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solute transport characteristics of a deep soil profile in the Loess Plateau,China

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Journal of Arid Land 2018年第4期10卷 628-637页

作者： WANG Jiao SHAO Ming'an Key Laboratory of Ecosystems Network Observation and Modeling Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F UniversityYangling 712100China

Understanding solute transport behaviors of deep soil profile in the Loess Plateau is helpful for ecological construction and agricultural production improvement. In this study, solute transport processes of a deep soil profile were measured by a conservative tracer experiment using 25 undisturbed soil cores （20 cm long and 7 cm diameter for each） continuously sampled from the surface downward to the depth of 500 cm in the Loess Plateau of China. The solute transport breakthrough curves （BTCs） were analyzed in terms of the convection-dispersion equation （CDE） and the mobile-immobile model （MIM）. Average pore-water velocity and dispersion coefficient （or effective dispersion coefficient） were calculated using the CDE and MIM. Basic soil properties and water infiltration parameters were also determined to explore their influence on the solute transport parameters. Both pore-water velocity and dispersion coefficient （or effective dispersion coefficient） generally decreased with increasing depth, and the dispersivity fluctuated along the soil profile. There was a good linear correlation between log-transformed pore-water velocity and dispersion coefficient, with a slope of about 1.0 and an average dispersivity of 0.25 for the entire soil profile. Generally speaking, the soil was more homogeneous along the soil profile. Our results also show that hydrodynamic dispersion is the dominant mechanism of solute transport of loess soils in the study area.

关键词： solute transport loess soil pore-water velocity dispersion coefficient hydraulic conductivity Loess Plateau

solute transport and geochemical modeling of the coastal quaternary aquifer, Delta Dahab Basin, South Sinai, Egypt

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Acta Geochimica 2024年第1期43卷 16-39页

作者： Amira Samy Mustafa Eissa Seham Shahen Moustafa M.Said Rabab M.Abou-shahaba Division of Water Resources and Arid Land Department of HydrogeochemistryDesert Research CenterCairoEgypt Egypt Desalination Research Center of Excellence Desert Research CenterCairoEgypt Center for Water Supply Studies S&E-Physical&Environmental SciencesTexas A&M University Corpus ChristiCorpus ChristiUSA Department of Chemistry Faculty of Science(Girls)Al-Azhar UniversityYousef Abbas StrNasr CityP.O.Box:11754CairoEgypt

The wadi dahab delta is in a dry, arid coastal zone within Egypt’s south Sinai Peninsula’s eastern portion. The primary water source is the Quaternary coastal alluvial aquifer. The groundwater salinity varies from 890to 8213 mg/L, with a mean value of 3417 mg/L. The dissolved major ions have been used to calculate the seawater mixing index(SWMI) using a linear equation that discriminates the groundwater mostly affected by water–rock interaction(SWMI 1>) and other samples mixed with Seawater(SWMI < 1). The isotopic composition of groundwater for specifically chosen groundwater samples ranges from-0.645‰ to +5.212‰ for δ^(18)O and from-9.582‰ to + 22.778‰ for δ^(2)H, where the seawater represented by a Red Sea water sample(δ^(18)O + 1.64‰-δ^(2)H + 9.80‰) and reject brine water are considerably enriched the isotopic groundwater values. The geochemical NETPATH model constrained by the dissolved significant ions, isotopes, and the rock aquifer forming minerals as phases indicate the mixing percent with the seawater ranges from 9% to 97% of seawater from 91% to 3% of original recharge water. According to the SEAWAT 3-D flow models, seawater has penetrated the Northeastern Dahab delta aquifer, with the intrusion zone extending1500 m inland. The salt dissolution, upwelling of saline water, recharge from the upstream mountain block, and seawater encroachment are the primary aspects contributing to the deterioration of groundwater quality. These findings may have significance for effective groundwater withdrawal management in arid locations worldwide with similar hydrogeological systems.

关键词： Groundwater geochemistry Seawater intrusion solute transport SEAWAT

A NEW NUMERICAL METHOD FOR GROUNDWATER FIOW AND solute transport USING VELOCITY FIELD

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Journal of Hydrodynamics 2008年第3期20卷 356-364页

作者： ZHANG Qian-fei LAN Shou-qi WANG Yan-ming XU Yong-fu School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China Shanghai Municipal Engineering Design Institute Shanghai 200092 China Department of Geotechnical Engineering Tongji University Shanghai 200092 China

A new numerical method for groundwater flow analysis was introduced to estimate simultaneously velocity vectors and water pressure head. The method could be employed to handle the vertical flow under variably saturated conditions and for horizontal flow as well. The method allows for better estimation of velocities at the element nodes which can be used as direct input to transport models. The advection-dispersion process was treated by the Eulerian-Lagrangian approach with particle tracking technique using the velocities at FEM nodes. The method was verified with the classical one dimensional model and applied to simulate contaminant transport process through a slurry wall as a barrier to prevent leachate pollution from a sanitary landfill.

关键词： groundwater flow solute transport velocity vectors finite element method Eulerian-Lagrangian approach particletracking technique

Unsaturated flow and solute transport in a porous column using spherical ore particles

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 113-121页

作者： Xiu-xiu Miao Ai-xiang Wu Bao-hua Yang Jin-zhi Liu Sheng-hua Yin Hong-jiang Wang Key Laboratory of High-Efficient Mining and Safety of Metal Mines (Ministry of Education) University of Science and Technology Beijing School of Information Science and Engineering Hunan International Economics University College of Information Technology Shanghai Ocean University

This paper dealt with the development of a two-dimensional （2D） mathematical model for column leaching and confirmed the important simulation parameters through experiment. The unsaturated state of the variably saturated flow column and the solute transport of copper ions were studied during leaching. The fluid flow problem was handled using the Richards equation on the premise of an ambient pressure column air, where the van Genuchten formulas were applied to define the nonlinear relationships of pressure head with the retention and permeability properties. The ore column permeability test gave a varied hydraulic conductivity, which was analyzed in the model. In the solute transport problem, the copper ion concentration was solved using the advection-diffusion-reaction equation whose reaction term was determined by the joint analysis of experimental copper leaching rate and the shrinking core model. Particle-and column-scale leaching tests were carried out to illustrate the difference and connection of copper extraction in both processes. This fluid flow and solute transport cou-pled model was determined through the finite element method using the numerical simulation software, COMSOL Multiphysics.

关键词： mathematical models leaching unsaturated flow solute transport

A SIMPLIFIED NUMERICAL MODEL OF 3-D GROUNDWATER AND solute transport AT LARGE SCALE AREA

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Journal of Hydrodynamics 2010年第3期22卷 319-328页

作者： LIN Lin YANG Jin-Zhong ZHANG Bin ZHU Yan State Key Laboratory of Water Resources and Hydropower Engineering Wuhan University Wuhan 430072China Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China

A simplified numerical model of groundwater and solute transport is developed. At large scale area there exists a big spatial scale difference between horizontal and vertical length scales. In the resultant model, the seepage region is particularly divided into several virtual layers along the z direction and vertical 1-D columns covering x-y 2-D area according to stratum properties. The numerical algorithm is replacing the full 3-D water and mass balance analysis as the 2-D Galerkin finite element method in x- and y-directions and 1-D finite differential approach in the z direction. The reasonable method of giving minimum thickness is successfully used to handle transient change of water table, drying cells and problem of rewetting. The solution of the simplified model is preconditioned conjugate gradient and ORTHOMIN method. The validity of the developed 3-D groundwater model is tested with the typical pumping and backwater scenarios. Results of water balance of the computed example reveal the model computation reliability. Based on a representative 3-D pollution case, the solute transport module is tested against computing results using the MT3DMS. The capability and high efficiency to predict non-stationary situations of free groundwater surface and solute plume in regional scale problem is quantitatively investigated. It is shown that the proposed model is computationally effective.

关键词： groundwater movement solute transport simplified model 3-D mass balance numerical simulation

LABORATORY EXPERIMENTS ON solute transport IN A PARTIAL TRANSFIXION SINGLE FRACTURE

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Journal of Hydrodynamics 2011年第5期23卷 570-579页

作者： CAI Jin-long ZHOU Zhi-fang HUANG Yong School of Earth Science and Engineering Hohai University Nanjing 210098 China

In the study of solute transport in rough single fracture, the contact area is an important factor. The single fracture is defined as two categories in this article： the full transfixion single fracture and the partial transfixion single fracture. The purpose of this article is to research how the contact area affects the solute transport in partial transfixion single fracture. The contact area is generalized as square blocks with three sizes, and contact rate is variable, a series of experiments for solute transport were conducted in a simulation model which can simulate the two types of fractures in the laboratory. Based on the analysis of the breakthrough curves and the experiment phenomena, it is concluded that the difference of breakthrough curves of various contact rates is evident and increases with the increase of contact rate, the relative error curves reflect the difference of block sizes, and the maximum errors increase from smaller than 0.2 to about 0.8 with the increase of contact rate. These phenomena are also explained qualitatively in this article. It is concluded that the contact area strongly affects solute transport, and the research of channels formed by contact area is useful to further understand the rule of solute transport in partial transfixion single fracture.

关键词： contact rate channels partial transfixion single fracture solute transport

Modelling of solute transport in a filled fracture: Effects of heterogeneity of filled medium

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Journal of Hydrodynamics 2015年第1期27卷 85-92页

作者：窦智周志芳 School of Earth Sciences and Engineering Hohai University

In this paper, the developed lattice Boltzmalm method （LBM） is used to model the solute transport in a filled fracture under a heterogeneous advective velocity field. The results of the developed LBM in modelling the solute transport are compared with the published experimental data. The numerically derived BTCs indicate that the distribution of the filled medium in the fracture has a significant effect on the characteristics of the BTCs, even with the same porosity. The heterogeneity of the filled medium is responsible not only for the heterogeneous advective velocity field but also for the early arrival and long tails of the BTCs. The long tailings of the BTCs increase their length with the increase of the duration of the input pulse. Furthermore, the BTCs obtained from the LBM simulations are well consistent with the two-region model （TRM）. The fitting results show that the fractional mobile region varies with the distribution of the filled medium. The long tailings of the BTCs increase their length with the increase of the immobile region while the concentration peak value increases with the increase of the mobile region.

关键词： solute transport heterogeneity lattice Boltzmann method two-region model fracture

Effect of nozzle type on fluid flow, solidification, and solute transport in mold with mold electromagnetic stirring

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Journal of Iron and Steel Research International 2022年第2期29卷 237-246页

作者： Ya-dong Wang Li-feng Zhang Wen Yang Ying Ren School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing100083China State Key Lab of Metastable Materials Science and Technology School of Mechanical EngineeringYanshan UniversityQinhuangdao066004HebeiChina

The mathematical model of coupling fluid flow,heat transfer,solidification,solute transport,and the electromagnetic field of the bloom in the upper part of the strand was established with three nozzle ***,the flow field,distribution of the temperature,solidification,and macrosegregation of carbon were investigated and compared by numerical *** the case of the straight submerged entry nozzle(SEN),the molten steel flows down deep into the liquid pool,and the depth of the jet flow reaches about 1.0 m beneath the *** jetting zone is the high-temperature *** the case of two-port SEN and four-port SEN,the flow patterns and distribution of temperature in the central longitudinal section are *** jet flow impinges directly on the initially solidified shell and then it is divided into two longitudinal *** heat of molten steel is dissipated along with the longitudinal *** negative segregation band was generated near the bloom surface due to the washing effect by the rotating flow at the solidification front with three nozzle *** negative segregation deteriorates gradually with the number of ports decreasing.

关键词： Submerged entry nozzle Fluid flow Solidification solute transport Mold electromagnetic stirring

SIMULATION OF solute transport IN A PARALLEL SINGLE FRACTURE WITH LBM/MMP MIXED METHOD

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Journal of Hydrodynamics 2008年第3期20卷 365-372页

作者： TAN Ye-fei ZHOU Zhi-fang College of Civil Engineering Hohai University NanJing 210098 China

This article deals with the solute transport in a single fracture with the combination of the Lattice Boltzmann Method （LBM） and Modified Moment Propagation （MMP） method, and this mixed method is proved to have several advantages over the LBM and Moment Propagation （MP） mixed method which leads to negative concentrations under some conditions in computation. The disadvantage of LBM/MP has been overcome to a certain extent. Also, this work presents an LBM solution of modeling single fractures with uniformly or randomly distributed grains, which can provide a new path of applying the LBM in solute transport simulation in fractures.

关键词： Lattice Boltzmann Method (LBM) Modified Moment Propagation (MMP) method LBM/MMP mixed method single fracture solute transport rough fracture