Merging molecular dynamics with homogenisation: a novel strategy for the modelling of nano-filtration phenomena

Abstract

Abstract Content of image described in text. Filtration flows through nanoporous membranes play a crucial role in a range of cutting-edge technologies, including water purification, osmotic power generation and targeted drug delivery. Molecular dynamics (MD) simulations are currently considered the state-of-the-art approach for modelling nano-filtration processes. However, their high computational cost makes simulating large-scale filtration systems impractical, limiting the ability to conduct extensive parametric studies and optimise design strategies. In the present paper, we merge a molecular analysis of the nano-filtration problem with a homogenisation technique, to upscale the filtration flow from the single nanopore description to the whole membrane scale phenomenon. The homogeneous model allows replacing the detailed description of the flow through the whole membrane with a simplified flow description, where the membrane is an effective smooth interface between two macroscopic fluid regions. The model rigorously quantifies jumps in the macroscopic solvent velocity and stresses across the homogeneous membrane via a set of tensorial quantities computed once and for all via MD simulations, enabling us to predictively quantify the membrane properties in the presence of nanoscopic pores. Finally, we validate the MD-homogenisation model by comparison with MD simulations of a water flow through arrays of pores, assessing the computational efficiency of the novel methodology.