Heat convection in water can be suppressed by adding a small amount of highly thermophilic nanoparticles. We show that such suppression is not effective when a suspension with uniform concentration of nanoparticles 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 / Donzelli, Gea; Cerbino, Roberto; Vailati, Alberto. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 102:(2009), pp. 104503-104503. [10.1103/PhysRevLett.102.104503]
Bistable heat transfer in a nanofluid
DONZELLI, GIAN PAOLO;
2009
Abstract
Heat convection in water can be suppressed by adding a small amount of highly thermophilic nanoparticles. We show that such suppression is not effective when a suspension with uniform concentration of nanoparticles 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.I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.