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Natural convection of microparticle suspensions in thin enclosures. (English) Zbl 1255.76003
Summary: Natural convection experiments are performed with aluminum oxide microparticle aqueous suspensions in thin enclosures of circular planform at angles of inclination to the horizontal of 90$$^\circ$$, 30$$^\circ$$ and 0$$^\circ$$. The average size of the aluminum oxide particles is about 250 nm, and volume fractions of 1.31% and 2.72% are used. The aspect ratio varies from 50.7 to 10.9, and the maximum Raleigh number was $$3 \times 10^{5}$$. No effect of particles on the Nusselt number-Rayleigh number relation is found for the vertical enclosure at 90$$^\circ$$. However at 30$$^\circ$$ and 0$$^\circ$$ (horizontal) there is a decrease in Nusselt number compared to pure water, which is pronounced at lower Rayleigh number and higher particle concentrations. This anomalous behavior is attributed to sedimentation.

##### MSC:
 76-05 Experimental work for problems pertaining to fluid mechanics 76R10 Free convection 80A20 Heat and mass transfer, heat flow (MSC2010) 76T20 Suspensions
##### Keywords:
natural convection; microparticle; sedimentation; thermophoresis
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##### References:
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