Modelling approaches for micro- and nanoscale diffusion phenomena

摘要

In this paper the current state-of-the-art approaches for modelling diffusion transport in micro and nanofluidic devices are reviewed. While convective transport plays a dominant role for most macroscale devices, the importance of diffusive transport phenomena increases as the characteristic dimensions of the system shrink to smaller scales. Identification of the suitable modelling approach depends on the characteristic time and length scales of the investigated problem as well as on number densities and molecular properties of the substance considered. Furthermore, most applications in nanotechnology are characterised by their inherent multiscale nature. In micro and nanofluidic devices, continuum models cannot fully capture the physics of the phenomena involved in particular areas. Consequently, the main modelling challenge for such devices is associated with multiple scales and transient regions exhibiting both continuum and molecular behaviour. Hybrid continuum-molecular and meta-modelling techniques are capable of describing this multiscale behaviour; however there are still open questions related to efficiency and applicability of the aforementioned techniques. In this paper an overview of the micro and nanoscale approaches for modelling diffusion transport is presented, including classical continuum level description, molecular dynamics, meta-scale models and hybrid multiscale techniques, with the focus on the transport of macromolecules.