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Communication Dans Un Congrès Année : 2022

Thermal plumes in turbulent Rayleigh-Bénard convection using Laser-Induced Fluorescence

Résumé

Thermal convection is a physical process present in many natural and industrial processes for which Rayleigh-Bénard convection is a paradigm. Lately the role of the thermal boundary layers on the global heat transfer mechanisms has come under scrutiny. The introduction of controlled roughness on the hot and/or cold plates is one way of investigating how a modification of the boundary condition impacts the thermal boundary layer. We present direct measurement of the temperature field in a quasi-2D Rayleigh-Bénard turbulent convection cell using Laser-Induced Fluorescence. Turbulent Rayleigh-Bénard convection is generated in a 41.5 x 41.5 x 10 cm rectangular PMMA convection cell filled with deionized water, already used in previous studies2,3. The top plate is entirely smooth, while the bottom one features roughness in the form of an array of 2 mm-high, 5 mm squares, evenly spaced by 1 cm. The top plate is cooled down with a liquid circulation, and the bottom one is heated through Joule effect. The temperature of the two plates is measured with PT100 temperature probes. In addition, another PT100 probe is inserted into the bulk of the flow, giving us the bulk temperature. In this study, he temperature difference between the plates is 26°C, the Rayleigh number is Ra=5.4×1010 and the Nüsselt number is Nu=240. The difference in plate roughness allows the comparison of the effect of roughness on turbulent convection in a single system. LIF gives us access experimentally to the instantaneous temperature field within the cell. We show that the roughness modifies the thermal fluctuations close to them. We also present thermal plume statistics emissions that show differences in their behavior close to the smooth and rough plates.
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Dates et versions

hal-04303114 , version 1 (23-11-2023)

Identifiants

  • HAL Id : hal-04303114 , version 1

Citer

Clément Toupoint, Francesca Chillà, Sylvain Joubaud, Hervé Pabiou, Wandrille Ruffenach, et al.. Thermal plumes in turbulent Rayleigh-Bénard convection using Laser-Induced Fluorescence. 14th European Fluid Mechanics Conference, Sep 2022, Athens & Nafplio, Greece. ⟨hal-04303114⟩
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