On 23 November 2023, Philipp Grohn presented his dissertation entitled "Numerical investigation of the influence of liquid on particle dynamics in a fluidised bed rotor granulator" in a public university colloquium and defended it with distinction.

In his dissertation, Philipp Grohn investigated the particle dynamics in dense shear gas-particle flows in fluidised bed rotor granulators using numerical and experimental methods. These systems are frequently used for the production of pellets in processes such as spray granulation or agglomeration and coating in the pharmaceutical, chemical and food industries.

The influences of the liquid sprayed for coating on the particle interactions and bed dynamics were simulated using the discrete element method (DEM) coupled with computational fluid dynamics (CFD). To this end, the micro-processes of the impact of wetted particles were investigated experimentally. The new findings show a significant influence of the impact velocity on the geometry and length of the liquid bridge and thus on the interparticle forces. The new dynamic models for the maximum bridge length in particle-particle and particle-wall contact were developed to describe these influences. CFD-DEM parameter studies were used to describe the complex particle dynamics in rotor vortex layers and to clarify the important influences of the process parameters and fluid properties.

The work was assessed by the reviewers Prof Sergiy Antonyuk from the Chair of Particle Process Engineering at the University of Kaiserslautern-Landau (RPTU) and Prof Stefan Heinrich from the Institute of Solids Process Engineering and Particle Technology at the TU Hamburg.