Solute transport through porous media using asymptotic dispersivity

Abstract

In this paper, multiprocess non-equilibrium transport equation has been used, which accounts for both physical and chemical non-equilibrium for reactive transport through porous media. An asymptotic distance dependent dispersivity is used to embrace the concept of scale-dependent dispersion for solute transport in heterogeneous porous media. Semi-analytical solution has been derived of the governing equations with an asymptotic distance dependent dispersivity by using Laplace transform technique and the power series method. For application of analytical model, we simulated observed experimental breakthrough curves from 1500 cm long soil column experiments conducted in the laboratory. The simulation results of breakthrough curves were found to deviate from the observed breakthrough curves for both mobile-immobile and multiprocess non-equilibrium transport with constant dispersion models. However, multiprocess non-equilibrium with an asymptotic dispersion model gives better fit of experimental breakthrough curves through long soil column and hence it is more useful for describing anomalous solute transport through heterogeneous porous media. The present model is simpler than the stochastic numerical method.

Dispersion of pollutants in a porous medium with finite thickness and variable dispersion coefficients

“…A semi-analytical solution of the transport model with an asymptotic dispersion depending on the distance and on the asymptotic dispersivity parameters (a), and on the half-length characterizing the mean stroke (b), was developed by Sharma and Abgaze, (2015) taking into account a condition of zero pollutant concentration at the outlet of the domain and parameters of constant asymptotic dispersivity in a homogeneous porous medium. This author neglected certain boundary conditions that may occur at the aquifer boundary due to natural phenomena, as mentioned in the works of Al-Niami and Rushton, (1976);Yadav et al (2012) and the variability of the asymptotic dispersivity parameters in a heterogeneous porous medium.…”

“…Three initials concentration injection condition were introduced at the inlet of the aquifer : (a)constants, (b) variables exponentially with time and (c) sinusoidally with time. This article proposes a numerical solution of the transport model with an asymptotic dispersion dependent on the distance with the parameters of asymptotic dispersivity (a), and the half-length characterizing the mean stroke (b) developed by Sharma and Abgaze (2015), by taking two conditions at the outlet of the domain and a variable asymptotic dispersion parameters a and b in a heterogeneous porous medium.…”

Long-term assessment, modeling and forecast of salinity conditions of reclaimed mine dumps of Western Donbass

“…The fate of chemical substances in the soil is complex and dynamic, depending on such factors as clay level, soil pH, hydraulic conductivity, structure, and many others [3]. From the general convection-dispersion function describing solute transport in porous media, several numerical and analytical models have evolved [4,5]. These include the finite difference approaches.…”

Non-Fickian dispersivity investigation from numerical simulations of tracer transport in a model double-porosity medium at different saturations

“…A general consensus about the scale-dependent dispersivity has been reported by many laboratory and field researches over the last few decades (Silliman and Simpson, 1987;Gelhar et al, 1992;Irwin et al, 1996;Pachepsky et al, 2003;Huang et al, 2006, among others). It means that during solute transport in heterogeneous media the dispersivity increases with travel distance (thus with time) in a pre-asymptotic stage before reaching a constant value (Gelhar, 1987;Mishra and Parker, 1990; Suresh Kumar et al, 2006;Sharma and Abgaze, 2015). Irwin et al (1996) showed that dispersion may be dependent upon the scale of a characteristic length (travel distance) from their KCl tracer transport experiment in a medium with periodic heterogeneity.…”