On the behavior of approaches to simulate reactive transport

Saaltink, Maarten W.; Carrera, Jesús; Ayora, Carlos

doi:10.1016/s0169-7722(00)00172-8

Cited by 93 publications

(95 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although this standard Eulerian formulation can lead to poor accuracy when simulating the advective-diffusive migration of concentration fronts [Daus et al, 1985], the systems investigated in this work are characterized by rapid gas transport under quasi-steady state conditions with concentration gradients mostly controlled by boundary conditions and geochemical reactions. Under these conditions, Eulerian methods provide adequate accuracy, even for large time steps [Saaltink et al, 2001]. The implementation is unconditionally stable, and in the simulations presented in the next section, no stability issues have appeared.…”

Section: Numerical Implementationmentioning

confidence: 94%

Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study

Molins

Mayer

2007

Water Resources Research

106

View full text Add to dashboard Cite

[1] The two-way coupling that exists between biogeochemical reactions and vadose zone transport processes, in particular gas phase transport, determines the composition of soil gas. To explore these feedback processes quantitatively, multicomponent gas diffusion and advection are implemented into an existing reactive transport model that includes a full suite of geochemical reactions. Multicomponent gas diffusion is described on the basis of the dusty gas model, which accounts for all relevant gas diffusion mechanisms. The simulation of gas attenuation in partially saturated landfill soil covers, methane production, and oxidation in aquifers contaminated by organic compounds (e.g., an oil spill site) and pyrite oxidation in mine tailings demonstrate that both diffusive and advective gas transport can be affected by geochemical reactions. Methane oxidation in landfill covers reduces the existing upward pressure gradient, thereby decreasing the contribution of advective methane emissions to the atmosphere and enhancing the net flux of atmospheric oxygen into the soil column. At an oil spill site, methane oxidation causes a reversal in the direction of gas advection, which results in advective transport toward the zone of oxidation both from the ground surface and the deeper zone of methane production. Both diffusion and advection contribute to supply atmospheric oxygen into the subsurface, and methane emissions to the atmosphere are averted. During pyrite oxidation in mine tailings, pressure reduction in the reaction zone drives advective gas flow into the sediment column, enhancing the oxidation process. In carbonate-rich mine tailings, calcite dissolution releases carbon dioxide, which partly offsets the pressure reduction caused by O 2 consumption.Citation: Molins, S., and K. U. Mayer (2007), Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study, Water Resour. Res., 43, W05435,

show abstract

Section: Numerical Implementationmentioning

confidence: 94%

Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study

Molins

Mayer

2007

Water Resources Research

106

View full text Add to dashboard Cite

show abstract

“…In the sequential non-iterative approach (SNIA), however, only a single solve of the transport and reaction terms is carried out. The other approach, referred to as the global implicit or one-step method, reaction and transport are solved simultaneously [54,57].…”

Section: Approaches For the Reactive Transport Problemmentioning

confidence: 99%

Reactive transport codes for subsurface environmental simulation

et al. 2014

View full text Add to dashboard Cite

A general description of the mathematical and numerical formulations used in modern numerical reactive transport codes relevant for subsurface environmental simulations is presented. The formulations are followed by short descriptions of commonly used and available subsurface simulators that consider continuum representations of flow, transport, and reactions in porous media. These formulations are applicable to most of the subsurface environmental benchmark problems included in this special issue. The list of codes described briefly here includes PHREEQC, HPx, PHT3D, OpenGeoSys (OGS), HYTEC, ORCHESTRA, TOUGHREACT, eSTOMP, HYDROGEOCHEM, CrunchFlow, MIN3P, and PFLOTRAN. The descriptions include a C. I. Steefel ( ) · B. Arora · S. Molins · N. Spycher

show abstract

“…The connection with transport was tested for a situation of fracture within calcareous rock, entered by water which was under-saturated with respect to calcite. Such a system was studied by Saaltink et al (2001). Some parameter values were adopted from that study.…”

Section: Transport and Speciationmentioning

confidence: 99%

“…The values proposed by Saaltink et al (2001) are provided in Table 8.4. The kinetic transfer coefficient a varies over 4 orders of magnitude.…”

Section: Transport and Speciationmentioning

confidence: 99%

Transport and Equilibrium Reactions

Holzbecher¹

2011

Environmental Modeling

View full text Add to dashboard Cite

The situation that environmentally relevant species take part in chemical reactions, while being transported through a compartment of the environment, was already treated in Chap. 7. In this chapter the same situation is taken up again with the difference concerning the time scale of the reactions. Here we deal with reactions which are fast in comparison to transport processes.The situation that chemical reactions are fast compared to other environmental processes is met quite often but on very different time scales. The scale difference is related to the fact that the transport time scale deviates significantly in different compartments. There are systems which are almost in a no-flow state. In deep underground reservoirs transport is measured in geological time scales, and most chemical transformations can be assumed to be fast in comparison. In near-surface aquifers velocities are often in the range of several meters per year or higher, and some chemical processes may not reach their equilibrium. Sedimentation rates in the deep ocean or in lakes are in the order of several mm per year; this sets the scale for fast and slow reactions in those systems. Therefore, each environmental compartment has its own time-scale and is related to chemical processes in a different manner.Reactions with a characteristic time, which is in the same scale as transport or even slower, can be included in the mathematical description as shown in the previous chapter. The reaction rate has to be formulated in dependence of concentrations and maybe some other state variables, like temperature, and added as another term in the differential equation. As the reaction contributes to the mass balance, which is expressed by the differential equation, the mathematical formulation is straight forward. More difficult is the determination of rate expressions that are relevant in practice from the chemical point of view. But this has to be left to chemists and is outside of the scope of this book.For fast reactions, the rate law is not relevant. Instead, the equilibrium characteristic is brought into play. A widely accepted formulation is given by the law of E. Holzbecher, Environmental Modeling,

show abstract

On the behavior of approaches to simulate reactive transport

Cited by 93 publications

References 26 publications

Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study

Coupling between geochemical reactions and multicomponent gas and solute transport in unsaturated media: A reactive transport modeling study

Reactive transport codes for subsurface environmental simulation

Transport and Equilibrium Reactions

Contact Info

Product

Resources

About