Micro-droplet nucleation through solvent exchange in a turbulent buoyant jet

Abstract

Solvent exchange is a process involving mixing between a good solvent with dissolved solute and a poor solvent. The process creates local oversaturation which causes the nucleation of minute solute droplets. Such ternary systems on a macro-scale have remained unexplored in the turbulent regime. We experimentally study the solvent exchange process by injecting mixtures of ethanol and trans-anethole into water, forming a turbulent buoyant jet in upward direction. Locally, turbulent mixing causes oversaturation of the trans-anethole following turbulent entrainment. We optically measure the concentration of the nucleated droplets using a light attenuation technique and find that the radial concentration profile is sub-Gaussian. In contrast to the entrainment-based models, the spatial evolution of the oversaturation reveals continuous droplet nucleation downstream and radially across the jet, which we attribute to the limited mixing capacity of the jet. Though we are far from a full quantitative understanding, this work extends the knowledge on solvent exchange into the turbulent regime, and brings in a novel type of flow, broadening the scope of multicomponent, multiphase turbulent jets with phase transition.

arXiv commentWith a new appendix to document the latest experimental interpretation. Accepted manuscript by Journal of Fluid Mechanics

References in corpus (5)

• Extended lifetime of respiratory droplets in a turbulent vapour puff and its implications on airborne disease transmission
• Formation of surface nanodroplets under controlled flow conditions
• Microdroplets nucleation by dissolution of a multicomponent drop in a host liquid
• Solvent Exchange in a Hele-Shaw Cell Universality of Surface Nanodroplet Nucleation
• Universality in microdroplet nucleation during solvent exchange in Hele-Shaw like channels