Extended classification of the buoyancy-driven flows induced by a neutralization reaction in miscible fluids. Part 1. Experimental study

Abstract

Abstract

Pattern Formation in Miscible Rotating Hele-Shaw Flows Induced by a Neutralization Reaction

“…We have shown in Mizev et al (2021); Bratsun et al (2021) that the neutralization reaction, coupled with the concentration-dependent diffusion, can result in a potential well and can maintain it for a long time in a quasi-steady state. Being under the influence of an external inertial field, a system with such a feature of the density field can demonstrate completely new pattern formation scenarios.…”

“…And since the magnitude of the fluid velocity is a fundamentally important component of the Coriolis force, the Hele-Shaw approximation significantly weakens this force. Let us estimate the Taylor and Rayleigh numbers, which determine the intensity of the Coriolis and centrifugal forces, respectively, for a typical Hele-Shaw cell, which we used in an experimental study presented in Mizev et al (2021):…”

“…One can interpret this term as the average friction force due to the presence of the plates. We can learn from the experimental observations made in the static gravity field Mizev et al (2021) that at the very beginning of evolution ( t < 200 s), the characteristic size of structures can be small enough and the velocity diffusion represented by the Brinkman term can play an important role in the system dynamics. At later…”

“…We should notice that a significant part of the fluid flow dynamics is localized near the reaction front and, in some cases, propagates along with the computational domain. The wavelengths of various instabilities that can potentially develop in the system under consideration are discussed in Mizev et al (2021); Bratsun et al (2021) in detail. Near the axis of rotation, the liquid is in conditions close to weightlessness.…”

“…Besides, in , we have formulated a new dimensionless parameter, the number of reaction-induced buoyancy, which defines the occurrence of new modes of chemoconvection. A complete description of the processes in a two-layer miscible system of two reacting fluids under static gravity was given in two recent works Mizev et al (2021); Bratsun et al (2021). This convective system under static gravity g are characterised by the set of solutal Rayleigh number R i defined as where i is the solutal expansion coefficient for i-species (i stands for any of three concentrations of acid A, base B, and salt C), is the kinematic viscosity of solvent (water), D A0 is the tabular value of the diffusion coefficient of the leading reactant (acid), and A * is the characteristic concentration difference of acid.…”