  We consider a system of nonlinear partial differential equations describing
the motion of an incompressible chemically reacting generalized Newtonian fluid
in three space dimensions. The governing system consists of a steady
convection-diffusion equation for the concentration and a generalized steady
power-law-type fluid flow model for the velocity and the pressure, where the
viscosity depends on both the shear-rate and the concentration through a
concentration-dependent power-law index. The aim of the paper is to perform a
mathematical analysis of a finite element approximation of this model. We
formulate a regularization of the model by introducing an additional term in
the conservation-of-momentum equation and construct a finite element
approximation of the regularized system. We show the convergence of the finite
element method to a weak solution of the regularized model and prove that weak
solutions of the regularized problem converge to a weak solution of the
original problem.
