FOM PhD position: Turbulent Rayleigh-Bénard convection (numerics)Turbulent flow is omnipresent in nature and technology. In contrast to a decade-old paradigm, even highly turbulent flow is strongly influenced and determined by the boundaries. There is increasing evidence that there are different states of turbulent flow, with sharp transitions and bifurcations in between them. These observations make it very difficult to extrapolate the results from lab-scale experiments to industrial, geophysical, or even astrophysical flows. We want to examine experimentally, numerically, and theoretically whether there are indeed different states of turbulence, how they are triggered, and what the nature of the transitions between them is. We focus on turbulence in closed systems, namely on Rayleigh-Benard turbulence and Taylor-Couette turbulence. In these paradigmatic systems – thermally or shear driven, respectively – the interplay between boundary layers and bulk is of particular importance. We want to understand the transition towards the so-called ultimate turbulent state, which for extremely strong driving had recently been found in both of these systems and which had been interpreted as an indication of the breakdown of laminar-type boundary layers. To achieve our goals, we have to further advance the level of experimental measurements and numerical simulations on these two systems, to allow for one-to-one comparisons. In this particular part of the project the PhD student will perform numerical simulations with the finite difference code developed by Verzicco and coworkers: Further parallelization will be necessary to achieve the ultimate regime and to understand the physics therein. The postdoc will perform experiments in our turbulent Twente Taylor-Couette setups: PIV, drag measurements, surface manipulation.
Information and Applications
For more information and applications, please contact Prof. Dr. Detlef Lohse, Physics of Fluids, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.