Dynamical properties of dense magnetic suspensions

Dynamical response functions to an external magnetic field as well as rheol ogical properties of moderately concentrated magnetic colloids have been ca lculated by methods of statistical physics. Hydrodynamic and magnetodipole interactions between the particles were taken into account. We suppose that ferroparticle magnetic moment is constant in its absolute value and is fro zen into the particle body. Our analysis has shown that the magnetodipole i nteraction increases magnetic response functions and rheological parameters of the colloid as well as characteristic relaxation times of both colloid magnetization and hydrodynamic stress. We have studied some pecularities of hydrodynamical behaviour of the ferrocolloid in an oscillating magnetic fi eld. (C) 1999 Elsevier Science B.V. All rights reserved.