Colloidal Dynamics Simulations of Rheology and Stability of Concentrated Fuel Slurries

摘要

This report presents the results of a Phase I SBIR project to calculate properties of concentrated colloidal suspensions using computer simulation methods. Equilibrium and nonequilibrium Brownian dynamics (NEBD) simulations were performed for concentrated aqueous and nonaqueous colloidal suspensions. These are the first calculations of suspension shear viscosity based on NEBD simulations. Stability estimates were also made for sterically stabilized nonaqueous suspensions. The NEBD calculations provide quantitative evidence for the disturbance of the equilibrium structure of the dispersions by shearing. Shear viscosities have been calculated as a function of shear rate and particle volume fraction. Good agreement was obtained with experimental viscosities for comparable systems. The simulation results are sensitive to the type, strength and range of the potential interactions used to describe the dispersion. These results demonstrate that the NEBD technique is capable of describing the essential features of sheared suspension behavior. They also establish the feasibility and desirability of using NEBD simulation methods as a predictive engineering tool for the design of slurries. Keywords: Colloidal dynamics, Rheology, Fuel slurries, Computer simulation.