This project is both multi-scale and multi-disciplinary, and spans research areas across physics, mechanical engineering, computer science and chemical engineering. Our aim is to produce, for the first time, a general, robust and efficient open-source code for the simulation of non-continuum flows for engineering applications. Such flows are vital to the performance of a number of potentially transformative future technologies (e.g., highly-efficient sea-water desalination using membranes of carbon nanotubes, and nano-structured hydrophobic surfaces for marine drag reduction) but they cannot be simulated using conventional continuum-fluid simulations. Our work exploits the core methodological advances emerging from the EPSRC Programme Grant "Non-equilibrium Fluid Dynamics for Micro/Nano Engineering Systems" (EP/I011927/1), which have demonstrated exciting potential in the multi-scale modelling of non-continuum flows using hybrid continuum-particle methods. The software developed in this project builds on the already widely-adopted open-source code OpenFOAM for computational fluid dynamics. In capitalising on a) the success of the UK's OpenFOAM software and b) the EPSRC's Programme Grant investment in a strategic research area, this project aims to bring sustainability to both.