Background
In piezo-acoustic ink-jet print heads, a voltage pulse, applied to the piezoelectric element, induces a deformation of the print head channel creating a pressure wave in the ink, ultimately responsible for the ejection of ink droplets out of the nozzle [1]. Given the extreme accuracy achieved by modern inkjet printers, technological advancement requires a thorough physical understanding of the droplet generation mechanisms and of the subsequent droplet formation process. This project will investigate key physical aspects beyond the formation of inkjet droplets and the influence of physical effects that may interfere with this process [2]. The project will be conducted in close collaboration with Canon Production Printing Netherlands B.V. and in the framework of a larger network of PhD students investigating -with different techniques- several aspects at the basis of ink-jet printing technologies. 

Project description
The selected candidate will perform numerical and theoretical research in order to investigate the fundamental physics beyond the dynamics of droplets formation in ink-jet print-heads. He/she will employ, extend and optimize existing numerical codes in order to perform high-fidelity, fully-3d numerical simulations of droplet jetting, will develop new codes to analyse the data produced, will develop novel, or improve upon existing, theoretical model also on the basis of the numerical investigations. The numerical methods that will be employed will include fully parallelized multiphase Lattice Boltzmann codes, developed in our group [3], as well as open-source codes based on volume of fluid method, like e.g. Gerris or Basilisk. The candidate will investigate full 3d effects, like the breaking of axial-symmetry during the jetting process cause by bubbles entrained in the nozzle. The candidate is expected to be familiar with theoretical methods for the description of multiphase, multicomponent fluids, in particular vapor bubbles, and their numerical implementation in the Lattice Boltzmann method. The candidate is expected to closely interact with Canon Production Printing Netherlands B.V., as well as with other PhD students performing theoretical/experimental studies.

References:

[1] Wijshoff, H. (2010). The dynamics of the piezo inkjet printhead operation. Physics Reports, 491(4), 77-177. doi.org/10.1063/1.4990082

[2] Detlef Lohse (2022). Fundamental Fluid Dynamics Challenges in Inkjet Printing. Annual Review of Fluid Mechanics 54(1), 349-382. 10.1146/annurev-fluid-022321-114001

[3] Karun P.N. Datadien, Gianluca Di Staso, Herman M.A. Wijshoff, Federico Toschi (2021). A quantitative comparison of physical accuracy and numerical stability of Lattice Boltzmann color gradient and pseudopotential multicomponent models for microfluidic applications. https://arxiv.org/pdf/2110.05197.pdf

Location

These projects will be carried out within the Fluids and Flows group at the Department of Applied Physics (https://www.tue.nl/en/research/research-groups/fluids-and-flows/) of Eindhoven University of Technology. The PhD candidates will be supervised by prof. F. Toschi.

Requirements

We are looking for enthusiastic PhD-students with an excellent background in fluid dynamics and computational physics. You have an MSc in (applied) physics or mechanical engineering. Knowledge of multiphase fluid dynamics and parallel programming are an asset. Close affinity with computational physics is a must. As an ideal candidate you should be able to work in a team. You also have good written and oral communication skills in English.

We offer:

• An exciting job in the active group Fluids and Flows, with strong national and international collaborations.
• A full-time appointment for four years at Eindhoven University of Technology http://www.tue.nl/en/.
• Gross monthly salary from €2443 (first year) to €3122 (fourth year) in line with the Collective Agreement for Dutch Universities.
• Benefits in accordance with the Collective Labor Agreement for Dutch Universities.
• Additionally, an annual holiday allowance of 8% of the yearly salary, plus a year-end allowance of 8.3% of the annual salary.
• A broad package of fringe benefits, including an excellent technical infrastructure, moving expenses, and savings schemes.
• To develop your teaching skills, you will spend 10% of your employment on teaching tasks.
• To support you during your PhD and to prepare you for the rest of your career, you will make a Training and Supervision plan and you will have free access to a personal development program for PhD students (PROOF program).
• Should you come from abroad and comply with certain conditions, you can make use of the so-called '30% facility', which permits you not to pay tax on 30% of your salary.
• Family-friendly initiatives are are in place, such as an international spouse program, and excellent on-campus children day care and sports facilities.