Combining molecular dynamics and lattice Boltzmann simulations: a hierarchical computational protocol for microfluidics

AO Pereira and LS Lara and CR Miranda, MICROFLUIDICS AND NANOFLUIDICS, 20, 36 (2016).

DOI: 10.1007/s10404-016-1704-7

A hierarchical computational protocol is introduced to investigate the role of interfacial and wetting properties to the fluid displacement in hydrophilic pore network models (PNMs). Based on the combination of molecular dynamics (MD) and lattice Boltzmann method (LBM) simulations at both nano-and microscales, we study the role of dispersed functionalized SiO2 nanoparticles (NP) in brine to the oil displacement process in a clay (montmorillonite-MMT) pore structure. Our MD calculations indicate that dispersion of NP, with different hydrophilic properties, in brine solution reduces the interfacial tension between oil and brine, followed by an increase in the contact angle. The lowest interfacial tension and highest contact angle are for the hydrophilic NP functionalized with polyethylene glycol groups. By mapping the properties obtained from MD into LBM simulation parameters, we explore the oil displacement process in hydrophilic PNMs at the micro-scale. For all systems, the Young-Laplace filling rules are obeyed and, due to the finger formation, the displacement efficiency decreases as the capillary number increases. It was observed that, with the inclusion of NP, a reduction in interfacial tension associated with an increase in the contact angle may enhance the oil displacement process in hydrophilic pore systems at the microscale. The proposed computational protocol can be a versatile tool to explore the potentialities of chemical additives, such as NP, for the oil recovery process and investigate the effects of interfacial tension and wetting properties on the fluid behavior at both nano- and microscales.

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