The Spatial Structure of Turbulent Rayleigh-Benard Convection

The circulation cells visualized in the present study are a manifestation, in the fully turbulent regime, of the cellular structures commonly observed at low Rayleigh numbers. The circulation cells are proposed as a physical description (not an explanation) of the phenomenon referred to in the literature as the wind of turbulence. They were found to contain approximately 40% of the total kinetic energy, and this fraction was found to be approximately independent of the Rayleigh number. This leads to the conclusion that the wind of turbulence (U) scales with the velocity fluctuations (ufluct), U ∼ u fluct. The visualizations indicate that the large-scale circulation engulfs the small-scale structures and advect them across the layer. The engulfment of small-scale buoyant elements may be the mechanism by which the large-scale circulation obtains the buoyancy required to maintain its kinetic energy.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Theoretical and Applied Mechanics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Fernandes, Richard Lawrence Joseph

Contributors dc:contributor

• Adrian, Ronald J.

• Physics, Fluid and Plasma

Language dc:language

eng

Identifier

(MiAaPQ)AAI9996631

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/87776