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DY: Fachverband Dynamik und Statistische Physik

DY 4: Fluid Physics and Turbulence

DY 4.1: Invited Talk

Monday, March 18, 2024, 09:30–10:00, BH-N 128

Towards the ultimate regime in Rayleigh-Benard turbulence — •Olga Shishkina — Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany

Rayleigh-Benard convection -- a fluid flow in a container heated from below and cooled from above -- is one of the paradigmatic systems in fluid dynamics. Here the key response of the system is the heat transport (Nusselt number Nu) and the key question is: how does Nu depend on the thermal driving strength (Rayleigh number Ra), in particular for extremely large Ra -- the case which is relevant in many astrophysical and geophysical systems? We will start with a brief digression into the history of the theory of heat transport scaling relations for large Ra, and in particular for the so-called ultimate regime, where the scaling laws do not change anymore with the further growing Ra. We will discuss the assumptions and outcomes of the various scaling models as well as the factors that influence the transition to the ultimate regime, including the container shape, wall roughness, specific thermal boundary conditions, and possible non-Oberbeck--Boussinesq effects, as well as the multiple-state nature of turbulent thermal convection.

Keywords: turbulence; convection; Rayleigh-Benard convection; heat transport; theory