In this paper we describe \textsc{PDELab}, an extensible C++ template library for finite element methods based on the Distributed and Unified Numerics Environment (\textsc{Dune}). \textsc{PDELab} considerably simplifies the implementation of discretization schemes for systems of partial differential equations by setting up global functions and operators from a simple element-local description. A general concept for incorporation of constraints eases the implementation of essential boundary conditions, hanging nodes and varying polynomial degree. The underlying \textsc{Dune} software framework provides parallelization and dimension-independence.
Flow of particles suspended in a fluid can be found in numerous industrial processes utilizing sedimentation, fluidization and lubricated transport such as food processing, catalytic processing, slurries, coating, paper manufacturing, particle injection molding and filter operation. The ability to understand rheology effects of particulate flows is elementary for the design, operation and efficiency of the underlying processes. Despite the fact that particle technology is widely used, it is still an enormous experimental challenge to determine the correct parameters for the process employed. In this paper we present \mbox{2-dimensional} numerical results for the behavior of a particle based suspension and compare it with analytically results obtained for the Stokes-flow around a single particle.