Experimental investigation of nanofluid shear and longitudinal viscosities

Schmidt, A., Chiesa, M., Torchinsky, D., Johnson, J., Boustani, A., Nelson, K.A., McKinley, G.H. and Chen, G.

Dilute nanoparticle suspensions of alumina in decane and isoparaffinic polyalphaolefin  PAO
exhibit thermal conductivity and shear viscosity that are enhanced compared to continuum models
that assume well-dispersed particles. An optical technique has been used to measure the longitudinal
viscosity of these suspensions at frequencies from 200 to 600 MHz and evaluate an effective
hydrodynamic particle size. The measurements indicate that for the decane-based nanofluids the
nanoparticles do not form clusters. In the case of PAO nanofluids, the measurements of longitudinal
viscosity and the corresponding values of the particle size are consistent with a picture of
nonclustered particles in a weakly shear-thinning viscous oligomeric oil.