Heat convection in water can be suppressed by adding a small amount of highly thermophilic nanoparticles (NP). We show that such suppression is not effective when a suspension with uniform concentration of NP is suddenly heated from below. At Rayleigh numbers smaller than a sample dependent threshold Ra* we observe transient oscillatory convection. Unexpectedly, the duration of convection diverges at Ra* Above Ra* oscillatory convection becomes permanent and the heat transferred exhibits bistability. Our results are explained only partially and qualitatively by existing theories.
Bistable heat transfer in a nanofluid / G. Donzelli, R. Cerbino, A. Vailati. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 102:10(2009 Mar 13), pp. 104503.104503.1-104503.104503.4. [10.1103/PhysRevLett.102.104503]
Bistable heat transfer in a nanofluid
G. DonzelliPrimo
;R. CerbinoSecondo
;A. VailatiUltimo
2009
Abstract
Heat convection in water can be suppressed by adding a small amount of highly thermophilic nanoparticles (NP). We show that such suppression is not effective when a suspension with uniform concentration of NP is suddenly heated from below. At Rayleigh numbers smaller than a sample dependent threshold Ra* we observe transient oscillatory convection. Unexpectedly, the duration of convection diverges at Ra* Above Ra* oscillatory convection becomes permanent and the heat transferred exhibits bistability. Our results are explained only partially and qualitatively by existing theories.Pubblicazioni consigliate
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