NanoLPC: Engineering Light-induced Phase Change for emerging Nano-scale processes

27.02.2025, Wissenschaftliches Personal

Phase change and industrial relevance

Phase change such as vaporization, condensation, melting, and solidification is a first-order phase transition involving latent heat, which is an old topic but has become increasingly important for many emerging applications. In additive metal manufacturing, melting and solidification are the basics of the printing process. Still, laser-induced vaporization and the formation of keyhole pores, i.e., porosity defects, are currently a major limiting factor for metal printing. In nanomedicine, various nanoparticles are used for controlled drug delivery and therapies, and laser-excited nanobubble-inducing shockwave is a powerful tool for ablating vitreous opacities in vivo. In solar energy utilization, direct steam generation/vapor production from bulk or surface fluid surface is a promising technology for enhancing solar energy efficiency in the post-fossil fuel era and improving clean water production.

Light-induced phase change

The fundamental physics governing these different processes is the light-induced phase change (LPC) due to the strong non-linear interaction of light and absorbing materials, leading to different phase change phenomena across different scales. These various processes follow some common consequent paths, i.e., light-absorber interaction (LAI) leads to temperature rise of the absorber, which induces localized phase change, and phase change interaction with the surrounding renders different effects, either preferred or unwanted.

Phase change has been a long research topic in thermodynamics and heat transfer. Considering the fundamental process of phase change, which ranges from nucleation to strong interfacial heat and mass flow coupling, it is still a forefront research area with many challenges ahead because of its multiscale nature. LPC adds further complexities by introducing the multiphysics nature due to the strong LAIs.

Due to such multiscale multi-physics nature, understanding and manufacturing LPC for designed processes is highly challenging, which ranges from strong non-linear LAIs, size-dependent properties prediction, mis-linkage between what occurs at the nanoscale and bulk scale, and transient NB dynamics associated with shockwave penetration, as well as the difficulties of performing nanoscale experiments to obtain reliable measurement, especially under strong influence of phase change. For current engineering applications, only some empirical correlations / simplified equations are used to describe LPC in different sectors. There is a strong need to advance our understanding of the LPC process and develop reliable physics-informed tools to predict and reverse engineering the LPC process for emerging applications.

Aim and Objective

In this project, we define LPC as the unifying theme for different non-related emerging applications. We will conduct a systematic study of light-induced phase change phenomena from multiscale and multiphysics aspects. In particular, we will

• Unify the LPC study from three fundamental processes, i.e., light absorber interaction, light-induced phase change, and phase changed-induced interactions.
• Establish a unique physics-informed multiscale simulation platform, validated by multiscale phase change experiments, to advance the fundamental understanding of LPC.
• Develop LPC applications in different emerging industries, from additive manufacturing and nanomedicine to solar energy.

Major Work

We will develop systematic approaches to provide a fundamental understanding of NanoLPC from multiscale experimentation and simulation aspects, not only to enhance the knowledge of LPC throughout different scales but also to support a range of emerging applications:

• Establish a light-induced multi-physics and multiscale phase change simulation platform, which allows us to capture LAI and couple molecular information into macroscopic phase change simulation.
• Establish a multiscale LPC experimental system, which allows probing light-induced phase change mechanism and provides valuable validation data for the multiscale modeling above.
• Develop NanoLPC application in solar energy by exploring fundamentally the controversy regarding the abnormal evaporation rate and simulate/ predict vapor production rate to guide the design of an optimized interfacial evaporator.
• Develop NanoLPC application in nanomedicine by establishing a unique multi-model experimental system together with functionalized nanomaterials to examine the nanobubble phenomenon, supported by multiscale numerical studies.
• Develop NanoLPC application in additive manufacturing by developing a multiscale simulation tool for keyhole dynamics and pore formation prediction suitable for PBF applications.

Expected outcome

Tackling the fundamental challenge of the formation and control of LPC and developing a physics-informed platform will not only advance LPC understanding in the domain of Thermodynamics and Heat Transfer but also transfer the developed expertise into emerging applications. Many breakthroughs beyond state-of-the-art work are expected, such as i) the establishment of a unique multi-physics and multiscale LPC simulation platform, ii) the revelation of LPC mechanisms by multiscale experiments with localized temperature and nanobubble dynamics measurement, and iii) the reverse engineering of LPC to maximize solar vapor production, inhibit key-hole pore formation and control nanobubble shockwave effects.

Talent calling

The project also opens several job opportunities for ambitious researchers (both postdoc working and PhD students) to join us and work at the forefront of this exciting project from November 2024.

We are looking for outstanding /ambitious candidates with strong expertise/background in

• Multiscale coupling and simulation
• Nanoscale heat transfer experimentation
• Light-matter interactions
• Nucleation and phase change physics
• Functional nanomaterials and interface
• Heat-related nanomedicine
• Metal printing and additive manufacturing
• Solar interfacial reactor

What we offer

Payment according to TV-L West E13 in full-time (40 hours a week).

TUM has been pursuing the strategic goal of substantially increasing the diversity of its staff. As an equal opportunity and affirmative action employer, TUM explicitly encourages nominations of and applications from women and all others who would bring additional diversity dimensions to the university’s research and teaching strategies. Preference will be given to disabled candidates with equal qualifications. International candidates are highly encouraged to apply.

Application

Professor Wen is looking forward to receiving your informative documents. Please send your application by email to d.wen@tum.de in a single PDF file (incl. an introductory letter, CV, qualification documents, list of publications, and any references you might have).

Do not hesitate to contact the office for any administrative questions (+49.89.289-16217) office.tfd@ed.tum.de.

If you apply in writing, please submit only copies of official documents, as we cannot return your materials after completing the application process.

For more detailed information, please visit our Homepage: https://www.epc.ed.tum.de/td/stellenangebote/ 

Kontakt: Ms. B. Blume / Ms. B. Müller - office.tfd@ed.tum.de