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Boundary Layer Heat Transport in turbulent Rayleigh‐Bénard Convection in Air
Author(s) -
du Puits Ronald,
Resagk Christian,
Willert Christian
Publication year - 2014
Publication title -
pamm
Language(s) - English
Resource type - Journals
ISSN - 1617-7061
DOI - 10.1002/pamm.201410312
Subject(s) - laminar flow , flow visualization , turbulence , particle image velocimetry , mechanics , boundary layer , optics , rayleigh scattering , perpendicular , convection , plane (geometry) , flow (mathematics) , geometry , materials science , physics , mathematics
We study the convective heat transfer in a large‐scale Rayleigh‐Bénard (RB) experiment which is called the “Barrel of Ilmenau”. We present the results of flow visualization and Particle Image Velocimetry (PIV) measurements of the near wall flow field in a plane perpendicular to the surface of the heated bottom plate. The experiment was run in a smaller rectangular inset that was placed inside the larger barrel. The Rayleigh number amounts to Ra = 1.4 × 10 10 . The aspect ratios were Γ x = 1 in flow direction and Γ y = 0.26 perpendicular to the vertical flow plane. The measurements have been undertaken using a 2 W continuous wave Laser in combination with a light sheet optics and various cameras. Due to the slender geometry of the cell, the mean wind is confined in one direction where the Laser light sheet is aligned parallel. The flow was seeded with droplets of 1...2 µm size generated using an ordinary fog machine. Flow visualization as well as the PIV data clearly show the intermittent character of the boundary layer flow field that permanently switches between “laminar” and “turbulent” phases. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)