Rheological properties of nanofluids flowing through microchannels

Abstract

Results on the viscosity of Si O2 nanofluids submitted to very strong shear rates are reported. Experiments were conducted with micromachined capillary viscometers equipped with local pressure probes. For particle sizes of 35, 94, and 190 nm, and solid volume fractions from 1.4% to 7%, a Newtonian behavior has been observed up to 5× 104 s-1. The increase in the nanofluid viscosity obeys a classical model but with a crowding factor which is a function of the diameter of the particles. This size dependence is explained by the influence of the shearing motion on the aggregates aspect ratio. © 2007 American Institute of Physics.