Convection flows driven by laser heating of a liquid layer

Area of Science:

• Physics
• Fluid Dynamics
• Optics

Background:

• Laser absorption in fluids causes localized heating and density reduction.
• Density gradients induce pressure gradients, initiating fluid flow.
• Mass conservation principles lead to the formation of convection eddies.

Purpose of the Study:

• To investigate laser-driven bulk fluid flows at the microscopic scale.
• To characterize the relationship between laser power and fluid dynamics.
• To explore the transition between thin and thick liquid layer regimes.

Main Methods:

• Experimental setup for temperature measurements using fluorescent-sensitive dye.
• Particle image velocimetry (PIV) for flow pattern analysis at varying beam powers.
• Numerical simulations incorporating experimental temperature data for velocity profile comparison.

Main Results:

• Detailed description of convection flows induced by light absorption.
• Identification of a transition between thin and thick liquid layer regimes.
• Validation of numerical predictions against experimental velocity profiles.

Conclusions:

• The study provides a comprehensive understanding of laser-induced microfluidic convection.
• The findings support the foundation for optothermal approaches in microfluidics.
• The observed regime transition is a key characteristic of these laser-driven flows.