Implementation and testing of a new openfoam solver for pressure-driven liquid flows on the nanoscale

Over the past two decades, several researchers have presented experimental data from pressure-driven water flow through carbon nanotubes quoting mass flow rates which are four to five orders of magnitude higher than those predicted by the Navier–Stokes equations with no-slip condition. The current work examines the development of an OpenFOAM solver for creeping flows that better accounts for some micro- and nano-scale diffusion processes. It is based on the observation that a change of velocity variable within the classical Navier–Stokes equations leads to a form of flow model with additional diffusive terms which become apparent at the micro- and nano-scale. Numerical simulations from the new solver compare well with associated analytical solutions that match the experimental flow enhancement observed in cylindrical tubes. This lays the foundations for further investigations of liquid flows in more complex nano-sized geometries, such as those obtained from pore-scale imaging.