Relaxation phenomena in viscoelastic colloidal suspensions with internal rotation

In this paper, extended irreversible thermodynamics is used to obtain the constitutive equations which govern the motion and relaxation processes of a suspension of particles with internal rotation in a viscoelastic fluid. The system of constitutive equations may be particularized to obtain several cases mentioned before in the literature as those given by Shliomis, Eringen, and Brenner. A qualitative discussion about macroscopic mass polarization diffusion is presented, The linearized constitutive equations, together with the linear momentum and angular momentum equations, are the stand point to calculate the complex viscosity in the case where the velocity is not coupled with the mass polarization, It is shown that for some values of the parameters the subsystems of the fluid and the collection of particles with spin may act independently, but for other values they can have a mutual interchange of energy, Moreover, to present a flow solution where the coupling dynamics appears explicitly, an example is given for the flow of a nonviscoelastic fluid suspension down an inclined plane, It is shown that the velocity depends linearly on the mass polarization through which the couplings control the form and magnitude of the velocity profile. (C) 1996 Academic Press, Inc.