  Multiparticle collision dynamics (MPC), a particle-based mesoscale simulation
technique for com- plex fluid, is widely employed in non-equilibrium
simulations of soft matter systems. To maintain a defined thermodynamic state,
thermalization of the fluid is often required for certain MPC variants. We
investigate the influence of three thermostats on the non-equilibrium
properties of a MPC fluid under shear or in Poiseuille flow. In all cases, the
local velocities are scaled by a factor, which is either determined via a local
simple scaling approach (LSS), a Monte Carlo-like procedure (MCS), or by the
Maxwell-Boltzmann distribution of kinetic energy (MBS). We find that the
various scal- ing schemes leave the flow profile unchanged and maintain the
local temperature well. The fluid viscosities extracted from the various
simulations are in close agreement. Moreover, the numerically determined
viscosities are in remarkably good agreement with the respective theoretically
predicted values. At equilibrium, the calculation of the dynamic structure
factor reveals that the MBS method closely resembles an isothermal ensemble,
whereas the MCS procedure exhibits signatures of an adi- abatic system at
larger collision-time steps. Since the velocity distribution of the LSS
approach is non-Gaussian, we recommend to apply the MBS thermostat, which has
been shown to produce the correct velocity distribution even under
non-equilibrium conditions.
