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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

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

FORMULAE FOR AVERAGE VELOCITY OF GROUNDWATER FLOW AND EXPERIMENTAL EVIDENCE OF NON-DARCY' S FLOW THROUGH A single fracture

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Journal of Hydrodynamics 2003年第6期15卷 56-62页

作者： QianJia-zhong WangJia-quan LiRu-zhong LiuYong SchoolofResourcesandEnvironmentEngineering HefeiUniversityofTechnologyHefei230009China SchoolofBiologyandFoodEngineering HefeiUniversityofTechnologyHefei230009China

The formulae for average velocity of groundw-ater flow in a single fracturewere derived based on the characteristics of fracture properties and hydraulic methods. The resultsshow that the average velocity is proportional to the square root of the hydraulic gradient. Inorder to verify the results, a laboratory model was established, and the experimental data wereanalyzed. Experimental results indicate that the relation between the average velocity and hydraulicgradient is nonlinear, and can he filled with power functions. And for both the unconfined andconfined flows, the value of the exponent of power functions are close to 0. 5. Thus the experimental results agree well with those from the theoretical analysis. By comparing the calculated andmeasured values of the average velocity under the same conditions, the formulae presented herein aremore effective than the traditional formula based on Darcy' s Law. These results provide theevidences of non-Dar-cy's flow in single fracture.

关键词： single fracture formulae for average velocity non-darcy's flow experimental verification

Revisit of advection-dispersion equation model with velocity-dependent dispersion in capturing tracer dynamics in single empty fractures

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Journal of Hydrodynamics 2018年第6期30卷 1055-1063页

作者：王沐赵卫东 Rhiannon Garrard Yong Zhang 刘咏钱家忠 School of Resources and Environmental Engineering Hefei University of Technology Department of Geological Sciences University of Alabama College of Mechanics and Materials Hohai University School of Food and Biotechnology Engineering Hefei University of Technology

An accurate quantification of the contaminant transport through fractured media is critical for dealing with water-quality related scientific and engineering issues, where the dispersion coefficient is an important and elusive parameter for the solute transport modeling. Many previous studies show that the dispersion coefficient(D) in the standard advection-dispersion equation(ADE) model can be approximated by D=avλ(where a is the dispersivity), a formula to be revisited systematically in this study by laboratory experiments and model analysis. First, a series of tracer transport experiments in single empty fractures are conducted in cases of different hydraulic gradients. Second, the tracer breakthrough curves are determined by simulations based on the ADE model, to obtain the dispersion coefficients corresponding to various fracture roughnesses and flow velocities. A varying trend of λ is analyzed under different flow conditions. Results show that although the standard ADE model cannot be used to characterize the late-time tailing of the tracer BTCs, likely due to the solute retention, this simple model can simulate most of the solute mass dynamics moving through fractures and may therefore provide information for estimating the dispersion in parsimonious models appropriate for the non-Fickian transport. The following three conclusions are drawn:(1) the peak of the breakthrough curves comes earlier with increasing the roughness, according to the ADE simulation,(2) the value of λ generally decreases as the relative roughness of the fracture increases,(3) the value of λ is approximately equal to 2.0 when the dispersion is dominated by the molecular diffusion in the smooth fracture.

关键词： Dispersion coefficient molecular diffusion roughness variation trend single fracture

Numerical simulations of seepage flow in rough single rock fractures

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Petroleum 2015年第3期1卷 200-205页

作者： Qingang Zhang Yang Ju Wenbo Gong Liang Zhang Huafei Sun School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing 10083China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyBeijing 100083China

To investigate the relationship between the structural characteristics and seepage flow behavior of rough single rock fractures,a set of single fracture physical models were produced using the WeierstrasseMandelbrot functions to test the seepage flow performance.Six single fractures,with various surface roughnesses characterized by fractal dimensions,were built using COMSOL multiphysics software.The fluid flow behavior through the rough fractures and the influences of the rough surfaces on the fluid flow behavior was then monitored.The numerical simulation indicates that there is a linear relationship between the average flow velocity over the entire flow path and the fractal dimension of the rough surface.It is shown that there is good agreement between the numerical results and the experimental data in terms of the properties a of the fluid flowing through the rough single rock fractures.

关键词： Seepage flow single fracture Rough surface Fractal dimension fractured rock