Unified framework for laser-induced transient bubble dynamics within microchannels

Journal article (2024)

Authors

Nagaraj Nagalingam Complex Fluid Processing - Mechanical, Maritime and Materials Engineering
V.B. Korede Complex Fluid Processing - Mechanical, Maritime and Materials Engineering
D. Irimia Complex Fluid Processing - Mechanical, Maritime and Materials Engineering
J. Westerweel Fluid Mechanics - Mechanical, Maritime and Materials Engineering
J.T. Padding Complex Fluid Processing - Mechanical, Maritime and Materials Engineering
Remco Hartkamp Complex Fluid Processing - Mechanical, Maritime and Materials Engineering
H.B. Eral Complex Fluid Processing - Mechanical, Maritime and Materials Engineering
Research Group
Complex Fluid Processing (Mechanical, Maritime and Materials Engineering) (TU Delft)
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Published Date

2024

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Complex Fluid Processing

Abstract

Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced cavitation bubble, we associate the dynamic bubble size (fluid velocity) and bubble lifetime to the laser energy supplied—a control parameter in experiments. Employing different channel cross-section shapes, sizes and lengths, we demonstrate the characteristic scales for velocity, time and energy to depend solely on the channel geometry. Contrary to the generally assumed absence of instability in low Reynolds number flows (<1000), we report a momentary flow distortion that originates due to the boundary layer separation near channel walls during flow deceleration. The emergence of distorted laminar states is characterized using two stages. First the conditions for the onset of instabilities is analyzed using the Reynolds number and Womersley number for oscillating flows. Second the growth and the ability of an instability to prevail is analyzed using the convective time scale of the flow. Our findings inform rational design of microsystems leveraging pulsatile flows via cavitation-powered microactuation.