A multiscale method for simulating fluid interfaces covered with large molecules such as asphaltenes

TL;DR

This paper introduces a multiscale simulation approach combining nanoscale molecular dynamics and macroscale flow modeling to study complex fluid interfaces with asphaltenes, revealing new insights into interface behavior and crumpling phenomena.

Contribution

The paper develops the first multiscale method integrating detailed molecular dynamics with advanced macroscale flow simulations for asphaltene-covered interfaces.

Findings

Validated nanoscale interfacial properties for asphaltenes.

Reproduced experimentally observed crumpling of water drops.

Provided new physical explanations for interface behavior with asphaltenes.

Abstract

(Abbreviated) In this paper we report on the development of a multiscale method for simulating complex liquid-liquid systems such as water in contact with oil containing asphaltenes. We consider simulations where water drops covered with asphaltenes are deflated, and reproduce the crumpling observed in experiments. The method on the nanoscale is based on using coarse-grained molecular dynamics simulations of the interface, with an accurate model for the asphaltene molecules. This enables the calculation of interfacial properties. These properties are then used in the macroscale simulation, which is performed with a two-phase incompressible flow solver using a novel hybrid level-set/ghost-fluid/immersed-boundary method for taking the complex interface behaviour into account. We validate both the nano- and macroscale methods. Results are presented from nano- and macroscale simulations which showcase some of the interesting behaviour caused by asphaltenes affecting the interface. The molecular simulations presented here are the first in the literature to obtain the correct interfacial orientation of asphaltenes. Results from the macroscale simulations present a new physical explanation of the crumpled drop phenomenon, while highlighting shortcomings in previous hypotheses.