Phase Separation and Coexistence of Hydrodynamically Interacting Microswimmers

摘要: A striking feature of the collective behavior spherical microswimmers is that for sufficiently strong self-propulsion they phase-separate into a dense cluster coexisting with low-density dis- ordered surrounding. Extending our previous work, we use squirmer as model swimmer and particle-based simulation method multi-particle collision dynamics to explore influence hydrodynamics on their phase in quasi-two-dimensional geometry. The coarsening towards phase-separated state diffusive an intermediate time regime followed by final ballistic compactification cluster. We determine binodal lines diagram Peclet number versus density. Interestingly, gas binodals are shifted smaller densities increasing mean density or dense-cluster size, which explain using recently introduced pressure balance [S. C. Takatori et al., Phys. Rev. Lett. 113, 028103 (2014)] extended hydrodynamic contribution. Furthermore, find pushers pullers line larger numbers compared neutral squirmers. Finally, when lowering number, transforms from hexagonal "solid" disordered "fluid" state.