Abstract
Molecular analysis of viscosity index improver polymers are investigated by multiphysics simulations. Polymer segment motion is described by Langevin dynamics. Flow of base oil is calculated solving Navier-Stokes equation by lattice Boltzmann method. The force between the polymer segments and solvent base oil is calculated by Stokes force applying on the center of the mass of polymer segments, using the mean velocity from the fluids. In bulk solution under shear, the inversed temperature dependence of the radius of gyration of polymers are found. Under no-shear system, the radius of gyration increases with the polymer weight increases, whereas the reverse dependence is found in the shear case. In confined solution under shear, given by the movement of a solid wall, the polymer molecules moved to the solid wall direction, due to the lift force. This means, not only the inter-molecular force but the hydrodynamic force is important to understand the viscosity improving and adsorption process.
