Convergence Analysis for a Finite Element Approximation of a Steady   Model for Electrorheological Fluids
  In this paper we study the finite element approximation of systems of $p(\cdot)$-Stokes type, where $p(\cdot)$ is a (non constant) given function of the space variables. We derive --in some cases optimal-- error estimates for finite element approximation of the velocity and of the pressure, in a suitable functional setting. 
Luigi C. Berselli, Dominic Breit, Lars Diening
math.NA