Numerical investigation of nanofluid natural convection coupling with nanoparticles sedimentation

This paper aims to investigate the relationships between nanofluid natural convection and nanoparticles sedimentation through open source computational fluid dynamics (CFD) simulations. Three new OpenFOAM solvers are developed based on different approaches in both single- and multi-phase ways. Considering 0.64% Al2O3/water nanofluid in a two-dimensional square cavity, nanoparticles sedimentation is believed to have considerable impact on nanofluid natural convection when Rayleigh number is in the range of Ra=106∼107. With a sedimentation layer of nanoparticles at cavity bottom, average Nusselt number along heating wall is found to be lower than that in the corresponding case simulated via single-phase approach. Furthermore, the impact of nanofluid natural convection on nanoparticles sedimentation is found to be increasingly remarkable when Rayleigh number is increased. In the present work, pure water is found to have slightly greater average Nusselt number than 0.64% Al2O3/water nanofluid. It is also recommended that temperature-dependent variations of nanofluid properties are not recommended to be updated at each time step in CFD simulations in terms of reducing computational effort.