Nanofluids — fluids with unprecedented stability of suspension nanoparticles — have attractive features such as high thermal conductivities at very low nanoparticle concentrations, strongly temperature-dependent conductivity, and three-fold higher critical heat flux compared to base fluids. These features are not explained by traditional theories of solid/liquid suspensions, such as Maxwell’s theory or other macroscale approaches. Recently, Jang and Choi’s model has led to the discovery, primarily by extending Einstein’s theory of Brownian motion to energy transport in nanofluids, that Brownian motion of nanoparticles at the molecular and nanoscale level is a dominant mechanism governing their thermal behavior. In this paper we describe a theoretical model for controlling the motion of nanoparticles in nanofluids by means of an electric field and an analytical solution for particle motions in nanofluids. We show that the motion of nanoparticles can be controlled by use of an AC field and that the size and zeta potential of the nanoparticles are the key parameters to control nanoparticle motion beyond Brownian motion.

1.
Eastman
J. A.
,
Choi
S. U. S.
,
Li
S.
,
Yu
W.
, and
Thompson
L. J.
,
2001
, “
Anomalously increased effective thermal conductivity of ethylene glycol-based nanofluids containing copper nanoparticles
,”
Appl. Phys. Lett.
78
, pp.
718
720
.
2.
Choi
S. U. S.
,
Zhang
Z. G.
,
Yu
W.
,
Lockwood
F. E.
, and
Grulke
E. A.
,
2001
, “
Anomalous thermal conductivity enhancement in nanotube suspensions
,”
Appl. Phys. Lett.
79
, pp.
2252
2254
.
3.
Das
S. K.
,
Putra
N.
,
Thiesen
P.
, and
Roetzel
W.
,
2003
, “
Temperature dependence of thermal conductivity enhancement for nanofluids
,”
ASME J. Heat Transfer
125
, pp.
567
574
.
4.
Patel
H. E.
,
Das
S. K.
,
Sundararajan
T.
,
Nair
A. S.
,
George
B.
, and
Pradeep
T.
,
2003
, “
Thermal conductivities of naked and monolayer protected metal nanoparticle base nanofluids: Manifestation of anomalous enhancement and chemical effects
,”
Appl. Phys. Lett.
83
, pp.
2931
2933
.
5.
You
S. M.
,
Kim
J. H.
, and
Kim
K. H.
,
2003
, “
Effect of nanoparticles on critical heat flux of water in pool boiling heat transfer
,”
Appl. Phys. Lett
83
, pp.
3374
3378
.
6.
J. C. Maxwell, Electricity and Magnetism, Claredon Press, Oxford UK (1873).
7.
Jang
S. P.
and
Choi
S. U. S.
,
2004
, “
Role of Brownian motion in the enhanced thermal conductivity of nanofluids
,”
Appl. Phys. Lett.
84
, pp.
4316
4318
.
8.
A. Einstein, Investigation on the Theory of Brownian Movement, Dover, New York (1956).
9.
R. F. Probstein, Physicochemical Hydrodynamics, Butterworth Publishers, USA (1989).
10.
Wang
D.
,
Sigurdson
M.
, and
Meinhart
C. D.
,
2005
, “
Experimental analysis of particle and fluid motion in ac electrokinetics
,”
Exp. Fluids
38
, pp.
1
10
.
11.
Kadaksham
A. T. J.
,
Singh
P.
, and
Aubry
N.
,
2004
, “
Dielectrophoresis of nanoparticles
,”
Electrophoresis
25
, pp.
3625
3632
.
12.
Ramos
A.
,
Morgan
H.
,
Green
N. G.
, and
Castellanos
A.
,
1998
, “
AC electrokinetics: A review of force in microelectrode structures
,”
J. Phys. D: Appl. Phys.
31
, pp.
2338
2353
.
13.
P. J. Burke, 2003, “Nanodielectrophoresis: Electronic nanotweezers,” Encyclopedia of nanoscience and nanotechnology X, pp. 1–19.
14.
Climent
E.
,
Maxey
M. R.
, and
Karniadakis
G. E.
,
2004
, “
Dynamics of self-assembled chaining in magnetorheological fluids
,”
Langmuir
20
, pp.
507
513
.
This content is only available via PDF.
You do not currently have access to this content.