Open Access Nano Review

Numerical study of instability of nanofluids: the coagulation effect and sedimentation effect

Yu Ni, JianRen Fan* and YaCai Hu

Author Affiliations

State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, P. R. China

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Nanoscale Research Letters 2011, 6:183  doi:10.1186/1556-276X-6-183

Published: 28 February 2011

Abstract

This study is a numerical study on the coagulation as well as the sedimentation effect of nanofluids using the Brownian dynamics method. Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids. The rms fluctuation of the particle number concentration, as well as the flatness factor of it, is employed to study the formation and variation of the coagulation process. The results indicate a superposition of coagulation and sedimentation effect of small nano-particles. Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids. In addition, the effect of ζ potentials is against the formation of coagulation and positive to the stability of nanofluids.