My PhD research was under the tutelage of Yulii Shikhmurzaev, who developed the interface formation model (IFM). This theory generalises the classical fluid mechanical boundary conditions to capture the physics of forming and disappearing interfaces, resulting in the interface having a variable surface tension that relaxes to its usual equilibrium value over some characteristic time scale. This model enables one to remove singularities inherent in the classical model for a number of flows including dynamic wetting, drop coalescence and breakup.
Drop impact & spreading
During my PhD I developed the first computational framework in [Sprittles & Shikhmurzaev 2013], based on the finite element method, which incorporated the IFM and thus allowed us to compare its predictions to a range of flows. In fact, to get to this stage a finite element framework for dynamic wetting had to be robustly developed, as outlined in [Sprittles & Shikhmurzaev, 2012]. The first process considered was microdrop impact and spreading on solid surfaces of varying wettability [Sprittles & Shikhmurzaev 2012a], see below.
Coalescence of liquid drops
The computational framework was adapted in order to study the coalescence of liquid drops using both the interface formation model and the conventional one, where in [Sprittles & Shikhmurzaev, 2012b] we could compared models to recent experimental measurements. This work was extended in [Sprittles & Shikhmurzaev, 2014] to account for the dynamics of an outer viscous fluid (i.e. air).