Regensburg 2019 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 5: Convection
DY 5.4: Talk
Monday, April 1, 2019, 11:00–11:15, H3
Resolved energy budget of superstructures in Rayleigh-Bénard convection — •Gerrit Green1,2, Dimitar Vlaykov1,3, Juan-Pedro Mellado4, and Michael Wilczek1 — 1Max-Planck-Institute for Dynamics and Self-Organization, Göttingen, Germany — 2Faculty of Physics, University of Göttingen, Germany — 3University of Exeter, Exeter, England — 4Max-Planck-Institute for Meteorology, Hamburg, Germany
The dynamics of turbulent Rayleigh-Bénard convection exhibits a complex interaction between coherent large-scale flow patterns, so-called superstructures, and small-scale fluctuations. In this contribution we employ direct numerical simulations to investigate the interaction between scales and clarify the impact of turbulence on large-scale patterns. A filtering approach is used to separate the superstructures and turbulent fluctuations. It complements spectral analysis techniques by retaining physical space information. This allows us to study the energy budget at the scale of superstructures and to characterize the different contributions, such as the power input due to buoyancy, the direct dissipation and the energy transfer between scales. We find that the energy transfer in the bulk differs significantly from the one close to the walls. In the bulk, most of the energy input in the superstructures is balanced by the energy transfer between scales, which acts primarily as a dissipation for the large scales. Close to the wall, there is a layer in which the energy transfer is up-scale, driving the superstructures. Our investigations therefore provide insights which will help to derive an effective description of turbulent superstructures.