Mathematical Methods in Medicine 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/8204294.

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During peritoneal dialysis (PD), the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21–87) years; median time on PD 19 (3–100) months) underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS), fraction of ultrasmall pores (αu), osmotic conductance for glucose (OCG), and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters). Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage,αuwas higher. Thus, fluid transport parameters—rather than solute transport parameters—are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane.

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18

Young, G. W. "Float Zone Modelling: Transport Phenomena and Morphological Stability". Applied Mechanics Reviews 43, n. 5S (1 maggio 1990): S63—S69. http://dx.doi.org/10.1115/1.3120853.

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A model is presented for a float zone established in a vertical sheet. Heat transfer between the system (melt, feed and crystal) and the surrounding environment (including the heating source) is assumed to take place via radiation. Asymptotic solutions for the temperature, concentration, and melt flow profiles and the melting, solidifying and melt/gas interfacial shapes are developed in the limit of small aspect ratio (zone half-width/length) and weak surface tension driven flows. We find that convective heat transport leads to melt back of the solidification front near the edges. Further, lateral solute segregation is due to both convective effects and curved solidification fronts. Increasing the flow or increasing the velocity of solidification leads to increased lateral solute segregation in melts that are not well mixed. Hence, flat solidification fronts may not yield flat concentration profiles. To reduce the level of convection, hot wall, low temperature gradient float zone techniques are also investigated. Morphological stability of the solidification front is of concern for such heating configurations. We present the results of a linear stability analysis in the limits of small segregation coefficient, slow velocities of solidification, and large surface heat transfer. It is found that shorter melt zones are less susceptible to long wavelength morphological instabilities.

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Guymer, I., e R. Dutton. "Application of transient storage modelling to solute transport across a surcharged manhole". Water Science and Technology 55, n. 4 (1 febbraio 2007): 65–73. http://dx.doi.org/10.2166/wst.2007.096.

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Results from previous solute tracer laboratory experiments across circular surcharged manhole structures by Guymer et al. have been used to optimise parameters within Hart's transient storage model (TSM). A surcharge threshold level for the model parameters is evident and this is explained in relation to jet theory. The ability to decompose the TSM is demonstrated with reference to frequency of exchange with the storage zone allowing the proportions of solute entering these regions to be inferred, together with an indication of storage volume retention times.

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Mojid, M. A., e H. Vereecken. "Modelling velocity and retardation factor of a nonlinearly sorbing solute plume". Soil Research 43, n. 6 (2005): 735. http://dx.doi.org/10.1071/sr04111.

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This study, considering evidences of slower sorption rates of reactive solutes in the field than in laboratory, quantifies the velocity and retardation factor of a sodium fluorescein (uranin: C20H10Na2O5) plume over its travel path in a heterogeneous aquifer. The transport process of uranin was evaluated by batch experiments and from breakthrough curves (BTCs) by using solute-transport models. Method of time moments analysed BTCs of uranin and bromide to derive the velocity and retardation factor. A constant velocity of the bromide plume, 0.64 m/day, implies a spatially and temporally uniform velocity field where groundwater flows at steady-state condition. A large dimensionless index (195) of chemical non-equilibrium model and equilibrium distribution coefficient (0.32) of uranin are indicative of chemical non-equilibrium transport process. The travel time of uranin plume increases asymptotically, following power law, with travel path of the plume. Good agreement of the exponent of power law with that of Freundlich isotherm is a result of nonlinear sorption, and provides an independent way of estimating the exponent of the isotherm. The local velocity of the plume decreases asymptotically in time and is predicted by the derivative of the relationship between travel path and travel time of the plume. The retardation factor, which increases in time following power law, when estimated from the local velocity, is considerably larger than that estimated from travel time of the plume.

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Purnaditya, Ngakan Putu, Herr Soeryantono e Dwinanti Rika Marthanty. "Proposing mathematical model for seawater intrusion phenomena in the coastal aquifer". MATEC Web of Conferences 197 (2018): 10003. http://dx.doi.org/10.1051/matecconf/201819710003.

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Seawater intrusion is one of groundwater quality problem which in this problem, the mixing between freshwater and saltwater in the coastal aquifer occurs. Mathematical modelling can be formulated to describe the mechanism of this phenomena. The main objective of this research is to develop the mathematical model of groundwater flow and solute transport that applicable to seawater intrusion mechanism. This mechanism is arranged as a differential equation and distinguished into 3 equations. The first equation is groundwater flow equation in dependent-density. It means that the density of groundwater (ρ) changes in spatial and temporal domain due freshwater and seawater are mixed in the coastal aquifer. The second equation is solute transport. Like as groundwater flow equation, in solute transport equation there is a change of solute concentration (С) in the spatial and temporal domain. The last equation is the relationship between groundwater density (ρ) and solute concentration (С). Special case for the third equation, in which this equation is adopted from USGS Seawat model. The first equation and second equation are governed by Eulerian mass conservation law. The main theoretical consideration of governing groundwater flow equation is such as fluid and porous matrix compressibility theory, Darcy's law for groundwater in motion theory and some properties of soil. In other hands, solute transport is involving advection transport and hydrodynamic dispersion transport. Hydrodynamic dispersion is arranged by diffusion Fick's law and dispersion in porous media theory and it depends on transversal and longitudinal dispersivity. Using Jacob Bear's theory which states that fluid density as temperature, concentration and pressure function, authors obtain three primary variables in this model. Those variables follow fluid density (ρ), total head (h) and concentration (С). In this model, isotropic and isobar condition is considered, hence fluid density (ρ) is a function of concentration (С) only. Finally, from this research, authors wish this mathematical model is applicable to modelling, describing and predicting seawater intrusion phenomena theoretically.

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Karmakar, Shyamal, Alexandru Tatomir, Sandra Oehlmann, Markus Giese e Martin Sauter. "Numerical Benchmark Studies on Flow and Solute Transport in Geological Reservoirs". Water 14, n. 8 (17 aprile 2022): 1310. http://dx.doi.org/10.3390/w14081310.

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Predicting and characterising groundwater flow and solute transport in engineering and hydrogeological applications, such as dimensioning tracer experiments, rely primarily on numerical modelling techniques. During software selection for numerical modelling, the accuracy of the results, financial costs of the simulation software, and computational resources should be considered. This study evaluates numerical modelling approaches and outlines the advantages and disadvantages of several simulators in terms of predictability, temporal control, and computational efficiency conducted in a single user and single computational resource set-up. A set of well-established flow and transport modelling simulators, such as MODFLOW/MT3DMS, FEFLOW, COMSOL Multiphysics, and DuMuX were tested and compared. These numerical simulators are based on three numerical discretisation schemes, i.e., finite difference (FD), finite element (FE), and finite volume (FV). The influence of dispersivity, potentially an artefact of numerical modelling (numerical dispersion), was investigated in parametric studies, and results are compared with analytical solutions. At the same time, relative errors were assessed for a complex field scale example. This comparative study reveals that the FE-based simulators COMSOL and FEFLOW show higher accuracy for a specific range of dispersivities under forced gradient conditions than DuMuX and MODFLOW/MT3DMS. FEFLOW performs better than COMSOL in regard to computational time both in single-core and multi-core computing. Overall computational time is lowest for the FD-based simulator MODFLOW/MT3DMS while the number of mesh elements is low (here < 12,800 elements). However, for finer discretisation, FE software FEFLOW performs faster.

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Tian, Tianhai, Kevin Burrage e Ray Volker. "Stochastic modelling and simulations for solute transport in porous media". ANZIAM Journal 45 (29 giugno 2004): 551. http://dx.doi.org/10.21914/anziamj.v45i0.907.

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Li, C. W. "Modelling variably saturated flow and solute transport into sandy soil". Journal of Hydrology 186, n. 1-4 (novembre 1996): 315–25. http://dx.doi.org/10.1016/s0022-1694(96)03024-7.

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PUNT, A., G. MILLWARD e J. HARRIS. "Modelling solute transport in the Tweed Estuary, UK using ECoS". Science of The Total Environment 314-316 (1 ottobre 2003): 715–25. http://dx.doi.org/10.1016/s0048-9697(03)00079-2.

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Grassi, Mario, Soon Hong Yuk e Sun Hang Cho. "Modelling of solute transport across a temperature-sensitive polymer membrane". Journal of Membrane Science 152, n. 2 (gennaio 1999): 241–49. http://dx.doi.org/10.1016/s0376-7388(98)00223-3.

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Kurotori, Takeshi, Christopher Zahasky, Sayed Alireza Hosseinzadeh Hejazi, Saurabh M. Shah, Sally M. Benson e Ronny Pini. "Measuring, imaging and modelling solute transport in a microporous limestone". Chemical Engineering Science 196 (marzo 2019): 366–83. http://dx.doi.org/10.1016/j.ces.2018.11.001.

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Martinac, Adam D., e Lynne E. Bilston. "Computational modelling of fluid and solute transport in the brain". Biomechanics and Modeling in Mechanobiology 19, n. 3 (13 novembre 2019): 781–800. http://dx.doi.org/10.1007/s10237-019-01253-y.

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Jim Yeh, T. C. "Stochastic modelling of groundwater flow and solute transport in aquifers". Hydrological Processes 6, n. 4 (ottobre 1992): 369–95. http://dx.doi.org/10.1002/hyp.3360060402.

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Tucker, Amy, Delphis F. Levia, Gabriel G. Katul, Kazuki Nanko e Louis F. Rossi. "A network model for stemflow solute transport". Applied Mathematical Modelling 88 (dicembre 2020): 266–82. http://dx.doi.org/10.1016/j.apm.2020.06.047.

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Kumar, Manoj, e Anunay Gour. "Novel Approach to Groundwater Contaminant Transport Modelling". Journal of University of Shanghai for Science and Technology 23, n. 07 (5 luglio 2021): 281–92. http://dx.doi.org/10.51201/jusst/21/07132.

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Abstract (sommario):

This paper comprehensively investigates literature about modelling techniques used in groundwater contaminant transport modelling. Modelling of groundwater is a useful way for the management of groundwater resources, also assessing the fate of contaminants and their remediation. Models very conveniently help to study complex real conditions and examine specific phenomena in addition to predicting the future behaviour of any problem. The use of groundwater simulation programming tools such as MODFLOW, MT3DMS, RT3D, FEFLOW, and MODPATH to model multi-directional contamination transport yields accurate results. Movement, storage, and change of solute concentration are largely regulated by groundwater flow gradient. As a result, a precise description of the flow mechanism is very important. If models are not properly constructed and interpreted, they can become complicated and may generate wide errors. Well-defined and clear modelling objectives produce suitable models for efficient error-free modelling processes. The study will assist modellers to clearly define their model objective and select appropriate modelling tools.

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32

Miron, Simona M., Patrick Dutournié e Arnaud Ponche. "Filtration of Uncharged Solutes: An Assessment of Steric Effect by Transport and Adsorption Modelling". Water 11, n. 10 (19 ottobre 2019): 2173. http://dx.doi.org/10.3390/w11102173.

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The major aim of this work was to understand and estimate the evolution of the membrane selectivity of neutral solutes after the filtration of protein or amino acid solutions. Classical methodologies led to the estimation of the mean pore radius, different for each filtrated neutral solute. The use of pore size distribution from nitrogen adsorption/desorption experiments enabled a good description of hydraulic and selectivity performances. The modification of the membrane hydraulic properties after the successive filtration of protein solutions revealed that the decrease is quasi linear, the same for all the studied membranes and independent of prior tests. According to the experimental observations, an adsorption model was developed, considering a layer by layer adsorption in the larger pores of the membrane. The predictive obtained results are in good agreement with the experimental rejection rates, validating the assumptions.

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33

Broshears, Robert E. "Reactive solute transport in acidic streams". Water, Air, & Soil Pollution 90, n. 1-2 (luglio 1996): 195–204. http://dx.doi.org/10.1007/bf00619281.

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34

Sheppard, Marsha I., e S. C. Sheppard. "A soil solute transport model evaluated on two experimental systems". Ecological Modelling 37, n. 3-4 (luglio 1987): 191–206. http://dx.doi.org/10.1016/0304-3800(87)90025-1.

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35

Beg, Md, Matteo Rubinato, Rita Carvalho e James Shucksmith. "CFD Modelling of the Transport of Soluble Pollutants from Sewer Networks to Surface Flows during Urban Flood Events". Water 12, n. 9 (9 settembre 2020): 2514. http://dx.doi.org/10.3390/w12092514.

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Abstract (sommario):

Surcharging urban drainage systems are a potential source of pathogenic contamination of floodwater. While a number of previous studies have investigated net sewer to surface hydraulic flow rates through manholes and gullies during flood events, an understanding of how pollutants move from sewer networks to surface flood water is currently lacking. This paper presents a 3D CFD model to quantify flow and solute mass exchange through hydraulic structures featuring complex interacting pipe and surface flows commonly associated with urban flood events. The model is compared against experimental datasets from a large-scale physical model designed to study pipe/surface interactions during flood simulations. Results show that the CFD model accurately describes pipe to surface flow partition and solute transport processes through the manhole in the experimental setup. After validation, the model is used to elucidate key timescales which describe mass flow rates entering surface flows from pipe networks. Numerical experiments show that following arrival of a well-mixed solute at the exchange structure, solute mass exchange to the surface grows asymptotically to a value equivalent to the ratio of flow partition, with associated timescales a function of the flow conditions and diffusive transport inside the manhole.

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36

Qian, Qin, Vaughan Voller e Heinz G. Stefan. "Modeling of solute transport into sub-aqueous sediments". Applied Mathematical Modelling 31, n. 8 (agosto 2007): 1461–78. http://dx.doi.org/10.1016/j.apm.2006.09.001.

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37

Feddes, R. A., e J. C. van Dam. "MODELLING WATER FLOW AND SOLUTE TRANSPORT FOR HORTICULTURAL AND ENVIRONMENTAL MANAGEMENT". Acta Horticulturae, n. 573 (marzo 2002): 107–17. http://dx.doi.org/10.17660/actahortic.2002.573.13.

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38

Voller, V. R., A. D. Brent e C. Prakash. "The modelling of heat, mass and solute transport in solidification systems". International Journal of Heat and Mass Transfer 32, n. 9 (settembre 1989): 1719–31. http://dx.doi.org/10.1016/0017-9310(89)90054-9.

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39

Mustafa, Shaymaa, Arifah Bahar, Zainal Abdul Aziz e Mohamad Darwish. "Solute transport modelling to manage groundwater pollution from surface water resources". Journal of Contaminant Hydrology 233 (agosto 2020): 103662. http://dx.doi.org/10.1016/j.jconhyd.2020.103662.

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40

Selim, Tarek, Magnus Persson e Jonas Olsson. "Impact of spatial rainfall resolution on point-source solute transport modelling". Hydrological Sciences Journal 62, n. 16 (23 novembre 2017): 2587–96. http://dx.doi.org/10.1080/02626667.2017.1403029.

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41

Hariharan, D., e N. A. Peppas. "Modelling of water transport and solute release in physiologically sensitive gels". Journal of Controlled Release 23, n. 2 (febbraio 1993): 123–35. http://dx.doi.org/10.1016/0168-3659(93)90038-7.

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42

Peng, Y., J. G. Zhou e R. Burrows. "Modelling solute transport in shallow water with the lattice Boltzmann method". Computers & Fluids 50, n. 1 (novembre 2011): 181–88. http://dx.doi.org/10.1016/j.compfluid.2011.07.008.

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43

Bogena, Heye R., e Bernd Diekkrüger. "Modelling solute and sediment transport at different spatial and temporal scales". Earth Surface Processes and Landforms 27, n. 13 (dicembre 2002): 1475–89. http://dx.doi.org/10.1002/esp.442.

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44

Nakagawa, K., T. Hosokawa, S. I. Wada, K. Momii, K. Jinno e R. Berndtsson. "Modelling reactive solute transport from groundwater to soil surface under evaporation". Hydrological Processes 24, n. 5 (28 febbraio 2010): 608–17. http://dx.doi.org/10.1002/hyp.7555.

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45

Ma, Hai Yi, Shu Ping Yi, Guo Cheng Ren e Xue Ling Hu. "Analysis of Uncertainties Affecting Numerical Transport Models for a Potential Radioactive Waste Disposal Site". Advanced Materials Research 955-959 (giugno 2014): 1607–14. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1607.

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Abstract (sommario):

Numerical models have been commonly used to study solute transport behaviours both in laboratory-and field-scale cases. However, numerical interpretation and predictions of solute transport are complicated by various uncertainties and therefore can be misleading and lead to incorrect understanding of solute transport behaviours in hydrogeological systems. Such uncertainties have been discussed with a case study of radionuclides transport at a potential site for disposal of Low-and Intermediate-Level radioactive Wastes (LILW) in southern China. Firstly, pre-modelling assumptions cause uncertainties for model performance and have a significant influence on the model output. Therefore, such assumptions and related factors should be thoroughly considered and minimized in laboratory experiments or investigated in the field. Secondly, difference in the calculated plumes caused by uncertainties in the development of conceptual models suggests that the hydrogeological conceptual model should be developed based on intrinsic understanding of the transport problems and relevant data collection. Thirdly, relative sensitivity (RS) has been calculated to analyse the parameter uncertainties. Results indicate that the uncertainties are tracer-, parameter-and time-dependent. Therefore, model uncertainties arising from parameters should be considered for each specific parameter with the specific period. Finally, prediction scenarios are associated with uncertainties in the model prediction stage. Results suggest that the uncertainties in scenarios of future transport conditions should be recognized prior to model prediction. This study illustrates some of the uncertainties that might affect numerical transport models and therefore will be a useful reference for application of solute transport models to assessment of contamination risks from a LILW disposal site.

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46

Mitchell, R. J. "Matrix suction and diffusive transport in centrifuge models". Canadian Geotechnical Journal 31, n. 3 (1 giugno 1994): 357–63. http://dx.doi.org/10.1139/t94-043.

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Abstract (sommario):

Centrifuge modelling of the lateral spread of a conservative solute in a partly saturated fine sand has been accomplished in a 3 m radius centrifuge at simulated gravitational accelerations of 25 and 50 g. The distributions of the contaminant after 2 months, 6 months, and 1 year of prototype time were found experimentally by dissection of models. The results support the contention that centrifuge modelling does correctly recreate prototype transport phenomena, including transport due to matrix suction, in partly saturated fine sand. For the conditions modelled, it was found that all of the contaminant introduced at the soil surface became immobilized, for at least 1 year, inthe upper 2–3 m of the 6 m deep soil profile. Key words : centrifuge modelling, contaminant fate, vadoze zone, matrix suction, diffusion.

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47

Høgh Jensen, K., e J. C. Refsgaard. "Spatial Variability of Physical Parameters and Processes in Two Field Soils". Hydrology Research 22, n. 5 (1 ottobre 1991): 275–302. http://dx.doi.org/10.2166/nh.1991.0020.

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Abstract (sommario):

Natural field systems exhibit a large degree of soil heterogeneity which affects the movement of water and solutes and thus leads to highly varying observations of water content and solute concentration. To investigate this problem comprehensive field investigation programs were carried out at two field sites in Denmark representing two different soil types, a coarse sand and a sandy loam, respectively. The field investigations included collection of soil samples for analysis of textural composition, retention, and hydraulic conductivity, measurements of water content and suction, and measurements of radioactive tracer concentration, all carried out at a number of positions within the two field sites. Models for one-dimensional vertical unsaturated flow and solute transport were applied to the two field sites, and the simulation results were compared to field measurements of water content, suction and solute concentration. This paper describes results from model simulations in individual soil profiles, while the variability issues at field scale are described in the two accompanying papers. The modelling approach was based on numerical solutions to Richards' equation for water flow and the convection-dispersion equation (CDE) for solute transport. The model results from the coarse sand field site compared relatively well to measurements of water content, suction, and concentration except for the upper soil layer (∼ 10 cm depth) where the measured water contents appeared to be somewhat uncertain. Due to the neglecting of hysteresis and macropore flow (by-pass) in the model the measured retention curves (drainage based) and the hydraulic conductivity functions at the sandy loam field site had to he modified empirically through the calibration procedure in order to match the measurements.

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48

Kirkham, James M., Christopher J. Smith, Richard B. Doyle e Philip H. Brown. "Inverse modelling for predicting both water and nitrate movement in a structured-clay soil (Red Ferrosol)". PeerJ 6 (16 gennaio 2019): e6002. http://dx.doi.org/10.7717/peerj.6002.

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Abstract (sommario):

Soil physical parameter calculation by inverse modelling provides an indirect way of estimating the unsaturated hydraulic properties of soils. However many measurements are needed to provide sufficient data to determine unknown parameters. The objective of this research was to assess the use of unsaturated water flow and solute transport experiments, in horizontal packed soil columns, to estimate the parameters that govern water flow and solute transport. The derived parameters are then used to predict water infiltration and solute migration in a repacked soil wedge. Horizontal columns packed with Red Ferrosol were used in a nitrate diffusion experiment to estimate either three or six parameters of the van Genuchten–Mualem equation while keeping residual and saturated water content, and saturated hydraulic conductivity fixed to independently measured values. These parameters were calculated using the inverse optimisation routines in Hydrus 1D. Nitrate concentrations measured along the horizontal soil columns were used to independently determine the Langmuir adsorption isotherm. The soil hydraulic properties described by the van Genuchten–Mualem equation, and the NO3–adsorption isotherm, were then used to predict water and NO3–distributions from a point-source in two 3D flow scenarios. The use of horizontal columns of repacked soil and inverse modelling to quantify the soil water retention curve was found to be a simple and effective method for determining soil hydraulic properties of Red Ferrosols. These generated parameters supported subsequent testing of interactive flow and reactive transport processes under dynamic flow conditions.

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49

Sookhak Lari, Kaveh, e Dirk Mallants. "Coupled Heat-Mass Transport Modelling of Radionuclide Migration from a Nuclear Waste Disposal Borehole". Geofluids 2022 (4 aprile 2022): 1–23. http://dx.doi.org/10.1155/2022/5264257.

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Abstract (sommario):

Disposal of radioactive waste originating from reprocessing of spent research reactor fuel typically includes stainless steel canisters with waste immobilised in a glass matrix. In a deep borehole disposal concept, waste packages could be stacked in a disposal zone at a depth of one to potentially several kilometres. This waste will generate heat for several hundreds of years. The influence of combining a natural geothermal gradient with heat from decaying nuclear waste on radionuclide transport from deep disposal boreholes is studied by implementing a coupled heat-solute mass transport modelling framework, subjected to depth-dependent temperature, pressure, and viscosity profiles. Several scenarios of waste-driven heat loads were investigated to test to what degree, if any, the additional heat affects radionuclide migration by generating convection-driven transport. Results show that the heat output and the calculated radioactivity at a hypothetical near-surface observation point are directly correlated; however, the overall impact of convection-driven transport is small due to the short duration (a few hundred years) of the heat load. Results further showed that the calculated radiation dose at the observation point was very sensitive to the magnitude of the effective diffusion parameter of the host rock. Coupled heat-solute mass transport models are necessary tools to identify influential processes regarding deep borehole disposal of heat-generating long-lived radioactive waste.

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50

Stachowska-Pietka, Joanna, Jan Poleszczuk, Michael F. Flessner, Bengt Lindholm e Jacek Waniewski. "Alterations of peritoneal transport characteristics in dialysis patients with ultrafiltration failure: tissue and capillary components". Nephrology Dialysis Transplantation 34, n. 5 (6 novembre 2018): 864–70. http://dx.doi.org/10.1093/ndt/gfy313.

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Abstract (sommario):

AbstractBackgroundUltrafiltration failure (UFF) in peritoneal dialysis (PD) patients is due to altered peritoneal transport properties leading to reduced capacity to remove excess water. Here, with the aim to establish the role of local alterations of the two major transport barriers, peritoneal tissue and capillary wall, we investigate changes in overall peritoneal transport characteristics in UFF patients in relation to corresponding local alterations of peritoneal tissue and capillary wall transport properties.MethodsSix-hour dwell studies using 3.86% glucose solutions and radioisotopically labelled serum albumin added to dialysate as a volume marker were analysed in 31 continuous ambulatory PD patients, 20 with normal ultrafiltration (NUF) and 11 with UFF. For each patient, the physiologically based parameters were evaluated for both transport barriers using the spatially distributed approach based on the individual intraperitoneal profiles of volume and concentrations of glucose, sodium, urea and creatinine.ResultsUFF patients as compared with NUF patients had increased solute diffusivity in both barriers, peritoneal tissue and capillary wall, decreased tissue hydraulic conductivity and increased local lymphatic absorption and functional decrease in the fraction of the ultra-small pores. This resulted in altered distribution of fluid and solutes in the peritoneal tissue, and decreased penetration depths of fluid and solutes into the tissue in UFF patients.ConclusionsMathematical modelling using a spatially distributed approach for the description of clinical data suggests that alterations both in the capillary wall and in the tissue barrier contribute to UFF through their effect on transport and distribution of solutes and fluid within the tissue.

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