Experimental methods for visualization of hydrodynamic instability caused by the neutralization reaction in a miscible two-layer system

Elena Mosheva,P Dančová,J Novosad

doi:10.1051/epjconf/201921302060

Elena Mosheva, P Dančová + Show 1 more

Open Access

https://doi.org/10.1051/epjconf/201921302060

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Abstract

This paper focuses on experimental investigations of the spatio-temporal distributions of fluid velocity and temperature and the concentration of reagents and reaction products. We study concentration-dependent diffusion (CDD) convection driven by the neutralization reaction in a two-layer miscible system in a vertical Hele-Shaw cell using the original experimental complex. A comprehensive understanding of the physical mechanisms of convective motion and instabilities requires employing various experimental methods simultaneously. The proposed experimental complex provides simultaneous visualization and facilitates identification of the location of the reaction front, which is of importance to the study of its characteristics.

Highlights

Investigation of the chemo-hydrodynamic patterns is necessary for studying heat and mass transfer processes, hydrodynamic instability mechanisms and convective flow structure and its evolution in a two-layer system of reacting fluids
The concentrationdependent diffusion (CDD) convection patterns visualized using the above described experimental complex are given in figure 2
The first row represents the initial stage of the CDD instability formation (300 seconds after the reagents come into contact)

Summary

Introduction

Investigation of the chemo-hydrodynamic patterns is necessary for studying heat and mass transfer processes, hydrodynamic instability mechanisms and convective flow structure and its evolution in a two-layer system of reacting fluids. Due to the fact that the diffusion coefficients of reagents depend on the concentration of solutions, the density profile may drastically change in time, which was not taken into account in the proposed classification. It was shown both experimentally and theoretically that concentrationdependent diffusion coupled with frontal acid-base neutralization reaction can produce a spatially localized zone with unstable density stratification which, under gravity, gives rise to the onset of the instability called concentration-dependent diffusion convection (CDD convection) [4]

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