In this work, we seek to develop a new interatomic potential for α-Fe that is able to rationalize experimental flow stress data. We generate a series of potentials with similar bulk and point defect properties, but exhibit different energetic landscapes for the Peierls potential. The family of potentials all possess a compact core structure, which we find necessitates a camel-hump shaped Peierls potential. Within this constraint, we analyze the relationships between the Peierls potential, the 3-D kink nucleation energetics, and the resulting shape of the kink structures for the screw dislocation. We find that one of our models, labeled MPG20, gives very good agreement with experimental flow stress data over the entire stress range considered.

We explore the ability of a modified form of an n-6 potential to represent transport property data of n-paraffins over a range of temperatures, pressures, and chain lengths. General features of the relationship between the potential form and resulting properties are investigated for methane, where it is shown that the tunable softness of the potential function allows for adjustment of transport properties, through modulation of the magnitude of the density fluctuations, while leaving thermodynamic properties such as liquid density and vapor-liquid coexistence properties essentially unchanged. We tune potential parameters of a united atom model for n-paraffins to viscosity and density data of low molecular weight (C4–C10) species and demonstrate the robust predictive capability of viscosity-temperature-pressure relationships for species up to n-C36.

A novel variant of the Material Point Method is proposed to solve flow problems for incompressible viscoelastic fluids. As in the original spirit of the method, material points possess all necessary information about the material constitutive behavior and move with the flow. They are additionally employed as integration points, whose weights are computed as the system evolves in order to ensure exact integration of the discretized conservation equations. The method is shown to achieve quadratic convergence for transient start-up flow of the Oldroyd-B fluid. In addition, we apply the method to flow of a Giesekus fluid in concentric rotating cylinders, and in flow through an abrupt 4:1 contraction, comparing favorably to available analytical, experimental, and simulation results as appropriate.