(346bd) Development of a Novel Method for Upscaling Molecular Dynamics to Coarse-Grained Models

Recent scientific work has shown that subsurface deposits of hydrocarbons in shale exhibit thermodynamic and flow behavior inconsistent with equations of state for bulk mixtures. Understanding fluid properties ranging from the nanometer to micron scales is important in enhanced oil recovery as well as other mesoscale flow systems. Molecular Dynamics (MD) simulation is an indispensable tool for determining the characteristics of confined fluid systems such as those encountered in shale oil deposits. However, performing MD computations for micron scale systems is currently not feasible on most computational resources. One means of overcoming this challenge is the use of Dissipative Particle Dynamics (DPD), a semi-empirical class of models specifically targeting mesoscale systems. Proper application of DPD models requires calibration of a number of parameters from data obtained experimentally or through MD simulations.

In this work, we establish a method of calibrating DPD model parameters from MD data, specifically, by computing a set of local thermodynamic and transport properties and optimizing DPD parameters from spatially filtered properties. MD datasets for both bulk heptane and heptane confined in a silica pore are considered. Additionally, we assess several functional forms for the DPD force kernel by comparing their a priori and a posteriori predictions of system properties.