The fluid dynamics of propagating fronts with solutal and thermal coupling

Abstract

We numerically explore the propagation of reacting fronts in a shallow and horizontal layer of fluid. We focus on fronts that couple with the fluid due to density differences between the products and reactants and also due to heat release from the reaction. We explore fronts where this solutal and thermal coupling is cooperative or antagonistic. We quantify the fluid motion induced by the front and investigate the interactions of the front with the fluid as it propagates through quiescent, cellular and chaotic flow fields. The solutal coupling induces an extended convection roll that travels with the front, the thermal coupling due to heat release from the reaction generates a pair of convection rolls that travels with the front, and when both couplings are present there is a complex signature of these contributions. The details of the front dynamics depend significantly upon the interactions of the front-induced flow field with the fluid ahead of the front.

Buoyancy-Driven Chemohydrodynamic Patterns in A + B → Oscillator Two-Layer Stratifications

“…These can start convective flows due to localized compositional and temperature variations which, in turn, feed back with the spatiotemporal evolution of the chemical patterns. This active chemo­hydrodynamic loop has been shown to induce self-organized dynamics such as the acceleration and distortion of autocatalytic fronts, − segmented chemical waves, oscillatory behaviors even in the absence of truly oscillatory chemical kinetics (i.e., in autocatalytic fronts and simple A + B → C systems), − and transitions to chemical turbulence and chaos in spatially extended chemical oscillators. − The potential of hydrodynamics in combination with oscillatory kinetics has also been introduced in neuromorphic engineering, chemical artificial intelligence, and chaos computing. , …”

Marangoni-vs.buoyancy-driven flows: competition for spatio-temporal oscillations in A + B → C systems

“…We will focus here on antagonistic cases since the competition between opposite flows has long been known to induce complex dynamics. [30][31][32]35,38,45 3.1 Phenomenology Fig. 1a illustrates the previously studied case (region I) where the production of C, less dense than the reactant solutions, generates a vertical upward flow due to gravitational currents and, concurrently, increases the surface tension, thus inducing a vertically downward Marangoni flow.…”

“…We will focus here on antagonistic cases since the competition between opposite flows has long been known to induce complex dynamics. 30–32,35,38,45…”

“…Convective flows interact, in turn, with the initial RD fronts and new dynamics can develop. 34,35 Both the scenarios in which the reaction induces a flow 35 and when chemical structures like fronts or waves propagate through an established flow field 36–38 have been thoroughly studied.…”

Quantifying the relationship between spreading depolarization and perivascular cerebrospinal fluid flow

“…Previous studies of chemical RD waves in an imposed fluid flow have shown that RD waves can disrupt complex fluid flow through different forms of coupling 26,27 . There are several mechanisms by which SD may disrupt glymphatic flow.…”