International Journal of Microscale and Nanoscale Thermal and Fluid Transport Phenomena vol:2 issue:2 pages:1-26
Multiphase flow in microchannels has gained much interest in recent years given the numerous emerging applications of microfluidics that promise to provide technological innovations not realizable with conventional channels. Moving forward, microfluidics is also envisioned to allow for process intensification of industrial scale processes, hence the production capacity is expected to span from nanoliters to cubic meters, from micrograms to tons. The successful design of microfluidic devices relies on the need to fully understand the flow dynamics and physics. While this has historically been achieved mainly by experimental means, more recently there has been a shift towards the conveniences offered by numerical modelling, in particular due to advances in the field of multiphase computational fluid dynamics (CFD) and the maturity of both proprietary codes and commercial software. This article reviews the state of the art of microfluidic multiphase flow simulation. Works utilizing a variety of computational techniques such as Volume-of-Fluid, Level-Set, Lattice Boltzmann Method, Phase-Field and Finite-Element Front-Tracking Method are described. Particular attention is given to the use of FLUENT CFD software, including detailed modelling procedures. The importance of 3D modelling is highlighted by the comparison of several works using 2D and 3D models and a discussion on the similarities between slug formation and jet instability break-up. Several applications of CFD to microfluidic flow are covered, including the study of formation and flow of gas slugs and liquid droplets in microchannels, the effect of wetting properties on two-phase flow and the simulation of nucleate boiling. Common modelling practices are consolidated and reviewed, and potential future development directions are identified.