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Porous media with linearly variable hydraulic properties
161A 923176 Second Las Cruces trench experiment: experimental results and two-dimemional flow predictions Hills, R G; Wierenga, P J; Hudson, D B; Kirkland, M R Water Resour Res V27, NIO, Oct 1991, P2707-2718
923180 Spatial and temporal moments of tracer concentration in disordered porous media
Field observations of water, tritium, and bromide movement during infiltration and redistribution at a heavily instrumented and well characterised site are described. Water and bromide moved fairly homogeneously during infiltration, with bromide ahead of tritium due to anion exclusion during redistribution. A two dimensional flow model gave predictions in qualitative agreement with measurements for 2 of the 3 water content measurement planes. Tracer transport was not as well predicted, with localised inhomogeneities and large downward motion of bromide with respect to tritium during redistribution not being reproduced.
Concentration distribution predictions are often required from irregularly sampled measurements. Geostatistical methods are well suited for such tasks. A method to derive the spatial and temporal moments of tracer concentration in a disordered geological medium is developed to allow interpolation and prediction of concentration, conditional to concentration measurements. It is based on a biparticle tracking scheme which yields the bivariate probability distribution function of particle displacements in terms of the input log conductivity random field and the prevailing flow conditions.
923177 Analytical solutions for solute transport in three-dimensional semi-infinite porous media Leij, F J; Skaggs, T H; van Genuchten, M T Water Resour Res V27, NIO, Oct 1991, P2719-2733 Analytical solutions are derived for the three dimensional advection-dispersion equation (ADE) during one dimensional flow in a 3D semi-infinite medium. The transport equation includes terms which account for linear equilibrium adsorption, zero-order production, and first-order decay. The ADE is solved subject to first type (concentration) and third type (flux) boundary conditions at the inlet location of the medium. Analytical solutions are derived using several integral transforms to reduce the partial differential equations to simplified algebraic expressions. Solutions are presented for 5 specific combinations of initial and boundary concentration profiles. 923178 Porous media with linearly variable hydraulic properties
Vogel, T; Cislerova, M; Hopmans, J W Water Resour Res V27, NIO, Oct 1991, P2735-2741 The functional similarity concept (Simmons et ai, 1979) is generalised and extended for the analysis of flow in a system of parallel, homogeneous, one-, two-, or three-dimensional soil profiles. The resulting invariance of Richard's equations for a set of soil profiles is valid for certain initial and boundary conditions only. Direct identification of scaling factors based on measured soil hydraulic properties or indirect identification based on measured dynamic characteristics of the soil water system are described. The concept may be used to classify soils according to the shape of their reference hydraulic properties or describe temporal or spatial variabilities of properties for use in numerical modelling. 923179 Empirical model of intrinsic permeability in reactive dayb e a r ~ snds gaffensperger, J P; Fen'ell, R E Water Resour Res V27, Nll, Nov 1991, 1'2835-2844 Permeability response of clay-containing sands to change in fluid composition has been examined. Tests used solutions of sodium and calcium chloride of different concentrations, plus freshwater flushing of salt-containing sediments and stepwise variation of fluid composition. Sediment specific surface areas and microstructures were studied. A nempirical model of permeability is developed including effects of porosity, mean pore size, and specific surface areas. Differences between measured permeabilities and Kozeny-Carruan predictions using the experimental data may be explained in terms of dead-end pores and large-channel flows.
Rubin, Y Water Resour Res V27, Nil, Nov 1991, P2845-2854
923181
Diffusion-controlled contaminant transport in landflD.elay liner systems Rowe, R K; Booker, J R Proc International Symposium on Computer and Pkydcul Modelling in Geoteclmicul Engineering, Bangkok, 3-6 December 1986 P509-520. Publ Rotterdam: ,4 A Balkema, 1989 This new technique, based on finite layer theory, is applicable to deposits which can be ideaiised as layers, and is not computationally intensive. Two dimensional analysis of a fully stratified deposit can be undertaken. An example investigates effect of physical and chemical parameters and advection velocity on escape of contaminant from a capped landfill. 923182
Effect of percolating structures on the petrophysieal properties of Berea sandstone Agrawal, D L; Cook, N G W; Myer, L R Rock Meclmules as a Multidisciplinary Scieace: Proc 32ad US Symposium, Nornum, 10-12 July 1991 P345-354. Publ Rotterdam: A A Baikema. 1991 The topography and heterogeneity of flow paths in Berea sandstone and Indiana limestone have been studied using Wood's metal porosimetry. Effects of path length and time on percolation were studied. Pore system differences for the two rock types were examined by SEM after the mineral grains had been etched away. The flow of fluid is strongly dependent on the length of the flow path from the free surface. As path length increases, the throats providing the interconnection between larger pores become smaller. The best connected pores become occupied, conductivity to future flow being reduced. 923183
Estimates of permeability and relative permeability m ~ l image analysis of cross sectinm Blair, S C; Berryman, J C Rock Meekames as a Multidiseip~mry ,~ieoce: Proc 32ml US Sympasi~n, Norton, 10-12 July 1991 P365-374. Publ Rotterdam: A A Balkema, 1991 Digitised images of rock cross sections, interpreted using statistical correlation functions, were used to provide information on total porosity and amount of pore space occupied by wetting and nonwetting phases for Berea sandstone. The data obtained suggest that the Kozeny-Carman relation and Archie's empirical laws used to predict permeability must be modified to take into account a finite percolation threshold, or impossible values will be returned for the relative permeability of the nonwetting phase.
© 1992 Pergamon Press Ltd. Reproduction not permitted R M M S 29D---K
923180 Spatial and temporal moments of tracer concentration in disordered porous media
Field observations of water, tritium, and bromide movement during infiltration and redistribution at a heavily instrumented and well characterised site are described. Water and bromide moved fairly homogeneously during infiltration, with bromide ahead of tritium due to anion exclusion during redistribution. A two dimensional flow model gave predictions in qualitative agreement with measurements for 2 of the 3 water content measurement planes. Tracer transport was not as well predicted, with localised inhomogeneities and large downward motion of bromide with respect to tritium during redistribution not being reproduced.
Concentration distribution predictions are often required from irregularly sampled measurements. Geostatistical methods are well suited for such tasks. A method to derive the spatial and temporal moments of tracer concentration in a disordered geological medium is developed to allow interpolation and prediction of concentration, conditional to concentration measurements. It is based on a biparticle tracking scheme which yields the bivariate probability distribution function of particle displacements in terms of the input log conductivity random field and the prevailing flow conditions.
923177 Analytical solutions for solute transport in three-dimensional semi-infinite porous media Leij, F J; Skaggs, T H; van Genuchten, M T Water Resour Res V27, NIO, Oct 1991, P2719-2733 Analytical solutions are derived for the three dimensional advection-dispersion equation (ADE) during one dimensional flow in a 3D semi-infinite medium. The transport equation includes terms which account for linear equilibrium adsorption, zero-order production, and first-order decay. The ADE is solved subject to first type (concentration) and third type (flux) boundary conditions at the inlet location of the medium. Analytical solutions are derived using several integral transforms to reduce the partial differential equations to simplified algebraic expressions. Solutions are presented for 5 specific combinations of initial and boundary concentration profiles. 923178 Porous media with linearly variable hydraulic properties
Vogel, T; Cislerova, M; Hopmans, J W Water Resour Res V27, NIO, Oct 1991, P2735-2741 The functional similarity concept (Simmons et ai, 1979) is generalised and extended for the analysis of flow in a system of parallel, homogeneous, one-, two-, or three-dimensional soil profiles. The resulting invariance of Richard's equations for a set of soil profiles is valid for certain initial and boundary conditions only. Direct identification of scaling factors based on measured soil hydraulic properties or indirect identification based on measured dynamic characteristics of the soil water system are described. The concept may be used to classify soils according to the shape of their reference hydraulic properties or describe temporal or spatial variabilities of properties for use in numerical modelling. 923179 Empirical model of intrinsic permeability in reactive dayb e a r ~ snds gaffensperger, J P; Fen'ell, R E Water Resour Res V27, Nll, Nov 1991, 1'2835-2844 Permeability response of clay-containing sands to change in fluid composition has been examined. Tests used solutions of sodium and calcium chloride of different concentrations, plus freshwater flushing of salt-containing sediments and stepwise variation of fluid composition. Sediment specific surface areas and microstructures were studied. A nempirical model of permeability is developed including effects of porosity, mean pore size, and specific surface areas. Differences between measured permeabilities and Kozeny-Carruan predictions using the experimental data may be explained in terms of dead-end pores and large-channel flows.
Rubin, Y Water Resour Res V27, Nil, Nov 1991, P2845-2854
923181
Diffusion-controlled contaminant transport in landflD.elay liner systems Rowe, R K; Booker, J R Proc International Symposium on Computer and Pkydcul Modelling in Geoteclmicul Engineering, Bangkok, 3-6 December 1986 P509-520. Publ Rotterdam: ,4 A Balkema, 1989 This new technique, based on finite layer theory, is applicable to deposits which can be ideaiised as layers, and is not computationally intensive. Two dimensional analysis of a fully stratified deposit can be undertaken. An example investigates effect of physical and chemical parameters and advection velocity on escape of contaminant from a capped landfill. 923182
Effect of percolating structures on the petrophysieal properties of Berea sandstone Agrawal, D L; Cook, N G W; Myer, L R Rock Meclmules as a Multidisciplinary Scieace: Proc 32ad US Symposium, Nornum, 10-12 July 1991 P345-354. Publ Rotterdam: A A Baikema. 1991 The topography and heterogeneity of flow paths in Berea sandstone and Indiana limestone have been studied using Wood's metal porosimetry. Effects of path length and time on percolation were studied. Pore system differences for the two rock types were examined by SEM after the mineral grains had been etched away. The flow of fluid is strongly dependent on the length of the flow path from the free surface. As path length increases, the throats providing the interconnection between larger pores become smaller. The best connected pores become occupied, conductivity to future flow being reduced. 923183
Estimates of permeability and relative permeability m ~ l image analysis of cross sectinm Blair, S C; Berryman, J C Rock Meekames as a Multidiseip~mry ,~ieoce: Proc 32ml US Sympasi~n, Norton, 10-12 July 1991 P365-374. Publ Rotterdam: A A Balkema, 1991 Digitised images of rock cross sections, interpreted using statistical correlation functions, were used to provide information on total porosity and amount of pore space occupied by wetting and nonwetting phases for Berea sandstone. The data obtained suggest that the Kozeny-Carman relation and Archie's empirical laws used to predict permeability must be modified to take into account a finite percolation threshold, or impossible values will be returned for the relative permeability of the nonwetting phase.
© 1992 Pergamon Press Ltd. Reproduction not permitted R M M S 29D---K