Autocatalytic plume pinch-off

TL;DR

This paper studies the complex dynamics of autocatalytic plumes driven by chemical reactions, focusing on the phenomenon of plume head pinch-off, using experiments with glycerol solutions and numerical simulations.

Contribution

It provides new insights into the pinch-off behavior of autocatalytic plumes, linking flow acceleration to pinch-off through combined experimental and simulation approaches.

Findings

Pinch-off occurs only within specific glycerol concentration ranges.

Accelerating flow in the conduit triggers plume head pinch-off.

Multiple plume head generations can occur from a single initiation.

Abstract

A localized source of buoyancy flux in a non-reactive fluid medium creates a plume. The flux can be provided by either heat, a compositional difference between the fluid comprising the plume and its surroundings, or a combination of both. For autocatalytic plumes produced by the iodate-arsenous acid reaction, however, buoyancy is produced along the entire reacting interface between the plume and its surroundings. Buoyancy production at the moving interface drives fluid motion, which in turn generates flow that advects the reaction front. As a consequence of this interplay between fluid flow and chemical reaction, autocatalytic plumes exhibit a rich dynamics during their ascent through the reactant medium. One of the more interesting dynamical features is the production of an accelerating vortical plume head that in certain cases pinches-off and detaches from the upwelling conduit. After pinch-off, a new plume head forms in the conduit below, and this can lead to multiple generations of plume heads for a single plume initiation. We investigated the pinch-off process using both experimentation and simulation. Experiments were performed using various concentrations of glycerol, in which it was found that repeated pinch-off occurs exclusively in a specific concentration range. Autocatalytic plume simulations revealed that pinch-off is triggered by the appearance of accelerating flow in the plume conduit.