  Simulations of over $10^3$ hydrodynamically coupled solid spheres are
performed to investigate collective motion of linear trains and regular square
arrays of particles suspended in a fluid bounded by two parallel walls. Our
novel accelerated Stokesian-dynamics algorithm relies on simplifications
associated with the Hele--Shaw asymptotic far-field form of the flow scattered
by the particles. The simulations reveal propagation of particle-displacement
waves, deformation and rearrangements of a particle lattice, propagation of
dislocation defects in ordered arrays, and long-lasting coexistence of ordered
and disordered regions.
