Enhanced convective dissolution due to an A + B → C reaction: control of the non-linear dynamicsviasolutal density contributions

Abstract

Chemical reactions can have a significant impact on convective dissolution in partially miscible stratifications in porous media and are able to enhance the asymptotic flux with respect to the non-reactive case.

Chemo-Hydrodynamic Patterns and Instabilities

“…Only, when the reaction front has traveled a while downward is then merging towards a new larger fixed wavelength obtained ( Figure 10d). In all reactive cases, the convective flux of A into the host phase is larger than in the non reactive case (Loodts et al (2017), Jotkar et al (2019)). The case of reversible reactions and additional viscosity contrasts has also been tackled, showing even more complex scenarios when C can revert to the reactants once formed (Alhumade & Azaiez (2015)).…”

“…In the stabilizing case (c), the non-monotonic density profile with a minimimum is giving a density barrier inducing regular fingers with a constant wavelength in time. As seen on the corresponding space-time map (d), these fingers rearrange after a while to yield a new "frozen" pattern but with a larger wavelength (Loodts et al (2017), Jotkar et al (2019).…”

“…While simple reactions consuming A out of the solution stabilize convection (Ghesmat et al (2011), Andres & Cardoso (2011, Cardoso & Andres (2014), Ward et al 2014, Kim & Choi (2014), Kim & Kim (2015), Ghoshal et al (2018)), various theoretical works have shown that A+B→C reactions can accelerate or decelerate the convective dynamics with respect to the nonreactive case and that the steady-state dissolution flux of species A varies with the difference ∆RCB (Loodts et al (2014(Loodts et al ( , 2015(Loodts et al ( , 2017(Loodts et al ( , 2018, Jotkar et al (2019), Ghoshal et al (2017).) For equal diffusion coefficients, if ∆RCB > 0, the density profiles are monotonic.…”

“…Figure 9: Classification of dimensionless density profiles in the parameter space (β = b0/a0, ∆RCB = RC − RB), developing when a species A dissolves at z = 0 downwards into a host phase containing a species B and reacts according to the A+B→C scheme to generate the product C (Loodts et al (2016(Loodts et al ( , 2015, Jotkar et al (2019)).…”

“…The upper part of the profile features density decreasing along gravity which is prone to trigger convection. However, this zone is followed downwards by a stabilizing density barrier that constrains the fingers in a localized zone of space (Loodts et al (2018), Jotkar et al (2019), Budroni et al (2014). The resulting nonlinear dynamics can be quite different: in the destabilizing case, long sinking fingers are formed which regularly merge while new fingers appear at the boundary (Figure 10a).…”