Methane Flow in Organic Nanotubes of Complex Geometries

MARIANO MARTÍN RAMÍREZ; FEDERICO CASTEZ; EMILIO A. WINOGRAD; VERÓNICA MURIEL SÁNCHEZ

Workshop; Primer Workshop sobre Fenómenos de Transporte y Procesos Fuera del Equilibrio; 2018

Universidad Nacional de General Sarmiento (UNGS)

While in macroscopic pipeline flows the interaction between fluid molecules dominates the flow behavior, in the case of flow in nanochannels, often is the interaction of fluid molecules with the tunnel´s walls which more deeply impacts on the flow properties. Moreover, these nanoscale flows are usually associated with the formation of an adsorbed mobile layer. When the tunnel´s walls are smooth enough, the flow rates are strongly enhanced with respect to the one calculated by the continuum analytical equations (Hagen-Poiseuille, Knudsen diffusion, etc.). To understand this behavior, numerous experimental and numerical studies have been performed.On the numerical side, the Molecular Dynamics technique has emerged as one of the most valuable and promising tools to simulate and understand these systems. Many works consider the flow through pores connected by carbon nanotubes. Regarding the application to many real-life nanochannels (for instance, nanoporous shale rock), whose typical shapes are far more complex than a smooth cylindrical geometry, it is necessary to consider nanochannels with complex geometries. In this context, in this work we apply molecular dynamics to simulate methane flow between pores connected by nanosized channels with different geometrical properties such as tortuosity and surface roughness. In particular, we consider two types of tortuosity: one ´smooth´ (helicoidal type) and another with more abrupt (spline type) variations of the curvature. We found that the flow rate not only decreases as the tortuosity increases but, in addition, curvature variations also impact strongly in the flow rate. On the other hand, we carry out simulations in corrugated tunnels, studying how the flow rate depends on the amplitude and wave-length of the corrugation comparing with the expectations from continuum hydrodynamic models. We compare results from discrete molecular dynamics with results from continuum Lattice-Boltzmann method, using equivalent corresponding nanochannels. Finally, we discuss the application of these results to unconventional hydrocarbon reservoirs (shale type), which are formed by interconnected nanopores with complex geometries.