  The dynamics of elastic dumbbells in linear shear flow is investigated by
fluid particle dynamics simulations at small Reynolds numbers. The positive
contribution of a single dumbbell to the effective shear viscosity is
determined via the extra stress exerted at the boundaries of the shear cell and
the difference to the contributions obtained via the Kramers-Kirkwood formula
are described. For a small Weissenberg number and when the mean dumbbell length
becomes larger than the mean next-neighbor distance, the contribution of
interacting dumbbells to the mean shear viscosity exceeds significantly the
contribution of unconnected beads occupying the same volume fraction.
