  The article describes parallel multiphysics simulations of charged particles
in microfluidic flows with the waLBerla framework. To this end, three physical
effects are coupled: rigid body dynamics, fluid flow modelled by a lattice
Boltzmann algorithm, and electric potentials represented by a finite volume
discretisation. For solving the finite volume discretisation for the
electrostatic forces, a cell-centered multigrid algorithm is developed that
conforms to the lattice Boltzmann meshes and the parallel communication
structure of waLBerla. The new functionality is validated with suitable
benchmark scenarios. Additionally, the parallel scaling and the numerical
efficiency of the algorithms are analysed on an advanced supercomputer.
