Thermal radiation in Rayleigh-Benard convection experiments

0525160 - ÚPT 2021 RIV US eng J - Journal Article
Urban, Pavel - Králík, Tomáš - Hanzelka, Pavel - Musilová, Věra - Věžník, Tomáš - Schmoranzer, D. - Skrbek, L.
Thermal radiation in Rayleigh-Benard convection experiments.
Physical Review E. Roč. 101, č. 4 (2020), č. článku 043106. ISSN 2470-0045. E-ISSN 2470-0053
R&D Projects: GA ČR(CZ) GA20-00918S
Institutional support: RVO:68081731
Keywords : heat-transfer * heat radiation * natural convection * sulfur hexafluoride
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 2.529, year: 2020
Method of publishing: Limited access
https://journals.aps.org/pre/abstract/10.1103/PhysRevE.101.043106

An important question in turbulent Rayleigh-Benard convection (RBC) is the effectiveness of convective heat transport, which is conveniently described via the scaling of the Nusselt number (Nu) with the Rayleigh (Ra) and Prandtl (Pr) numbers. In RBC experiments, the heat supplied to the bottom plate is also partly transferred by thermal radiation. This heat transport channel, acting in parallel with the convective and conductive heat transport channels, is usually considered insignificant and thus neglected. Here we present a detailed analysis of conventional far-field as well as strongly enhanced near-field radiative heat transport occurring in various RBC experiments. A careful inclusion of the radiative transport appreciably changes the Nu = Nu(Ra) scaling inferred in turbulent RBC experiments near ambient temperature utilizing gaseous nitrogen and sulfur hexafluoride as working fluids. On the other hand, neither the conventional far-field radiation nor the strongly enhanced near-field radiative heat transport appreciably affects the heat transport law deduced in cryogenic helium RBC experiments.
Permanent Link: http://hdl.handle.net/11104/0309358