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Introducing boundary-layer (BL) theory to solve problems of solute transport provides a simple and accurate alternative method to estimate transport parameters. Most BL solutions to the convection–...

International audience; It is established that solute transport in homogenous porous media follows a classical ’S’ shape breakthrough curve that can easily be modelled by a convection dispersion equation. In this study, we designed a Model Heterogeneous Porous Medium (MHPM) with a high degree of heterogeneity, in which the breakthrough curve does not follow the classical ’S’ shape. The contrast in porosity is obtained by placing a cylindrical cavity (100% porosity) inside a 40% porosity medium composed with 1mm glass beads. Step tracing experiments are done by injecting salty water in the study column initially containing deionised water, until the outlet concentration stabilises to the input one. Several replicates of the experiment were conducted for n = 1 to 6 MHPM placed in series. The total of 116 experiments gives a high-quality database allowing the assessment of experimental uncertainty. The experimental results show that the breakthrough curve is very different from the ’S’ shape for small values of n, but the more n increases, the more the classical shape is recovered.

Concern about the transport of chemicals in groundwater systems has stimulated the development of many models to describe transport in porous media, the most common of which under steady-state cond...

The convection-dispersion equation (CDE) is the classical approach for modeling solute transport in porous media. So, estimating parameters became a key problem in CDE. For statistical method, some problems such as parameter uniqueness are still unsolved because of more factors. Due to the advantage of clear physical concept and unique parameter values, the simple deterministic method became very useful alternatives. In this paper, a simple method was proposed to estimate both D and R, and the validity was verified by experiment, which can be applied in agriculture and environmental fields for predicting soil quality property.Key words: Convection-dispersion equation (CDE), parameters estimation, agricultural system.

The one-dimensional convection-dispersion equation subject to a nonlinear adsorption isotherm is formulated and solved by using a predictor-corrector finite difference scheme. The effects of convection, dispersion, and adsorption are illustrated for some typical values of variables encountered in ‘real systems.’ A comparison between the numerical results and some experimental data is also presented.

Using the theory of volume averaging, we have shown1 that molecular diffusion, mass tortuosity, and mechanical mixing contribute to the mass-dispersion coefficient. A series of experiments were conducted on the system Triton X-100TM surfactant, n-decane oil, and water to determine the contribution of each mechanism to the total-dispersion matrix for flow through fired Berea sandstone. The dynamics of adsorption and the effect of dead-space volume are considered for the single-phase transport of surfactant through fired Berea. A new dynamic asdorption model is developed which considers both mass transfer to the fluid/solid surface and a kinetic surface-adsorption mechanism. Both kinetic adsorption and mass-transfer rate mechanisms are shown to be important over a wide range of injection rates.