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Chen-wuing Liu - One of the best experts on this subject based on the ideXlab platform.

  • Generalized analytical solutions to sequentially coupled multi-species advective-Dispersive Transport equations in a finite domain subject to an arbitrary time-dependent source boundary condition
    Journal of Hydrology, 2012
    Co-Authors: Jui-sheng Chen, Chen-wuing Liu, Ching-ping Liang, Keng-hsin Lai
    Abstract:

    Summary Multi-species advective–Dispersive Transport equations sequentially coupled with first-order decay reactions are widely used to describe the Transport and fate of the decay chain contaminants such as radionuclide, chlorinated solvents, and nitrogen. Although researchers attempted to present various types of methods for analytically solving this Transport equation system, the currently available solutions are mostly limited to an infinite or a semi-infinite domain. A generalized analytical solution for the coupled multi-species Transport problem in a finite domain associated with an arbitrary time-dependent source boundary is not available in the published literature. In this study, we first derive generalized analytical solutions for this Transport problem in a finite domain involving arbitrary number of species subject to an arbitrary time-dependent source boundary. Subsequently, we adopt these derived generalized analytical solutions to obtain explicit analytical solutions for a special-case Transport scenario involving an exponentially decaying Bateman type time-dependent source boundary. We test the derived special-case solutions against the previously published coupled 4-species Transport solution and the corresponding numerical solution with coupled 10-species Transport to conduct the solution verification. Finally, we compare the new analytical solutions derived for a finite domain against the published analytical solutions derived for a semi-infinite domain to illustrate the effect of the exit boundary condition on coupled multi-species Transport with an exponential decaying source boundary. The results show noticeable discrepancies between the breakthrough curves of all the species in the immediate vicinity of the exit boundary obtained from the analytical solutions for a finite domain and a semi-infinite domain for the dispersion-dominated condition.

  • a novel method for analytically solving multi species advective Dispersive Transport equations sequentially coupled with first order decay reactions
    Journal of Hydrology, 2012
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Chen-wuing Liu
    Abstract:

    Summary Analytical solutions for coupled multi-species solute Transport problems are difficult to derive and relatively few in subsurface hydrology. Decomposition strategy such as linear transform format or matrix diagonalization method which decomposes the set of coupled advective–Dispersive Transport equations into a system of independent differential equations have been widely used to derive the analytical solution for coupled multi-species solute Transport problem. These decomposition techniques are generally limited to derive the analytical solution for an infinite or a semi-infinite domain. In this study, we present a novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled by first-order decay reactions. The method first performs Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate to convert the set of partial differential equations into a system of algebraic equations. Subsequently, the system of algebraic equations is solved using simple algebraic manipulation, thus the concentrations in the transformed domain for each species can be independently obtained. Ultimately, the concentrations in the original domain for all species are obtained by successive application of Laplace and the corresponding generalized integral transform inversions. A coupled four-species Transport problem in a finite domain is used to demonstrate the robustness of the proposed method for deriving the analytical solutions associated with sequentially coupled multi-species solute Transport problem. The developed analytical solution is tested by comparing their results against those generated with the corresponding numerical solutions. Results show perfect agreements between the analytical and numerical solutions. Moreover, the developed analytical solution is compared with the analytical solutions for a semi-infinite domain available in literature to illustrate the impacts of the exit boundary conditions on coupled multi-species Transport. It is observed that significant discrepancies exist between two solutions for small Peclet numbers, whereas two solutions deviate negligibly each other for medium Peclet numbers.

  • A novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled with first-order decay reactions
    Journal of Hydrology, 2011
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Chen-wuing Liu
    Abstract:

    Summary Analytical solutions for coupled multi-species solute Transport problems are difficult to derive and relatively few in subsurface hydrology. Decomposition strategy such as linear transform format or matrix diagonalization method which decomposes the set of coupled advective–Dispersive Transport equations into a system of independent differential equations have been widely used to derive the analytical solution for coupled multi-species solute Transport problem. These decomposition techniques are generally limited to derive the analytical solution for an infinite or a semi-infinite domain. In this study, we present a novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled by first-order decay reactions. The method first performs Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate to convert the set of partial differential equations into a system of algebraic equations. Subsequently, the system of algebraic equations is solved using simple algebraic manipulation, thus the concentrations in the transformed domain for each species can be independently obtained. Ultimately, the concentrations in the original domain for all species are obtained by successive application of Laplace and the corresponding generalized integral transform inversions. A coupled four-species Transport problem in a finite domain is used to demonstrate the robustness of the proposed method for deriving the analytical solutions associated with sequentially coupled multi-species solute Transport problem. The developed analytical solution is tested by comparing their results against those generated with the corresponding numerical solutions. Results show perfect agreements between the analytical and numerical solutions. Moreover, the developed analytical solution is compared with the analytical solutions for a semi-infinite domain available in literature to illustrate the impacts of the exit boundary conditions on coupled multi-species Transport. It is observed that significant discrepancies exist between two solutions for small Peclet numbers, whereas two solutions deviate negligibly each other for medium Peclet numbers.

Jui-sheng Chen - One of the best experts on this subject based on the ideXlab platform.

  • Exact analytical solutions for three-dimensional multispecies advective-Dispersive Transport equations sequentially coupled with first-order decay reactions in a semi-infinite domain
    2020
    Co-Authors: Zhong-yi Liao, Jui-sheng Chen
    Abstract:

    <p>Analytical solutions to a set of simultaneous multispecies advective-Dispersive Transport equations sequentially coupled with first-order decay reactions have been widely used to describe the movements of decaying or degradable contaminants such as chlorinated solvents, nitrogens and pesticides in the subsurface. This study presents an exact analytical solutions for three-dimensional coupled multispecies Transport in a semi-finite domain. The analytical model are derived for both the first-type and third-type inlet boundary conditions. A method of consecutive applications of three integral transformation techniques in combination with sequential substitutions is adopted to derive the analytical solutions to the governing equation system. The developed analytical model is robustly verified with a chlorinated solvent Transport problem. It is applied to investigate the effect of inlet-boundary conditions on the multispecies plume migration and the model could be a very efficient tool that can be used to simulate the degradable contaminant sites.</p><p>請在此處插入您的抽象HTML。</p>

  • Analytical model for advective-Dispersive Transport involving flexible boundary inputs, initial distributions and zero-order productions
    Journal of Hydrology, 2017
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Ching-ping Liang
    Abstract:

    Abstract A novel solution method is presented which leads to an analytical model for the advective-Dispersive Transport in a semi-infinite domain involving a wide spectrum of boundary inputs, initial distributions, and zero-order productions. The novel solution method applies the Laplace transform in combination with the generalized integral transform technique (GITT) to obtain the generalized analytical solution. Based on this generalized analytical expression, we derive a comprehensive set of special-case solutions for some time-dependent boundary distributions and zero-order productions, described by the Dirac delta, constant, Heaviside, exponentially-decaying, or periodically sinusoidal functions as well as some position-dependent initial conditions and zero-order productions specified by the Dirac delta, constant, Heaviside, or exponentially-decaying functions. The developed solutions are tested against an analytical solution from the literature. The excellent agreement between the analytical solutions confirms that the new model can serve as an effective tool for investigating Transport behaviors under different scenarios. Several examples of applications, are given to explore Transport behaviors which are rarely noted in the literature. The results show that the concentration waves resulting from the periodically sinusoidal input are sensitive to dispersion coefficient. The implication of this new finding is that a tracer test with a periodic input may provide additional information when for identifying the dispersion coefficients. Moreover, the solution strategy presented in this study can be extended to derive analytical models for handling more complicated problems of solute Transport in multi-dimensional media subjected to sequential decay chain reactions, for which analytical solutions are not currently available.

  • Generalized analytical solutions to sequentially coupled multi-species advective-Dispersive Transport equations in a finite domain subject to an arbitrary time-dependent source boundary condition
    Journal of Hydrology, 2012
    Co-Authors: Jui-sheng Chen, Chen-wuing Liu, Ching-ping Liang, Keng-hsin Lai
    Abstract:

    Summary Multi-species advective–Dispersive Transport equations sequentially coupled with first-order decay reactions are widely used to describe the Transport and fate of the decay chain contaminants such as radionuclide, chlorinated solvents, and nitrogen. Although researchers attempted to present various types of methods for analytically solving this Transport equation system, the currently available solutions are mostly limited to an infinite or a semi-infinite domain. A generalized analytical solution for the coupled multi-species Transport problem in a finite domain associated with an arbitrary time-dependent source boundary is not available in the published literature. In this study, we first derive generalized analytical solutions for this Transport problem in a finite domain involving arbitrary number of species subject to an arbitrary time-dependent source boundary. Subsequently, we adopt these derived generalized analytical solutions to obtain explicit analytical solutions for a special-case Transport scenario involving an exponentially decaying Bateman type time-dependent source boundary. We test the derived special-case solutions against the previously published coupled 4-species Transport solution and the corresponding numerical solution with coupled 10-species Transport to conduct the solution verification. Finally, we compare the new analytical solutions derived for a finite domain against the published analytical solutions derived for a semi-infinite domain to illustrate the effect of the exit boundary condition on coupled multi-species Transport with an exponential decaying source boundary. The results show noticeable discrepancies between the breakthrough curves of all the species in the immediate vicinity of the exit boundary obtained from the analytical solutions for a finite domain and a semi-infinite domain for the dispersion-dominated condition.

  • a novel method for analytically solving multi species advective Dispersive Transport equations sequentially coupled with first order decay reactions
    Journal of Hydrology, 2012
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Chen-wuing Liu
    Abstract:

    Summary Analytical solutions for coupled multi-species solute Transport problems are difficult to derive and relatively few in subsurface hydrology. Decomposition strategy such as linear transform format or matrix diagonalization method which decomposes the set of coupled advective–Dispersive Transport equations into a system of independent differential equations have been widely used to derive the analytical solution for coupled multi-species solute Transport problem. These decomposition techniques are generally limited to derive the analytical solution for an infinite or a semi-infinite domain. In this study, we present a novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled by first-order decay reactions. The method first performs Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate to convert the set of partial differential equations into a system of algebraic equations. Subsequently, the system of algebraic equations is solved using simple algebraic manipulation, thus the concentrations in the transformed domain for each species can be independently obtained. Ultimately, the concentrations in the original domain for all species are obtained by successive application of Laplace and the corresponding generalized integral transform inversions. A coupled four-species Transport problem in a finite domain is used to demonstrate the robustness of the proposed method for deriving the analytical solutions associated with sequentially coupled multi-species solute Transport problem. The developed analytical solution is tested by comparing their results against those generated with the corresponding numerical solutions. Results show perfect agreements between the analytical and numerical solutions. Moreover, the developed analytical solution is compared with the analytical solutions for a semi-infinite domain available in literature to illustrate the impacts of the exit boundary conditions on coupled multi-species Transport. It is observed that significant discrepancies exist between two solutions for small Peclet numbers, whereas two solutions deviate negligibly each other for medium Peclet numbers.

  • A novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled with first-order decay reactions
    Journal of Hydrology, 2011
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Chen-wuing Liu
    Abstract:

    Summary Analytical solutions for coupled multi-species solute Transport problems are difficult to derive and relatively few in subsurface hydrology. Decomposition strategy such as linear transform format or matrix diagonalization method which decomposes the set of coupled advective–Dispersive Transport equations into a system of independent differential equations have been widely used to derive the analytical solution for coupled multi-species solute Transport problem. These decomposition techniques are generally limited to derive the analytical solution for an infinite or a semi-infinite domain. In this study, we present a novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled by first-order decay reactions. The method first performs Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate to convert the set of partial differential equations into a system of algebraic equations. Subsequently, the system of algebraic equations is solved using simple algebraic manipulation, thus the concentrations in the transformed domain for each species can be independently obtained. Ultimately, the concentrations in the original domain for all species are obtained by successive application of Laplace and the corresponding generalized integral transform inversions. A coupled four-species Transport problem in a finite domain is used to demonstrate the robustness of the proposed method for deriving the analytical solutions associated with sequentially coupled multi-species solute Transport problem. The developed analytical solution is tested by comparing their results against those generated with the corresponding numerical solutions. Results show perfect agreements between the analytical and numerical solutions. Moreover, the developed analytical solution is compared with the analytical solutions for a semi-infinite domain available in literature to illustrate the impacts of the exit boundary conditions on coupled multi-species Transport. It is observed that significant discrepancies exist between two solutions for small Peclet numbers, whereas two solutions deviate negligibly each other for medium Peclet numbers.

Keng-hsin Lai - One of the best experts on this subject based on the ideXlab platform.

  • Analytical model for advective-Dispersive Transport involving flexible boundary inputs, initial distributions and zero-order productions
    Journal of Hydrology, 2017
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Ching-ping Liang
    Abstract:

    Abstract A novel solution method is presented which leads to an analytical model for the advective-Dispersive Transport in a semi-infinite domain involving a wide spectrum of boundary inputs, initial distributions, and zero-order productions. The novel solution method applies the Laplace transform in combination with the generalized integral transform technique (GITT) to obtain the generalized analytical solution. Based on this generalized analytical expression, we derive a comprehensive set of special-case solutions for some time-dependent boundary distributions and zero-order productions, described by the Dirac delta, constant, Heaviside, exponentially-decaying, or periodically sinusoidal functions as well as some position-dependent initial conditions and zero-order productions specified by the Dirac delta, constant, Heaviside, or exponentially-decaying functions. The developed solutions are tested against an analytical solution from the literature. The excellent agreement between the analytical solutions confirms that the new model can serve as an effective tool for investigating Transport behaviors under different scenarios. Several examples of applications, are given to explore Transport behaviors which are rarely noted in the literature. The results show that the concentration waves resulting from the periodically sinusoidal input are sensitive to dispersion coefficient. The implication of this new finding is that a tracer test with a periodic input may provide additional information when for identifying the dispersion coefficients. Moreover, the solution strategy presented in this study can be extended to derive analytical models for handling more complicated problems of solute Transport in multi-dimensional media subjected to sequential decay chain reactions, for which analytical solutions are not currently available.

  • Generalized analytical solutions to sequentially coupled multi-species advective-Dispersive Transport equations in a finite domain subject to an arbitrary time-dependent source boundary condition
    Journal of Hydrology, 2012
    Co-Authors: Jui-sheng Chen, Chen-wuing Liu, Ching-ping Liang, Keng-hsin Lai
    Abstract:

    Summary Multi-species advective–Dispersive Transport equations sequentially coupled with first-order decay reactions are widely used to describe the Transport and fate of the decay chain contaminants such as radionuclide, chlorinated solvents, and nitrogen. Although researchers attempted to present various types of methods for analytically solving this Transport equation system, the currently available solutions are mostly limited to an infinite or a semi-infinite domain. A generalized analytical solution for the coupled multi-species Transport problem in a finite domain associated with an arbitrary time-dependent source boundary is not available in the published literature. In this study, we first derive generalized analytical solutions for this Transport problem in a finite domain involving arbitrary number of species subject to an arbitrary time-dependent source boundary. Subsequently, we adopt these derived generalized analytical solutions to obtain explicit analytical solutions for a special-case Transport scenario involving an exponentially decaying Bateman type time-dependent source boundary. We test the derived special-case solutions against the previously published coupled 4-species Transport solution and the corresponding numerical solution with coupled 10-species Transport to conduct the solution verification. Finally, we compare the new analytical solutions derived for a finite domain against the published analytical solutions derived for a semi-infinite domain to illustrate the effect of the exit boundary condition on coupled multi-species Transport with an exponential decaying source boundary. The results show noticeable discrepancies between the breakthrough curves of all the species in the immediate vicinity of the exit boundary obtained from the analytical solutions for a finite domain and a semi-infinite domain for the dispersion-dominated condition.

  • a novel method for analytically solving multi species advective Dispersive Transport equations sequentially coupled with first order decay reactions
    Journal of Hydrology, 2012
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Chen-wuing Liu
    Abstract:

    Summary Analytical solutions for coupled multi-species solute Transport problems are difficult to derive and relatively few in subsurface hydrology. Decomposition strategy such as linear transform format or matrix diagonalization method which decomposes the set of coupled advective–Dispersive Transport equations into a system of independent differential equations have been widely used to derive the analytical solution for coupled multi-species solute Transport problem. These decomposition techniques are generally limited to derive the analytical solution for an infinite or a semi-infinite domain. In this study, we present a novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled by first-order decay reactions. The method first performs Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate to convert the set of partial differential equations into a system of algebraic equations. Subsequently, the system of algebraic equations is solved using simple algebraic manipulation, thus the concentrations in the transformed domain for each species can be independently obtained. Ultimately, the concentrations in the original domain for all species are obtained by successive application of Laplace and the corresponding generalized integral transform inversions. A coupled four-species Transport problem in a finite domain is used to demonstrate the robustness of the proposed method for deriving the analytical solutions associated with sequentially coupled multi-species solute Transport problem. The developed analytical solution is tested by comparing their results against those generated with the corresponding numerical solutions. Results show perfect agreements between the analytical and numerical solutions. Moreover, the developed analytical solution is compared with the analytical solutions for a semi-infinite domain available in literature to illustrate the impacts of the exit boundary conditions on coupled multi-species Transport. It is observed that significant discrepancies exist between two solutions for small Peclet numbers, whereas two solutions deviate negligibly each other for medium Peclet numbers.

  • A novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled with first-order decay reactions
    Journal of Hydrology, 2011
    Co-Authors: Jui-sheng Chen, Keng-hsin Lai, Chen-wuing Liu
    Abstract:

    Summary Analytical solutions for coupled multi-species solute Transport problems are difficult to derive and relatively few in subsurface hydrology. Decomposition strategy such as linear transform format or matrix diagonalization method which decomposes the set of coupled advective–Dispersive Transport equations into a system of independent differential equations have been widely used to derive the analytical solution for coupled multi-species solute Transport problem. These decomposition techniques are generally limited to derive the analytical solution for an infinite or a semi-infinite domain. In this study, we present a novel method for analytically solving multi-species advective–Dispersive Transport equations sequentially coupled by first-order decay reactions. The method first performs Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate to convert the set of partial differential equations into a system of algebraic equations. Subsequently, the system of algebraic equations is solved using simple algebraic manipulation, thus the concentrations in the transformed domain for each species can be independently obtained. Ultimately, the concentrations in the original domain for all species are obtained by successive application of Laplace and the corresponding generalized integral transform inversions. A coupled four-species Transport problem in a finite domain is used to demonstrate the robustness of the proposed method for deriving the analytical solutions associated with sequentially coupled multi-species solute Transport problem. The developed analytical solution is tested by comparing their results against those generated with the corresponding numerical solutions. Results show perfect agreements between the analytical and numerical solutions. Moreover, the developed analytical solution is compared with the analytical solutions for a semi-infinite domain available in literature to illustrate the impacts of the exit boundary conditions on coupled multi-species Transport. It is observed that significant discrepancies exist between two solutions for small Peclet numbers, whereas two solutions deviate negligibly each other for medium Peclet numbers.

V. I. Arkhipov - One of the best experts on this subject based on the ideXlab platform.

  • Trap-controlled Dispersive Transport in systems of randomly fluctuating localized states
    Philosophical Magazine B, 1997
    Co-Authors: V. I. Arkhipov, G.j. Adriaenssens
    Abstract:

    Abstract Trap-controlled Dispersive carrier Transport and recombination are considered in materials with fluctuating localized states. Under these conditions the distribution of effective activation energies (DEAE) can be different from the momentary energy distribution of localized states. The former rather than the latter governs kinetics of all processes which are controlled by trapping and release of charge carriers. It is shown that Deae and the momentary distribution are rather similar for shallow states and can be very different for sufficiently deep traps. As a result, the fluctuations do not affect Dispersive Transport characteristics at short times but either terminate the Dispersive Transport or make its characterisrics temperature independent at longer times.

  • An adiabatic model of trap-controlled Dispersive Transport and recombination
    Journal of Non-Crystalline Solids, 1993
    Co-Authors: V. I. Arkhipov
    Abstract:

    Abstract A model of trap-controlled Dispersive Transport and recombination is presented. Carrier Transport and recombination under non-equilibrium conditions are shown to have features characteristic of an adiabatic process with the time-dependent density of ‘deep’ localized states being a rate-limiting function. Hence the latter function governs time dependencies of Dispersive Transport and recombination. An adiabatic equation of trap-controlled Dispersive Transport and recombination is derived. The general results are applied to particular models of energetic distribution of localized states.

  • Space-charge Dispersive Transport in corona-charged dielectrics
    Journal of Electrostatics, 1993
    Co-Authors: V. I. Arkhipov, A. I. Rudenko, D.v. Khramchenkov, Gerhard M. Sessler
    Abstract:

    Abstract A model of radiation-induced space-charge kinetics in non-crystalline dielectrics during continuous irradiation with charged particles of range much smaller than the thickness of the sample is developed. The Dispersive Transport of space charge is considered using the multiple-trapping model with exponential energy spectrum of localized states. Open-circuit conditions are analyzed with rear electrode grounded. Analytical solutions for time-dependent spatial distributions of space-charge density and electric field strength are obtained. It is shown that the voltage across the sample increases as a sublinear function of irradiation time.

  • Transient current measurements in double-layer structures as a method of investigating Dispersive Transport
    Philosophical Magazine B, 1992
    Co-Authors: V. I. Arkhipov, L. P. Kazakova, E. A. Lebedev, A. I. Rudenko
    Abstract:

    Abstract Experimental studies of the drifting hole packet shape in vitreous As2Se3,have been made using double-layer structures. It is found that the time t mcorresponding to a maximum of the delocalized carrier density at the collection electrode, is approximately the same as the transit time,t T, of the drifting carrier packet in the sample. It has been theoretically established that, in case of Dispersive Transport, the ratio (t m,/t T) is always less than unity. A comparison of theoretical and experimental results suggests that the hole drift in As2,Se3, at room temperature displays many features of normal Gaussian Transport.

  • Space-charge Dispersive Transport in corona-charged dielectrics
    [1992] Proceedings of the 4th International Conference on Conduction and Breakdown in Solid Dielectrics, 1
    Co-Authors: V. I. Arkhipov, A. I. Rudenko, D.v. Kramchenkov, Gerhard M. Sessler
    Abstract:

    Summary form only given. The authors suggest a model of space-charge Dispersive Transport in noncrystalline dielectrics under the condition of continuous surface carrier injection (corona charging). They consider a sample under open-circuit conditions with rear electrode grounded. Dispersive Transport of injected space charge is described within the framework of the carrier multiple-trapping model with the Poisson equation being taken into consideration. Approximate analytical and numerical solutions of the equation for the dimensionless electric field have been obtained. Using these solutions one may calculate time-dependent spatial distributions of the field and space-charge density, and time dependences of voltage and carrier packet mean position. >

Emil O. Frind - One of the best experts on this subject based on the ideXlab platform.

  • advective Dispersive Transport of dense organic vapors in the unsaturated zone 2 sensitivity analysis
    Water Resources Research, 1990
    Co-Authors: Carl A. Mendoza, Emil O. Frind
    Abstract:

    In the migration of dense organic vapors in the unsaturated zone, advection due to density gradients can play an important or even dominant role under certain conditions. Advective Transport can distribute contaminants over a wide area within the unsaturated zone, thus increasing the potential for groundwater contamination. The controls on gas phase advective-Dispersive Transport from a residual source of a generic organic compound are investigated using a numerical model. A sensitivity analysis reveals that, for compounds with high vapor pressures and molecular weights, in high permeability environments (coarse sands or gravels), the mass Transported by density-dependent advection may greatly exceed that Transported by diffusion alone. If density-dependent advection is the dominant Transport mechanism, the extent of the contaminated area is increased if the ground surface is open to the atmosphere, rather than covered. The opposite is true for a diffusion-controlled system. For either case an open ground surface contributes to a more rapid depletion of the residual liquid source. The advective mass flux caused by the release of vapor due to vaporization at the source is seen to be of minor importance.

  • Advective‐Dispersive Transport of dense organic vapors in the unsaturated zone: 2. Sensitivity analysis
    Water Resources Research, 1990
    Co-Authors: Carl A. Mendoza, Emil O. Frind
    Abstract:

    In the migration of dense organic vapors in the unsaturated zone, advection due to density gradients can play an important or even dominant role under certain conditions. Advective Transport can distribute contaminants over a wide area within the unsaturated zone, thus increasing the potential for groundwater contamination. The controls on gas phase advective-Dispersive Transport from a residual source of a generic organic compound are investigated using a numerical model. A sensitivity analysis reveals that, for compounds with high vapor pressures and molecular weights, in high permeability environments (coarse sands or gravels), the mass Transported by density-dependent advection may greatly exceed that Transported by diffusion alone. If density-dependent advection is the dominant Transport mechanism, the extent of the contaminated area is increased if the ground surface is open to the atmosphere, rather than covered. The opposite is true for a diffusion-controlled system. For either case an open ground surface contributes to a more rapid depletion of the residual liquid source. The advective mass flux caused by the release of vapor due to vaporization at the source is seen to be of minor importance.