EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effect of non-uniform passive advection on A+B->C radial reaction-diffusion fronts 

Alessandro Comolli, Anne De Wit, and Fabian Brau
Alessandro Comolli et al.
  • Nonlinear Physical Chemistry Unit, Université libre de Bruxelles (ULB), Brussels, Belgium

The interplay between chemical and transport processes can give rise to complex reaction fronts dynamics, whose understanding is crucial in a wide variety of environmental, hydrological and biological processes, among others. An important class of reactions is A+B->C processes, where A and B are two initially segregated miscible reactants that produce C upon contact. Depending on the nature of the reactants and on the transport processes that they undergo, this class of reaction describes a broad set of phenomena, including combustion, atmospheric reactions, calcium carbonate precipitation and more. Due to the complexity of the coupled chemical-hydrodynamic systems, theoretical studies generally deal with the particular case of reactants undergoing passive advection and molecular diffusion. A restricted number of different geometries have been studied, including uniform rectilinear [1], 2D radial [2] and 3D spherical [3] fronts. By symmetry considerations, these systems are effectively 1D.

Here, we consider a 3D axis-symmetric confined system in which a reactant A is injected radially into a sea of B and both species are transported by diffusion and passive non-uniform advection. The advective field vr(r,z) describes a radial Poiseuille flow. We find that the front dynamics is defined by three distinct temporal regimes, which we characterize analytically and numerically. These are i) an early-time regime where the amount of mixing is small and the dynamics is transport-dominated, ii) a strongly non-linear transient regime and iii) a long-time regime that exhibits Taylor-like dispersion, for which the system dynamics is similar to the 2D radial case.


                                                   Fig. 1: Concentration profile of the product C in the transient (left) and asymptotic (right) regimes.



[1] L. Gálfi, Z. Rácz, Phys. Rev. A 38, 3151 (1988);

[2] F. Brau, G. Schuszter, A. De Wit, Phys. Rev. Lett. 118, 134101 (2017);

[3] A. Comolli, A. De Wit, F. Brau, Phys. Rev. E, 100 (5), 052213 (2019).

How to cite: Comolli, A., De Wit, A., and Brau, F.: Effect of non-uniform passive advection on A+B->C radial reaction-diffusion fronts , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5697,, 2021.

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