Dresden 2017 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 16: Focus: Fundamental aspects of turbulent convection

DY 16.6: Vortrag

Dienstag, 21. März 2017, 11:00–11:15, ZEU 118

Turbulent heat transport in low-Pr number fluids — •Lukas Zwirner and Olga Shishkina — MPI Dynamik und Selbstorganisation, Göttingen

Turbulent convective heat transport is ubiquitous in nature. Rayleigh-Benard convection (RBC), where a fluid layer is confined between a lower heated plate and an upper cooled plate, is a classical model system to investigate turbulent convective heat transport. With any tilt of a RBC cell against gravity, the global flow structure in the convection cell changes, which leads to a change of the heat transport.

The purpose of the present work is to investigate by means of direct numerical simulations how heat and momentum transport, represented, respectively, by the Nusselt number and Reynolds number, depend on the main input parameters of the convective system. Those are the Rayleigh number Ra, Prandtl number Pr and the inclination angle of the convection cell. Thereby, the focus is set on convective flows in cylindrical containers of a small diameter-to-height aspect ratio Γ, Γ=1/5, and Pr ≤ 1. For each studied combination of Ra, Pr and Γ, an optimal inclination angle of the convection cell, providing maximal heat flux is determined. Furthermore, for the particular case of RBC (with zero inclination angle of the cell), different possible (e.g. single- or double-roll) states of the large scale circulation are studied in detail, including their influence on global heat transport in the system.