Related Experiment Video
Updated: May 24, 2026

Visually Based Characterization of the Incipient Particle Motion in Regular Substrates: From Laminar to Turbulent Conditions
Published on: February 22, 2018
Plume fragmentation by bulk interactions in turbulent Rayleigh-Bénard convection
Johannes Bosbach1, Stephan Weiss, Guenter Ahlers
1Department of Physics, University of California, Santa Barbara, California 93106, USA.
Abstract:
Using compressed gases with Prandtl numbers near 0.7, we obtained flow visualizations of turbulent Rayleigh-Bénard convection in a cylindrical sample with an aspect ratio Γ≡D/L≅10 (D is the diameter and L the height) by the shadowgraph method. Focusing on the plumes under the top plate, we found that their length had a log-normal distribution, suggesting a fragmentation process. Fragmentation events could be visually identified in the images and involved plume interactions with bulk fluctuations or upwelling domain walls. We found the mean spacing between plumes to vary with the Rayleigh number in proportion to the volume-averaged Kolmogorov length of the turbulent bulk fluctuations, providing further evidence for plume-bulk interactions.
Related Concept Videos
Boundary Layer Characteristics
Steady, Laminar Flow Between Parallel Plates
Poiseuille's Law and Reynolds Number
Turbulent Flow
Laminar and Turbulent Flow
Couette Flow

