Comparison of (a)–(l) 40nm spherical nanobubble, (m)–(r) high contact angle (HCA) surface nanobubble, and (s)–(x) low contact angle (LCA) surface nanobubble, collapsing near a amorhpous silicon substrate.
Nanobubble Cavitation Dynamics (2016-)

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

Comparison of solid ice structure (above) with melting ice due to surface vibrations (below).
Surface de-icing/anti-icing by acoustothermal effect (2018-)

Ice formation not only influences our daily life in various scenarios, ranging from ice accumulation in the freezer to the accretion of ice on the windscreen of a car, but also has effects on global phenomena like climate change. Ice formation is desirable in many applications such as artificial cloud creation, preservation of biological substances, and food transportation. On the other hand, icing can lead to a loss of life by hindering the operational performance of instrumentation or navigation systems on aircraft, ships, and helicopters; Icing can also damage power lines and telecommunications equipment; reduce the energy efficiency of wind turbines, and hinder operational performance. Therefore, control of ice formation is of crucial importance in various industrial sectors.

Recent investigations have unraveled a novel surface-driven acoustothermal force which can superheat fluid within a few nanometres of the vibrating surface. The magnitude of this superheat can be tuned externally, so this provides a new capability to delay icing and/or melt formed ice. This project investigates how the chemical and structural properties of the surface, along with the applied acoustic parameters, impact the heating and melting dynamics during vibration.

This work is being conducted by Saikat.

Academic(s) involved: Rohit and Matthew

Comparison of Inertio-Thermal (IT) model predictions with the inertial Rayleigh-Plesset equation (RP), the MRG model, and MD results.
Inertio-Thermal Vapor Bubble Growth (2019-)

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