Viscosity affected by nanoparticle aggregation in Al2O3-water nanofluids
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
Nanoscale Research Letters 2011, 6:248 doi:10.1186/1556-276X-6-248Published: 22 March 2011
An investigation on viscosity was conducted 2 weeks after the Al2O3-water nanofluids having dispersants were prepared at the volume concentration of 1-5%. The shear stress was observed with a non-Newtonian behavior. On further ultrasonic agitation treatment, the nanofluids resumed as a Newtonian fluids. The relative viscosity increases as the volume concentrations increases. At 5% volume concentration, an increment was about 60% in the re-ultrasonication nanofluids in comparison with the base fluid. The microstructure analysis indicates that a higher nanoparticle aggregation had been observed in the nanofluids before re-ultrasonication.