[SY-O3] Coarse-Grain Simulations of Polymer Solutions with Hydrodynamics and Long-range Interactions
Polymer solution is used as lubricant in Tribological purpose. Viscosity index improver is used to normalize temperature dependence of viscosity of the lubrication oil. Here we show our numerical simulation approach to investigate the dynamics of polymer solution. The numerical scheme is for simulating the dynamics of suspensions of Brownian particles, coupling molecular motion treated by Langevin equation and hydro-dynamics treated by lattice Boltzmann method.
In order to simulate bulk properties of polymers under shear, we apply periodic external field so that to make shear field. The external force is applied to the fluid dynamics part. Polymer is dragged to the region where the shear force is strongest, and changes its shape. The structure change is described by the radius of gyration which decreases with time.
In order to describe confined system, non-slip boundary is adopted in bottom line and moving wall is set in top line. During the simulation, the polymer are pull to upper layer where the shear field is large. To show the orientation of the molecule, order parameter is calculated. Due to the effect of external field, the orientation of the polymers changed to the direction of the shear force.
In above simulation, the chemical properties of the polymers are not discussed. We simulate the equilibrium structure of polymer using point dipole interactions. We use Monte Carlo Brownian Dynamics method for time integration.The radius of gyration of non-polar polymers are same as analytical theory. The structure of the polymers with functional groups is calculated. The interaction between functional groups make tight structure in low temperature and show high viscosity index than non-polar polymers. The polar polymer shows strong initial distribution dependence.
In order to simulate bulk properties of polymers under shear, we apply periodic external field so that to make shear field. The external force is applied to the fluid dynamics part. Polymer is dragged to the region where the shear force is strongest, and changes its shape. The structure change is described by the radius of gyration which decreases with time.
In order to describe confined system, non-slip boundary is adopted in bottom line and moving wall is set in top line. During the simulation, the polymer are pull to upper layer where the shear field is large. To show the orientation of the molecule, order parameter is calculated. Due to the effect of external field, the orientation of the polymers changed to the direction of the shear force.
In above simulation, the chemical properties of the polymers are not discussed. We simulate the equilibrium structure of polymer using point dipole interactions. We use Monte Carlo Brownian Dynamics method for time integration.The radius of gyration of non-polar polymers are same as analytical theory. The structure of the polymers with functional groups is calculated. The interaction between functional groups make tight structure in low temperature and show high viscosity index than non-polar polymers. The polar polymer shows strong initial distribution dependence.