Highly focused supersonic microjets: numerical simulations

TL;DR

This paper uses numerical simulations to analyze the formation of highly focused supersonic microjets generated by laser-induced vapor bubbles in liquids, providing insights into their dynamics and velocity prediction.

Contribution

It introduces an axisymmetric boundary-integral simulation approach and an analytical model to predict microjet velocity, aligning well with experimental observations.

Findings

Simulations match experimental jet evolution

Analytical model accurately predicts jet velocity

Pressure pulse modeling captures jet formation dynamics

Abstract

By focusing a laser pulse inside a capillary partially filled with liquid, a vapour bubble is created which emits a pressure wave. This pressure wave travels through the liquid and creates a fast, focused axisymmetric microjet when it is reflected at the meniscus. We numerically investigate the formation of this microjet using axisymmetric boundary-integral simulations, where we model the pressure wave as a pressure pulse applied on the bubble. We find a good agreement between the simulations and experimental results in terms of the time evolution of the jet and on all parameters that can be compared directly. We present a simple analytical model that accurately predicts the velocity of the jet after the pressure pulse and its maximum velocity.