Methane flow in nanopores: Analytical approximation based on MD simulations

Abstract

In the current study by means of molecular dynamics (MD) computer simulation, we have investigated pressure-driven flow of methane at high temperature and pressures (398.15 K and 400–500 bar) in circular, square, and triangular nanopores of different size and different fluid–wall interaction strength. To generalize the results obtained in MD simulation, we have proposed an analytical approximation (ansatz) of fluid flow dependence on pore size, while the numerical coefficients have been derived from the fitting of computer simulation data. The formulae obtained take into consideration such nanoflow features as adsorption of fluid on the pore walls and high slip velocity, which are usually neglected in petrophysical simulators operating with continuum fluid approach. These analytical formulae can be then incorporated into various larger scale models used for calculation of fluid flow in nanoporous media. This study is aiming the investigation of general phenomena occurring near the fluid–wall interfaces at nanoscale.