Eur. Phys. J. B 48, 439-444 (2005)
https://doi.org/10.1140/epjb/e2005-00419-5

Multipole polarizability of a graded spherical particle

¹ Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, P.R. China
² Biophysics and Statistical Mechanics Group, Laboratory of Computational Engineering, Helsinki University of Technology, P. O. Box 9203, 02015 HUT, Finland
³ Department of Physics, Fudan University, Shanghai 200433, P.R. China
⁴ Institute of Theoretical Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, P.R. China
⁵ College of Information Science and Technology, East China Normal University, Shanghai 200 062, P.R. China

Corresponding author: ^a kwyu@phy.cuhk.edu.hk

Received: 25 June 2005
Revised: 8 November 2005
Published online: 23 December 2005

Abstract

We have studied the multipole polarizability of a graded spherical particle in a nonuniform electric field, in which the conductivity can vary radially inside the particle. The main objective of this work is to access the effects of multipole interactions at small interparticle separations, which can be important in non-dilute suspensions of functionally graded materials. The nonuniform electric field arises either from that applied on the particle or from the local field of all other particles. We developed a differential effective multipole moment approximation (DEMMA) to compute the multipole moment of a graded spherical particle in a nonuniform external field. Moreover, we compare the DEMMA results with the exact results of the power-law graded profile and the agreement is excellent. The extension to anisotropic DEMMA will be studied in an Appendix.