Numerical Simulation Of Brownian Particles Based On Stochastic Eulerian Lagrangian Method

The study of Brownian motion is a classic problem in the field of micro fluidstructure coupling.Brownian motion of particles in suspensions is widely encountered in nature and science.The motion of Brownian particles is mainly affected by the interactions between particles and hydrodynamic effects.The research is investigated by a thermostat based on fluctuating hydrodynamics for dynamic simulations of implicit-solvent coarse-grained model which can take into account both hydrodynamic and Brownian effects.The Stochastic Eulerian Lagrangian Method(SELM)is used to simulate the motion of Brownian particles in suspension.Particles with hard sphere(cutand-shifted Lennard-Jones)and soft sphere(Gaussian-core potential)are studied.Three diffusion regimes with different characteristics are observed ballistic motion,short-time diffusion and long-time diffusion for both models.For the hard sphere model,the shorttime self-diffusion coefficient decrease monotonously with the increase of volume fraction which is consistent with the results of the experiment.However,for the soft sphere model,the self-diffusion coefficient as a function of dimensional density appears to be nonmonotonic.It shows that the long-time self-diffusion coefficient decreases monotonically when dimensional density is below 0.3,and then increases anomalously when it passes through 0.3.Similar results are obtained for rod-shaped particles.The influence of the particle density on the viscosity of the suspension are also studied and compared with the previous results.