  We have developed numerical simulations of three dimensional suspensions of
active particles to characterize the capabilities of the hydrodynamic stresses
induced by active swimmers to promote global order and emergent structures in
active suspensions. We have considered squirmer suspensions embedded in a fluid
modeled under a Lattice Boltzmann scheme. We have found that active stresses
play a central role to decorrelate the collective motion of squirmers and that
contractile squirmers develop significant aggregates.
