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Experimental evidence for jump rope vortices in turbulent convective superstructures

Year: 2026
Type: article
Abstract: We investigate turbulent Rayleigh-Bénard convection (RBC) in a convection cell with square cross section and aspect ratio Γ = width / height = 25 filled with the liquid metal alloy GaInSn at Prandtl number P r ≈ 0.03 . A dense array of thermocouples and ultrasonic Doppler velocimetry is employed to measure the temperature distributions at the top of the convection cell and horizontal velocity profiles, respectively, in the Rayleigh number range 3.27 × 10 4 ≲ Ra ≲ 2.17 × 10 5 . Conspicuous thermal structures manifest themselves in the two-dimensional temperature fields and closely resemble the turbulent superstructures predicted in numerical simulations. The velocity data reveal flow features that indicate the presence of “jump rope vortices” (JRV). This can be seen in characteristic oscillations that permeate the entire 3D flow structure. The measured frequencies, f 0 correspond very well with the empirical scaling f 0 ∝ Ra 0.419 . The results thus provide experimental evidence that the jump-rope vortex, which has previously been identified as the striking dynamical feature of large-scale convection (LSC) in geometries with moderate aspect ratios ( 1.4 ≤ Γ ≤ 5 ), also persists as a robust, three-dimensional mode embedded within turbulent convective superstructures at very large aspect ratios.
DOI: 10.1103/653m-gc8d
Language: English
Open Access status: hybrid
OpenAlex ID: W7161113362
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Cites: 41
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Related to: 10