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Evangelia Antonopoulou

Postdoctoral Researcher
Oxford University
PhD project title
Challenges for Inkjet Technology: Dynamic Surface Tension


The first four years of my academic study were at the University of the Aegean, in Greece reading for a BSc in Mathematics that was completed in 2015. During that period, I took modules in subjects ranging from Analysis and Group Theory to Numerical Analysis and Scientific Computation. In my third year of study, I tackled a research problem of certain engineering significance in Fluid Dynamics. There, I studied steady, isothermal, Poiseuille flows of weakly compressible Newtonian fluids, under the assumption that both the mass density and the shear viscosity vary linearly with pressure. My BSc's dissertation was on Ergodic Theory. In addition, during my last year, I delivered small seminar talks in Fourier Analysis. I graduated with distinction from Heriot-Watt University, in Edinburgh in 2016 with an MSc in Mathematics. My MSc's dissertation dealt with Finite Element Approximation of Steady Flows of Non-Newtonian Fluids. I derived results concerning the numerical approximation of the weak solutions of the generalised Navier-Stokes system with shear rate dependent viscosity in the power-law model in the stationary settings.

Why I chose the CDT in Fluid Dynamics

The area helps me first to develop a solid background in Fluid Dynamics developing theoretical, computational and experimental techniques that I have not seen in my previous years of study. The CDT offers experience in applications valuable to both academia and industry and crucial for research and future professional career development. Finally, the interdisciplinary nature of the programme provides one with the opportunity to examine Fluid Dynamics within a vast range of adjacent topics and other interrelated areas.

Research Interests

The focus of my PhD project is the effect of dynamic surface tension and in particular the role of key active components, such as surfactants, and their effect on drop formation in the jetting process. The rapid expansion of the free surface during jetting means that local areas of surface will be depleted of surfactants leading to surface tension gradients. In this project we will develop a fluid dynamics model that incorporates these effects. The mathematical model is formulated using finite element methods and discretisation (FEM) which are then implemented numerically with FORTRAN 70. Numerical results have been validated against physical experiments which were conducted using facilities across the University of Leeds, Ricoh UK and the Physics of Fluids group, University of Twente, the Netherlands. For the first part of the project, the formation and evolution of micron-sized droplets of a Newtonian liquid generated on demand in an industrial inkjet printhead were studied experimentally and simulated numerically with the results of this work being accepted for publication in Physical Review Fluids. During the first year of CDT programme, I worked on a interdisciplinary MSc team project, which considers the settling behaviour of colloidal suspensions. This kind of behaviour can lead to phase separation of the system. We proposed an improved model to describe such systems with this kind of behaviour while we investigated the problem with highly controlled laboratory experiments. Consumer products such as e.g. Lenor and Downy, usually use this problem and hence many applications of this model can be seen in this area. During this project, I visited the P&G's European Technical Centre, the Brussels Innovation Centre in order to conduct many experiments. The model results were succesfully validated against these highly controlled experiments, with the work published in Physics of Fluids.

Selected Oral Presentations

  • “Effect of surfactants on jet break-up and drop formation in inkjet printing”, 72nd Annual Meeting of the American Physical Society’s Division of Fluid Dynamics, Seattle, Washington, USA (November 2019)
  • “Surfactants and jetting behaviour in inkjet printing”, Droplets 2019, Durham University, Durham, UK (September 2019)
  • “Jetting behaviour in the presence of surfactants in inkjet printing”, UK Fluids Conference 2019, DAMTP and Churchill College, University of Cambridge, UK (August 2019)
  • “Drop-on-demand inkjet printing of surfactant solution”, 9th International Meeting of Hellenic Society of Rheology, Samos, Greece (June 2019)
  • “Jetability of Inkjet Fluids”, 3rd UK Fluids Network Drop Dynamics SIG Meeting, Wadham College, University of Oxford, UK (September 2018)
  • “Finite Element Approximation of Stationary Electrorheological Fluids”, 16th Panhellenic Conference in Mathematical Analysis, University of the Aegean, Samos, Greece (June 2018)

Selected Poster Presentations

  • “Surfactant transport in inkjet printing“, Fundamental Fluid Dynamics Challenges in Inkjet Printing, Lorentz Centre, Leiden, The Netherlands (July 2019)
  • “Jetability of Inkjet Fluids”, UK Fluids Conference 2018, University of Manchester, UK (September 2018)
  • “Jetability of Inkjet Fluids”, EPSRC Centres for Doctoral Training Poster Event, University of Leeds, UK (May 2018)
  • “Jetability of Inkjet Fluids”, 2nd UK Fluids Network Drop Dynamics SIG Meeting 2, Wadham College, University of Oxford, UK (December 2017)
  • “Physical Separation and Settling Dynamics of Colloidal Systems”, UK Fluids Conference 2017, University of Leeds, UK (September 2017)
  • “Physical Separation of Colloidal Systems”, 8th International Meeting of The Hellenic Society of Rheology,  Hellenic Society of Rheology, Limassol, Cyprus (July 2017)
  • “Collapse of Colloidal Gels”, EPSRC Centres for Doctoral Training Poster Event, University of Leeds, UK (May 2017)

Selected Conference/ Workshop Attendance

  • Mathematics of Biology and Medicine Conference, University of Leeds, Leeds, UK (September 2019)
  • Graduate course in Advanced Perturbation methods, University of Leeds, Leeds, UK (February 2019)
  • Workshop on Droplet Coalescence, Durham University, UK (October 2017)
  • A Special Rheology Symposium in honour of Professor Roger I. Tanner on the Occasion of his 82nd Birthday, Samos, Greece (July 2015)

Research Visits

  • Physics of Fluids group, University of Twente, Twente, the Netherlands (Janurary-February 2020)
  • Ricoh UK Products Limited Inkjet Lab, Telford, UK
  • Procter & Gamble (P&G) Brussels Innovation Center, Brussels, Belgium (15-18 May 2017). Visiting: Vincenzo Guida (stability team)