Photothermal nanobubble nucleation on a plasmonic nanoparticle: A 3D lattice Boltzmann simulation

Abstract

Nanobubble nucleation by plasmonic heating on a gold spherical nanoparticle under laser illumination is numerically investigated by a 3D liquid-vapor phase change lattice Boltzmann (LB) method. A volumetric heat source is incorporated to the evolution equation of temperature distribution function to simulate photothermal energy conversion effect in a plasmonic gold spherical nanoparticle induced by surface plasma resonance under laser illumination. A halfway bounce-back conjugate boundary condition on nanoparticle/liquid interface for LB simulation, with interfacial thermal resistance taken into consideration, is derived. It is confirmed that nanobubble nucleates on a laser heated hydrophilic gold spherical nanoparticle in a core-shell mode under normal gravity condition. To simulate nanobubble nucleation on a plasmonic nanoparticle in a spherical cap mode, an extraordinary (fictitious) hyper gravity environment would have to be imposed. Effects of nanoparticle surface’s wettability, nanoparticle-liquid interfacial thermal resistance, and nanoparticle’s diameter on nanobubble nucleation under normal gravity are investigated. The size of the nanoparticle is found to have non-monotonic effects on the threshold laser fluence of nanobubble nucleation, with the 60 nm gold nanoparticle having the lowest threshold laser fluence for nucleation. This finding is in agreement with existing experimental results.