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Title: Anomalous size dependent rheological behavior of alumina based nanofluids
Authors: Singh, PK
Anoop, KB
Patel, HE
Sundararajan, T
Pradeep, T
Das, SK
2nd Micro and Nano Flows Conference (MNF2009)
Keywords: Nanofluids;Alumina suspensions;Shear induced particle migration;Rheology of suspensions;Viscosity of suspensions
Issue Date: 2009
Publisher: Brunel University
Citation: 2nd Micro and Nano Flows Conference, Brunel University, West London, UK, 01-02 September 2009
Abstract: Rheological behaviour of Alumina (Al2O3) based nanofluids (NFs) has been studied and found to be exhibit unexpected behaviour. Two base-fluids viz, water and ethylene glycols (EG). Three particle sizes (11, 45 and 150 nm), varying over an order of magnitude, were used to analyze the effect of particle size. The experimental data has shown typical Newtonian behavior for both W based and EG based alumina NFs The viscosity of EG based NFs is found to be anomalously reduced compared to the base fluid. This reduction in viscosity may be due to hygroscopic nature of EG or due to the presence of water in as-received high concentration sample also, as told by some researchers. However, this phenomenon was absent for water based NFs. The inter-related effects of particle size, concentration and mode of dispersion (mono or poly-dispersed) were investigated. To eliminate the effect of size variation, mono dispersed NFs are obtained by centrifuging and re-suspension of parent NFs. Particle migration under shear is attributed to the reduction of viscosity. The increase in bulk viscosity with particle size reduction is attributed to the surface forces acting between the particles and the medium in a suspension.
Description: This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.
ISBN: 978-1-902316-72-7
Appears in Collections:Brunel Institute for Bioengineering (BIB)
The Brunel Collection

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