On Friday, 19th June 2020, Sina Ackermann successfully defended her doctoral thesis entitled „A multi-scale approach for drop/porous-medium interaction" with the best result "summa cum laude". Sina is a doctoral student at the Department of Hydromechanics and Modelling of Hydrosystems. She wrote her thesis within the International Research Training Group „Droplet Interaction Technologies" (GRK 2160/1: Dropit)" which is financed by the Deutsche Forschungsgemeinschaft . Due to the present Corona-restrictions, only the examination committee could attend the talk which was streamed via youtube for the general public.
Drop formation at the interface of a gaseous free-flow and a two-phase flow in a hydrophobic porous medium can be observed in many technical applications. Examples are the water management of fuel cells, thermal insulation of building exteriors or turbine heat exchange processes. The interfacial drops are typically small compared to the spatial scales in such coupled systems. However, they have a strong influence on the exchange of mass, momentum and energy between the two flow compartments. In this work, we develop a multi-scale coupling concept to model the influence of droplet-related pore-scale processes on the macroscopic flow behavior in the adjacent flow regimes. In our three-domain approach, drop formation, growth, detachment and film flow along the interface are taken into account in a lower-dimensional interface domain. Instead of resolving the drops individually, we apply a simple upscaling procedure. We present numerical results for a single-drop setting, as well as more complex test cases for different parameter combinations. The behavior of the drops as well as their influence on the adjacent flow regimes are shown and discussed.
- First Supervisor: Prof. Dr.-Ing. Rainer Helmig (Department of Hydromechanics and Modelling of Hydrosystems)
- Secondary Supervisors: Prof. Dr.-Ing. Bernhard Weigand (IInstitute of Aerospace Thermodynamics), Prof. Dr.-Ing. Maurizio Santini (Universita degli studi di Bergamo, Dipartimento di Ingegneria e Scienze Applicate)
- Chairman: Prof. Dr. rer. nat. Dr.-Ing. András Bardossy (Department of Hydrology and Geohydrology)