The team ran an experimental campaign at the Institute of Multiphase Flows, Hamburg University of Technology, commissioning a bubble column rig for optical measurements.
What was measured
The campaign centred on a rectangular bubble column and on two independent ways of reading its gas holdup. The first is the classical one: the expansion of the bed as the gas flow rate is raised, which gives the global holdup and, through the shape of that curve, the flow regime transition points. The second is magnetic resonance imaging, which the Institute of Multiphase Flows applies to multi-phase systems and which resolves the holdup spatially instead of averaging it over the whole column.
Running the two together is what makes the campaign useful to AURIGA. The bed-expansion curve tells where a transition happens; the MRI field tells what the flow actually looks like on either side of it — whether the change is a loss of the mono-dispersed structure, the onset of a coalescence-driven regime or the establishment of a large-scale circulation. That is precisely the local-to-global link that the theoretical work package needs in order to model the transitions rather than correlate them.
The results were presented at CHISA 2026 in Prague as a joint contribution with the Hamburg University of Technology.