  Methods for building a consistent interface between hydrodynamic and
simulation modules is presented. These methods account for the backflow across
the hydrodynamic/simulation hyper-surface. The algorithms are efficient,
relatively straight-forward to implement, and account for conservation laws
across the hyper-surface. The methods also account for the spurious
interactions between particles in the backflow and other particles by following
the subsequent impact of such particles. Since the number of altered
trajectories grows exponentially in time, a cutoff is built into the procedure
so that the effects of the backflow are ignored beyond a certain number of
collisions
