Exploration of non-Newtonian flow phenomena encountered in biological fluids, with particular attention to changes that occur close to a solid surface in the flow. This phenomenon is presumed responsible for the appreciable changes in the apparent viscosity when the scale of the flow is not large compared to the particle size. To provide a better understanding of the phenomenon and to predict its effects, an analytic model is developed, which comprises a wall layer and a core whose viscosities are dependent on the respective concentration of particles. Experimental data for the effects of feed concentration and tube diameter on the dynamic tube concentration and on the effective viscosity are used to evaluate the parameters of the analysis. 28 pp. Ref.