Thermocapillary flows and interface deformations produced by localized laser heating in confined environment

TL;DR

This paper analytically investigates how localized laser heating induces thermocapillary flows and deformations at fluid-fluid interfaces within confined environments, highlighting the influence of viscosities and layer thicknesses.

Contribution

It provides a theoretical analysis of interface deformation due to thermocapillary stresses in confined fluids, considering different layer configurations and their dependence on physical parameters.

Findings

Deformation direction depends on viscosities and layer thicknesses.

Analytical expressions predict interface behavior under localized heating.

Results applicable to optofluidic applications.

Abstract

The deformation of a fluid-fluid interface due to the thermocapillary stress induced by a continuous Gaussian laser wave is investigated analytically. We show that the direction of deformation of the liquid interface strongly depends on the viscosities and the thicknesses of the involved liquid layers. We first investigate the case of an interface separating two different liquid layers while a second part is dedicated to a thin film squeezed by two external layers of same liquid. These results are predictive for applications fields where localized thermocapillary stresses are used to produce flows or to deform interfaces in presence of confinement, such as optofluidics.