Sascha Heitkam has been head of an Emmy Noether Young Investigator Group at Helmholtz-Zentrum Dresden Rossendorf (HZDR) and TU Dresden since 2020. Emmy Noether Junior Research Groups are directly funded by the German Research Foundation. They enable outstandingly qualified young researchers to lead a project group and qualify for a university professorship. Sascha Heitkam's junior research group is experimentally investigating the fluid mechanics of foams. In the interview, Sascha Heitkam tells us what he is researching and what drives him.
What are you currently working on?
Sascha Heitkam: Foams are opaque and very unstable. Therefore, most established measurement techniques of fluid mechanics are not applicable for foams. Accordingly, the dynamic behavior of foams is also poorly understood. And in industrial plants, techniques to analyze and optimally manage foams are missing.
Currently, we are developing and adapting innovative measurement techniques for foams in my group. In doing so, I can partly draw on in-house developments at the HZDR. However, I also cooperate with international partners to test alternative measurement techniques such as neutron radiography or positron emission tomography on foams.
On the one hand, we want to use these measurement techniques to better understand the fluid mechanics of foams. On the other hand, we want to develop commercially applicable sensors for industrial plants. In doing so, we are primarily targeting froth flotation. This is currently used for ore flotation. However, optimized flotation techniques could also make a significant contribution to recycling, e.g. of electronic components.
What is your personal motivation?
Sascha Heitkam: I am fascinated by the complex dynamics of foams. Everyone has had foam in their hands and you think you have a certain understanding or at least an intuition of how foam behaves. But if you delve deeper, you discover a complex interplay of mechanisms on very different time and length scales. The sorption of surfactant molecules at the interfaces interacts with the liquid distribution in the foam, which in turn influences the dynamics of neighboring bubbles, which then dictates the flow behavior. And the flow of the foam in turn influences the liquid distribution and thus the surfactant concentration in the foam.
Accordingly, foams are also a highly interdisciplinary topic, with researchers from chemistry, physics, mathematics and engineering puzzling together. Because of the many aspects involved, there is hardly any competition in our community. Instead, hypotheses or ideas are freely communicated and often worked on in cooperation. This is very motivating, especially for young researchers.
What kind of challenges are you facing in the near future?
Sascha Heitkam: We have made very good progress in developing measurement techniques. Now we will apply these techniques to better understand foam flows. For example, I want to see if there is such a thing as turbulence in foam flows. And if so, how small eddies behave that are only slightly larger than the bubbles. However, due to the complex dynamics of foams, it is very difficult to design such experiments and make them reproducible.
If you could make a wish for something for your research, what would you wish for?
Sascha Heitkam: I am still very interested in testing further measurement techniques on foams. In particular, spatially resolved measurements of water contents, velocities, mechanical stresses or pressures are relevant for my research. So if anyone has an exciting measurement technique and is interested in testing it on foam, I would be happy to come by with a mobile and well characterized foam flow.
Where do you see your discipline in 5-10 years?
Sascha Heitkam: An important goal for me is to link foam research more closely with industrial applications. The behavior of foams is very complex. Therefore, a sound understanding is necessary to successfully combat or optimize foams in industrial plants. While this understanding exists, many researchers are not very well connected with industry. Through better interaction, for example in projects with industry participation, academic knowledge needs to be better translated into industrial practice. For example, foamability, flow behavior, drainage, and foam decay are relatively well understood in an academic setting. This knowledge could also be used to better study complex industrial material systems. I personally would like to contribute here with innovative foam sensors.