Dr. Duncan Dockar

I am a postdoctoral research associate in mfX, running particle (MD, DEM) simulations. I obtained my MEng and PhD in Mechanical Engineering from the University of Edinburgh, in 2016 and 2020, respectively. My doctoral research was concerned with the cavitation dynamics of surface nanobubbles, a type of spherical cap-shaped bubble which are pinned to solid surfaces, with remarkable stability against dissolution and unstable growth. During my PhD, I outlined a typical cavitation event of a surface nanobubble: first I determined the minimum pressure, or cavitation threshold, required to induce unstable growth of a surface nanobubble. Then I modelled their oscillation dynamics, predicting their natural frequency, during this rapid growth phase. Finally, I modelled their violent collapse, enhanced by shock-waves, in which high-speed jets that develop during their collapse create pitting damage in the underlying substrate. In each case, I demonstrated that surface nanobubbles behaved differently to spherical (bulk) nanobubbles, due to their spherical cap shape and pinned contact line, and provided alternative models to predict their cavitation dynamics.

In my current post-doctoral role, I balance multiple projects, one in collaboration with Dr Kokou Dadzie and Prof Raffaella Ocone at Heriot-Watt University, modelling dilute granular flows using modified hydrodynamic equations for fine particle control, and comparing with Discrete Element Method (DEM) simulations. I am also continuing my research into nanobubbles, using Molecular Dynamics (MD) simulations to model how dominant fluid phenomena at the nanoscale, such as non-equilibrium gas dynamics, viscosity, and surface tension, significantly alter the cavitation dynamics of these nanobubbles, as compared to macro scale bubbles.


Shock-induced collapse of surface nanobubbles
Forced oscillation dynamics of surface nanobubbles
Mechanical Stability of Surface Nanobubbles