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Description
The project aims to explore the properties of turbulent von K´arm´an swirling flow (VK flow). VK flow can be briefly described as flow within a vessel closed from both sides with impellers spinning in the opposite directions. The flow exhibits a characteristic mean pattern consisting of two, samesize, toroidal cells inside which fluid continually circulates. On top of that, fluid spins around the vessel axis, and the rotation rate changes gradually along the axis to match angular velocities of the impellers. As a result of this composition, the flow velocity vanishes close to the vessel centre, forming a stagnant region.
VK flow is one of the canonical flows in turbulence research. It has been a subject of multiple theoretical, experimental, and numerical works, spanning over a wide range of topics. There are a few features which make this flow configuration particularly appealing for researchers, e.g. highly energetic turbulent motion can be created in a relatively compact experimental apparatus. It is hardly arguable that VK flow is important for turbulence research, and the better it is understood, the better it can serve for all kinds
of turbulence-related research.
The particular aspect of VK flow that the project aims to investigate is a recently observed feature of the flow field, which appears in the vicinity of its stagnant region. The feature is the strongest close to the vessel centre, where it accounts for more than half of the turbulence energy, and weakens progressively away from the centre. The project goal is to address the following four research questions about the described flow feature: (i) is this phenomenon reproducible in different facilities, (ii) how sensitive is it to the history of the flow, (iii) how sensitive is it to the geometry of the vessel, (iv) can it be controlled via different stirring strategies. By answering these, the project is meant to broaden our understanding of VK flows.