Static and dynamic measurements of the Nusselt number in turbulent convection

Autor:	J J Niemela
Rok vydání:	2013
Předmět:	Natural convection Materials science Steady state Thermodynamics Film temperature Mechanics Heat transfer coefficient Condensed Matter Physics Nusselt number Churchill–Bernstein equation Atomic and Molecular Physics and Optics Physics::Fluid Dynamics Heat flux Heat transfer Mathematical Physics
Zdroj:	Physica Scripta. :014059
ISSN:	1402-4896 0031-8949
DOI:	10.1088/0031-8949/2013/t155/014059
Popis:	Measurements of the dimensionless heat transfer rate, or Nusselt number Nu, are typically made by static measurements of the heat flux and the average resulting temperature difference across a horizontal layer of fluid under steady state conditions. Here, we describe a dynamic method that uses the properties of a heat wave generated by sinusoidally modulating the boundary temperatures to calculate the Nusselt number from measured temperature fluctuations in the bulk. A comparison with static methods shows excellent agreement within 2% for Ra 109 for cells of aspect ratios 1 and 4, having different heights and for significant variations in frequency and amplitude of the modulation. This excellent agreement breaks down for well-developed turbulent convection at larger Ra 1013.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::6edc2020d1639a21fb9f44fcd36ce088 https://doi.org/10.1088/0031-8949/2013/t155/014059 Zobrazit plný text záznamu