Nanobubbles are being applied in cancer treatment, surface cleaning, sonochemistry, and water treatment, for break-down and removal of particles/cells and enhanced chemical reactions. Central to these applications is their cavitation dynamics, or how they respond under rapid variations in pressure, for example under ultrasound irradiation. Conventional cavitation models for macroscale bubbles typically fail at the nanoscale due to heterogeneous surface pinning effects, high-density non-ideal gas behaviour, rarefied gas dynamics, and other atomic-level phenomena. In this research, we investigate the suitability of these classical models for pinned surface nanobubbles and bulk nanobubbles, and derive new theoretical models to explain their often anomalous behaviour.

This work is being conducted by Duncan.

Academic(s) involved: Livio and Matthew

Our understanding of vapour bubble growth is currently restricted to asymptotic descriptions of their limiting behaviour. While attempts have been made to incorporate both the inertial and thermal limits into bubble growth models, the early stages of bubble growth have not been captured. This project accounts for both the changing inertial driving force and the thermal restriction to growth, and aims to develop inertio-thermal models of homogeneous/heterogeneous vapour bubble growth, capable of accurately capturing the evolution of a bubble from the nano- to the macro-scale. Model predictions are validated against: a) published experimental and numerical data, and b) our own molecular simulations. This has potential application in improving the performance of engineering devices, such as ultrasonic cleaning and microprocessor cooling, as well as in understanding of natural phenomena involving vapour bubble growth.

This work is being conducted by Patrick.

Academic(s) involved: Rohit and Matthew