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DY: Fachverband Dynamik und Statistische Physik

DY 16: Convection

DY 16.1: Vortrag

Montag, 16. März 2020, 15:30–15:45, ZEU 147

Resolved energy budget of superstructures in Rayleigh-Bénard convection — •Gerrit Green^1,2, Dimitar G. Vlaykov^1,3, Juan Pedro Mellado⁴, and Michael Wilczek¹ — ¹Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany — ²Faculty of Physics, University of Göttingen, Göttingen, Germany — ³Astrophysics Group, University of Exeter, Exeter, UK — ⁴Department of Physics, Universitat Politècnica de Catalunya, Barcelona, Spain

Coherent large-scale flow patterns in the presence of turbulent small-scale fluctuations are a ubiquitous phenomenon in natural flows. Currently, the interaction of these so-called turbulent superstructures with small-scale fluctuations is not understood in detail. In order to clarify this interaction, we study superstructures by means of direct numerical simulations in Rayleigh-Bénard convection. This idealized model system shows a complex coexistence of turbulent fluctuations and superstructures. Here, we employ a filtering approach to separate the superstructures from the small-scale fluctuations. We study the resolved energy budget at the scale of the superstructures and characterize the different contributions to the budget, such as the energy input by buoyancy, the direct dissipation, and the energy transfer between scales. We find that the energy transfer primarily acts as an energy sink but exhibits a complex structure in the boundary layer. Our detailed analysis of the energy budget sheds light on the interaction between superstructures and small-scale fluctuations and may help to guide the development of reduced-order models.