Ultimate turbulence regime

Turbulence is everywhere: in the air around us as a consequence of our own body heat, in heated living rooms, in the atmosphere, in oceans, in the earth and in stars. For a long time researchers thought that turbulence was universal in nature but that is not the case. Even in a single system - for example the flow in a container with heated water at the bottom and cold water at the top – different turbulence regimes can develop. Now the question is: how do transitions take place and is it possible to switch between two turbulence regimes?

In this research scientists are trying to find answers to these questions by means of theoretical, numerical and experimental research. They are using two model systems: the flow in the aforementioned container with heated and cooled liquid and the flow between two identical rotating cylinders, which rotate in the same direction or in opposite directions. The ultimate objective is to make statements about the development of different turbulence regimes and the characteristics of these. This knowledge will contribute to a better understanding of flow behaviour at transitions in oceans, process technology, and in the atmosphere.

Programme leader professor Detlef Lohse (University of Twente): "The transition to the ultimate turbulence regime is particularly interesting. This is a transition in the boundary layer of the flow against the walls that eventually changes the flow in the entire container. If such a change occurs, one can no longer extrapolate small-scale experiments in the lab to large-scale convection in the atmosphere, oceans, or in stars. If we want to predict the turbulent heat transfer in large scale systems we have to understand the transition, and that is what we want to achieve in this programme".

The programme is a close collaboration between the research groups of Physics of Fluids in Twente (Lohse, Sun), the Vortex Dynamics group in Eindhoven (Van Heijst, Clercx, Toschi), the Hydrodynamics and Aerodynamics Group in Delft (Westerweel, Delfos, Elsinga) and the Applied Mathematics group in Twente (Geurts, Botchev), together with part-time professors Verzicco (University of Twente) and Eckhardt (Delft University of Technology).