Practical trainings, student assistants and theses

A multiphase jet is the ejection of a fluid, in which different particles, bubbles and droplets are finely dispersed, from a small orifice. Examples of such systems are the ash clouds of volcanos, the liquid droplets from a spray can or the injection of bubbles in an underwater ramjet engine.

In our numerical and experimental studies of the bubbly jet [1], we encountered an interesting phenomenon that bubbles are pushed out of the jet centre into a thin layer at the jet boundary. This effect may be used to improve mass transfer or bubble-particle collisions in applications such as chemical reactors and mineral flotation. The task of this student work is to perform an experimental parameter study with an optical Doppler probe [2], measuring profiles of the bubble speed, size and volume fraction for different water and air flow rates. The results will elucidate the interaction of liquid flow with bubbles and how the bubble “hole” in the jet centre is affected by the process parameters.

The thesis subject includes…

• conducting and protocolling experiments with advanced optical measurement equipment
• evaluation and interpretation of the measurement data

[1] Zürner et al., Min. Eng. 211 (2024), DOI: https://doi.org/10.1016/j.mineng.2024.108699
[2] Lefebvre et al., Chem. Eng. Sci. 250 (2022), DOI: https://doi.org/10.1016/j.ces.2021.117359

• Field of study: Process engineering, mechanical engineering, fluid mechanics, physics or similar orientation
• Advantageous are experiences in laboratory work, evaluation of measurement data (e.g. programming skills) and optical measurement methods
• Ability for practical, accurate and independent work
• Good language skills in English and/or German

• Place of work: HZDR
• Start: from March 2026
• Duration: min. 4 months
• Remuneration according to HZDR internal regulations

X-ray computed tomography (XCT) is a 3D imaging technique used for the visualization of internal structures of the sample. High energy X-ray beam is used to penetrate the sample and the different attenuation coefficients of each component (phase) within the sample make it possible to quantify and visualize the 3D distribution of these components.
In our laboratory we analyze minerals and metals in primary and secondary raw materials.
Experimental/laboratory/software work
Your tasks:

• Sample preparation of particulate samples for 3D characterization
• Scan of samples at CT CoreTOM
• Reconstruction of CT data
• Processing the CT data using software Avizo, Dragonfly, ImageJ

Bachelor/Master student (f/m/d) in the field of in earth sciences, physics, chemistry, material sciences, engineering with interest in image processing and the use of sophisticated software

Maximum weekly working hours: 19 hours. Initially limited until 30 June 2026, place of work: Freiberg (HIF)

At Helmholtz-Zentrum Dresden-Rossendorf (HZDR), over 1,500 employees from more than 70 nations are conducting cutting-edge research in the fields of ENERGY, HEALTH, and MATERIALS to address the major challenges facing society today.
The Center for Advanced Systems Understanding (CASUS), founded in Görlitz in 2019, is a German-Polish interdisciplinary research center focusing on data-intensive digital systems.
CASUS offers student internships in a wide range of scientific fields. You are welcome to apply and join CASUS if you are interested in gaining knowledge in the following research areas:

• Theoretical Chemistry
• Earth System Science
• Systems Biology
• Digital Health
• Computational Radiation Physics
• Theory of complex systems
• Dynamics of Complex Living Systems
• Machine Learning for Infection and Disease

• Student in computer science, physics, chemistry, or related fields
• Student already enrolled at the university in Germany, Poland or Czech Republic (close exchange and attendance in the office preferable and combined with the moblie working from Germany combinable)
• Eager to learn new skills
• Strong motivation to work in a collaborative environment
• Preliminary experience in code development is an advantage
• Excellent communication skills in English and/or German or Polish

• A vibrant research community in an open, diverse and international work environment
• Scientific excellence and extensive professional networking opportunities
• A wide range of qualification opportunities
• We support a good work-life balance with the possibility of part-time employment, mobile working and flexible working hours
• Either an immediate start or a start in 2024 is possible