The effect of complex permeability and agglomeration on composite magnetic systems: A three-dimensional numerical analysis and comparison with analytical models

Magnetic permeability of a composite is investigated using three-dimensional numerical models for static and quasistatic case. To analyze the effect of agglomeration and imaginary part of intrinsic permeability on the effective permeability, inclusions with complex permeability and having random distribution or random distribution with agglomeration were used. Significant deviation of analytical effective medium and Maxwell-Garnett models from numerical results for imaginary part of permeability was observed. We obtained that agglomeration increases the real part of the effective permeability for higher volume fractions and higer intrinsic permeabilities. The effect of agglomeration is even more pronounced for the imaginary part of the effective permeability. Our results thus show that agglomeration and complex intrinsic permeability could explain experimentally observed effective permeability. (C) 2008 American Institute of Physics.