DrLiShen

Summary

I am an EPSRC Post-doctoral Research Fellow working on the dynamics of bubbles in the Tribology Group, Department of Mechanical Engineering, Imperial College London.

I take photographs of bubbles at different lengthscales and construct models to describe them, some mathematical, some computational, some molecular computational. 

I completed my PhD in the Tribology Group under the supervision of Prof. Daniele Dini in 2018 on the "Symmetry-breaking pattern formation in thin films with application to foaming in viscous fluids" and was awarded an EPSRC Impact Acceleration Account during my post-doc (2019-21) to work on experimental quantitative foaming techniques. 

Research interests 

My research interests include all aspects of fluid dynamics of the bubble and thin liquid films, but more specifically: 

Pattern formation on bubbles. With components of diffusion and advection on the thin film interface, Turing-esq patterns can be detected at certain lengthscales and stages of film drainage. Combining asymptotic and experimental methods, I aim to classify the various (Marangoni-induced symmetry-breaking) pattern formations on the bubble in order to understand how contamination can change these patterns, which often occur just before the onset of film rupture. 

Capillary waves on bubbles. I study the capillary waves on the liquid interface. These fluctuations often reveals intrinsic behaviours about the system which can be used as an indicator towards more complex behaviours such as pattern formation or rupture phenomena. Recent work incorporates the Marangoni effect and surface viscosity within the capillary wave framework. 

Molecular dynamics of bubbles. Looking at the Marangoni effect at the molecular scale involves deriving the basic fluid dynamics equation atomistically. I study the interplay between the molecular interface transport and gradients of surface tension with the aim to improve continuum mechanics models on transport that takes into account different species of contamination on the interface.  

Coarsening and scaling law behaviours in foam collapse. Foam is a complex superstructure with a vast collection of behaviours occurring at each layer of liquid fraction (as pictured below). The collective behaviour of foam collapse is stochastic in nature but follows (experimentally) very precise scaling laws. I aim to study this coarsening-related behaviour which deviates from the standard LSW coarsening laws.

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