Excitation of fountain and entrainment instabilities at the interface between two viscous fluids using a beam of laser light

TL;DR

This paper investigates laser-driven instabilities at the interface of two viscous fluids, revealing how laser beam parameters influence interface deformation and jet formation through experimental and numerical methods.

Contribution

It introduces and characterizes two novel laser-induced interface instabilities, providing insights into their dependence on laser beam waist and flow dynamics.

Findings

Interface deformation height depends on laser beam waist

Jet radius after destabilization is influenced by beam parameters

Distinct behaviors of fountain and entrainment instabilities are identified

Abstract

We report on two instabilities called viscous fountain and viscous entrainment triggered at the interface between two liquids by the action of bulk flows driven by a laser beam. These streaming flows are due to light scattering losses in turbid liquids, and can be directed either toward or forward the interface. We experimentally and numerically investigate these interface instabilities and show that the height and curvature of the interface deformation at the threshold and the jet radius after interface destabilization mainly depend on the waist of the laser beam. Analogies and differences between these two instabilities are characterized.