  A highly accurate method for simulating surfactant-covered droplets in
two-dimensional Stokes flow with solid boundaries is presented. The method
handles both periodic channel flows of arbitrary shape and stationary solid
constrictions. A boundary integral method together with a special quadrature
scheme is applied to solve the Stokes equations to high accuracy, also for
closely interacting droplets. The problem is considered in a periodic setting
and Ewald decompositions for the Stokeslet and stresslet are derived.
Computations are accelerated using the spectral Ewald method. The time
evolution is handled with a fourth order, adaptive, implicit-explicit
time-stepping scheme. The numerical method is tested through several
convergence studies and other challenging examples and is shown to handle drops
in close proximity both to other drops and solid objects to high accuracy.
