Winter 2021

Abstract: Understanding the behaviour of liquid-gas interfaces at the micro and nano scale is key to a myriad of phenomena, ranging from the formation of clouds through to 3D printing. Accurate experimental observation of such phenomena is complex due to the small spatio-temporal scales of interest and, consequently, mathematical modelling and computational simulation become key tools with which to probe such flows. As the characteristic scales of interest become comparable to microscopic scales, for a gas the mean free path and for a liquid the molecular diameter, the basic Navier-Stokes-Fourier (NSF) paradigm no longer provides an accurate description of the flow physics. However, microscopic models such as the kinetic theory of gases or molecular dynamics (MD) of liquids become computationally intractable for many flows of practical interest. The majority of my talk will consider the influence of thermal fluctuations, which are seen to be key to understanding counter-intuitive phenomena in nanoscale interfacial flows. A `top down’ framework that incorporates thermal noise is provided by fluctuating hydrodynamics and in this talk we shall use this model to gain insight into free surface nanoflows such as drop coalescence, jet breakup and thin film rupture, using MD as a benchmark. If time permits, I will overview our work on capturing gas kinetic effects to predict the outcome of collision events in which gas nanofilms govern flow behaviour on much larger (mm) scales. Specifically, I will consider the impact of liquid drops on solid surfaces, where we can compare computational models to recent experimental data.