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 proc esses of a suspension of particles with internal rotation in a viscoel astic fluid. The system of constitutive equations may be particularize d to obtain several cases mentioned before in the literature as those given by Shliomis, Eringen, and Brenner. A qualitative discussion abou t 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 visc osity in the case where the velocity is not coupled with the mass pola rization, It is shown that for some values of the parameters the subsy stems of the fluid and the collection of particles with spin may act i ndependently, but for other values they can have a mutual interchange of energy, Moreover, to present a flow solution where the coupling dyn amics appears explicitly, an example is given for the flow of a nonvis coelastic fluid suspension down an inclined plane, It is shown that th e 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.