TY - JOUR
T1 - Electric field-driven formation of particle concentration fronts in suspensions
AU - Kumar, Anil
AU - Acrivos, Andreas
AU - Khusid, Boris
AU - Jacqmin, David
N1 - Funding Information:
We would like to acknowledge Rohit A. Ingale for his help in the preparation of the manuscript. This work was supported in part by Grants from NASA (NAG3-2698), NSF (CTS-0307099), and NSF/Sandia (NIRT/NER-0330703) (B.K).
PY - 2007/1
Y1 - 2007/1
N2 - A distinct front, separating regions enriched with and depleted of particles, was recently observed in suspensions subjected to high-gradient ac electric fields and a set of theoretical model equations for the particle concentration, containing no fitting parameters, were developed [Kumar et al., 2004. Combined negative dielectrophoresis and phase separation in nondilute suspensions subject to a high-gradient ac electric field. Phys. Rev. E 69, 021402-1-10; Bennett et al., 2003. Combined field-induced dielectrophoresis and phase separation for manipulating particles in microfluidics. Appl. Phys. Lett. 83, 4866-4868]. Although the numerical solutions of these equations were found to be quantitatively consistent with the experimental observations, they did not provide sufficient information for elucidating the mechanism of the front formation due to the complexity of the equations. Here, we examine these equations analytically for the special case in which they admit a similarity solution and establish the existence of shock solutions to these equations. The shocks are shown to arise because of the rapid local growth of the suspension viscosity due to the field-driven particle accumulation in certain areas of the domain.
AB - A distinct front, separating regions enriched with and depleted of particles, was recently observed in suspensions subjected to high-gradient ac electric fields and a set of theoretical model equations for the particle concentration, containing no fitting parameters, were developed [Kumar et al., 2004. Combined negative dielectrophoresis and phase separation in nondilute suspensions subject to a high-gradient ac electric field. Phys. Rev. E 69, 021402-1-10; Bennett et al., 2003. Combined field-induced dielectrophoresis and phase separation for manipulating particles in microfluidics. Appl. Phys. Lett. 83, 4866-4868]. Although the numerical solutions of these equations were found to be quantitatively consistent with the experimental observations, they did not provide sufficient information for elucidating the mechanism of the front formation due to the complexity of the equations. Here, we examine these equations analytically for the special case in which they admit a similarity solution and establish the existence of shock solutions to these equations. The shocks are shown to arise because of the rapid local growth of the suspension viscosity due to the field-driven particle accumulation in certain areas of the domain.
KW - Dielectrophoresis
KW - Electrohydro-dynamics of suspensions
KW - Front formation
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U2 - 10.1016/j.fluiddyn.2006.07.005
DO - 10.1016/j.fluiddyn.2006.07.005
M3 - Article
AN - SCOPUS:33847093792
SN - 0169-5983
VL - 39
SP - 169
EP - 192
JO - Fluid Dynamics Research
JF - Fluid Dynamics Research
IS - 1-3
ER -