Condensation induced internal convection of two neighboring droplets

TL;DR

This study explores how two neighboring condensing droplets influence each other's internal flow patterns through vapor-mediated interactions, revealing asymmetric convection patterns driven by solute concentration variations.

Contribution

It demonstrates the impact of neighboring droplets on internal convection during condensation, highlighting asymmetric flow patterns caused by vapor interactions without physical contact.

Findings

Neighboring droplets induce asymmetric internal flow patterns.

The influence of the neighbor decreases with increased separation distance.

Flow patterns during condensation are opposite to those during evaporation.

Abstract

The present work investigates the internal flow structure of two condensing droplets of aqueous solution during interaction. The velocity of fluid inside the droplets was investigated by confocal micro-PIV technique. Condensation on the droplets was carried out inside a closed chamber by creating a difference in vapor pressure between the droplet interface and a reservoir fluid surrounding the droplet in the room temperature without any cooling. Condensation on the droplet leads to spatial variation of solute concentration inside the droplet causing buoyancy driven Rayleigh convection. Fluid flow pattern inside a single condensing droplet is symmetric in nature where as the fluid flow pattern for two interacting droplets is asymmetric in nature. The neighboring droplet influences the internal convection through vapor mediated interaction between the two condensing droplets. Here, the condensing droplet senses the neighboring droplet from a distance without any physical contact. The asymmetric nature of the flow pattern is attributed to the modification in the distribution of condensation flux of the droplet in the presence of the neighboring droplet. The flow pattern observed for interacting droplets during condensation is opposite to that of evaporating droplets. The effect of the neighboring droplet on the internal convection of the condensing droplet reduces with increase in separation distance between the droplets.