Study of nanofluid natural convection phenomena in rectangular enclosures

Kau Fui V. Wong, Bradley L. Bon, Santina Vu, Sing Samedi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Scopus citations


Buoyancy induced flows in rectangular enclosures using nanofluids were investigated. The effects of mass fraction concentration of nanoparticles, enclosure aspect ratio and inclination were observed. The nanofluid under investigation was a water-based alumina nanofluid. Since water exhibits an anomalous density extremum near 4°C the additional effect of buoyancy force reversal will also be observed. The opacity of nanofluid does not permit the use of particle image velocimetry, laser induced fluorescence or any other means of flow visualization or visual temperature measurement of the local fluid temperature. Therefore to investigate the temperature field a non-invasive method, namely ultrasound thermometry, will be used to observe the temperature field. The experimental enclosure was validated using water as the initial fluid; measured values of the local fluid temperature were compared with numerical simulations utilizing COMSOL Multiphysics. Nanofluid mass fractions of 10% and 25% were used for comparative purposes of the effects of concentration on the temperature field. Buoyancy force reversal effects were witnessed in both 10% and 25% concentrations. The nanofluid also prolonged the multicellular effects that occur in buoyancy inversion flows. A Rayleigh number inversion was observed for the 25% mass fraction nanofluid. The multicellular regime transitions to boundary layer regime at about Ra=1E+07 when the aspect ratio is 2.625 and at about Ra=2E+08 when the aspect ratio is 1.000, for different concentrations of nanofluid. For these concentrations of nanofluid and aspect ratio equal to 2.625, instability in the core region occurred at about Ra=1.2E+07.

Original languageEnglish (US)
Title of host publicationEnergy Systems
Subtitle of host publicationAnalysis, Thermodynamics and Sustainability
PublisherAmerican Society of Mechanical Engineers (ASME)
Number of pages11
ISBN (Electronic)0791843009
StatePublished - 2007
EventASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007 - Seattle, United States
Duration: Nov 11 2007Nov 15 2007

Publication series

NameASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)


OtherASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Mechanical Engineering


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