From a scientific perspective, contact line motion remains a challenging subject for both theoretical, experimental and numerical fluid mechanics due to the occurrence of a shear stress singularity at the three-phase contact line. In technological applications such as immersion lithography, it is desirable to displace liquid across a partially wettable but heterogeneous (wafer) surface as quickly as possible and without leaving any residue. In this project you will investigate the interplay between capillary and inertial aspects of contact line motion and its interaction with non-flat surface topography and variable surface composition. You will specifically consider the critical substrate speed - corresponding to the transition towards droplet shedding or the entrainment of thin films on the surface - as a function of



the geometrical and compositional surface parameters. You will also study the dynamics of splashing, which occurs on topographically patterned surfaces, when an array of high-speed gas-jets is used to displace and control the receding side of the liquid meniscus.

This project consists of a combination of experiments and numerical simulations. The experiments will involve high-speed visualization of contact-line dynamics on suitably prepared surfaces. You will study surface heterogeneities both regarding composition and topography and systematically vary the dimensions, shapes and amplitudes of the patterns. The numerical simulations will be based on open-source VOF solvers (such as Basilisk and Gerris), which can deal with the relevant density and viscosity contrast between liquid and air and inertial free-surface flow phenomena in a computationally highly efficient fashion.

You will become a member of the group Fluids & Flows of the Department of Applied Physics and contribute to our research line of Micro- and Nanofluidics. This project is part of a larger research program that involves close collaboration with the University of Twente and the research division of ASML. Moreover, it is embedded in the J.M.Burgerscentrum - the Dutch National Research School on Fluid Mechanics. It offers the unique opportunity for you to do high-level fundamental research with clear application-inspired and technology-relevant aspects. Your results will help improve immersion lithography, which is a fabrication technology for semiconductor devices that are at the heart of all modern technology (e.g. computers, smart phones, electrical cars, …).

Besides research you will also contribute to education within our group and the Department of Applied Physics. You will guide and supervise BSc and MSc students in their research projects. Other assistance in education, e.g. in BSc-level courses, is usually limited to around 5% of your contract time. Note that if you are specifically interested in teaching and education, there is the option for a 1-year extension of your PhD studentship. Your teaching and education tasks will then amount to a time equivalent of more than a full contract year during your PhD project. Please express your interest to the vacancy holder/supervisor in charge.

For the experimental position, we are looking for an enthusiastic PhD-student with an excellent background in fluid dynamics. Typically, you have an MSc degree in (applied) physics, mechanical or chemical engineering. Prior experience with experiment design, instrument control, data acquisition and image analysis are assets.

For the numerical position, we are looking for an enthusiastic PhD-student with an excellent background in fluid dynamics and computational physics. You have an MSc degree in (applied) physics or mechanical engineering. Knowledge of multiphase fluid dynamics, computational fluid dynamics codes and parallel programming are an asset. Close affinity with computational physics is a must.

Both candidates should be able to work in a team and have good written and oral communication skills in English.

A meaningful job in a dynamic and ambitious university, in an interdisciplinary setting and within an international network. You will work on a beautiful, green campus within walking distance of the central train station. In addition, we offer you:

• Full-time employment for four years, with an intermediate evaluation (go/no-go) after nine months. You will spend 10% of your employment on teaching tasks.
• Salary and benefits (such as a pension scheme, paid pregnancy and maternity leave, partially paid parental leave) in accordance with the Collective Labour Agreement for Dutch Universities, scale 27.
• A year-end bonus of 8.3% and annual vacation pay of 8%.
• High-quality training programs and other support to grow into a self-aware, autonomous scientific researcher. At TU/e we challenge you to take charge of your own learning process.
• An excellent technical infrastructure, on-campus children's day care and sports facilities.
• An allowance for commuting, working from home and internet costs.
• A Staff Immigration Team and a tax compensation scheme (the 30% facility) for international candidates.