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Investigation Of Turbulent Superstructures In Rayleigh-Benard Convection By Lagrangian Particle Tracking Of Fluorescent Microspheres

S. Weiss, D. Schanz, A. O. Erdogdu, A. Schröder, J. Bosbach

Department of Experimental Methods, Institute of Aerodynamics and Flow Technology,

German Aerospace Center (DLR), Göttingen, Germany

We present spatially and temporally resolved velocity measurements of turbulent Rayleigh-Bénard convection (RBC) in a fluid sample of square horizontal cross section with length L = 320 mm and height H = 20 mm, resulting in an aspect ratio of Γ = H/L = 16. The working fluid was water with a Prandtl number of Pr=7 and the Rayleigh-number was set to Ra = 1.1 × 10^6. We seeded the flow with fluorescent polyethylene microspheres that were photographed at a rate of 19 Hz by six cameras. From the images the particle position and their velocity was calculated via the "Shake-The-Box" (STB) Lagrangian particle tracking algorithm. With this approach, we could simultaneously track more than 300,000 particles and hence study the resulting turbulent structures in the Eulerian and Lagrangian frames.

20th Edition
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