(455c) Filtered Two-Fluid Models for Fluidized Gas-Particle Suspensions

Gas-particle flows exhibit large fluctuations in velocities and local suspension density. In riser flows, these fluctuations are associated with the random motion of the individual particles and with the chaotic motion of particle clusters, which are repeatedly formed and broken apart. These clusters occur over a wide range of length scales and their dynamics span a broad range of time scales. We construct filtered hydrodynamic models for such systems by averaging over fluctuations occurring on short length and time scales, and determine the associated constitutive models by filtering results obtained from highly resolved simulations of a kinetic theory based model for fluidized suspensions. In this presentation, we will describe results obtained by simulating such filtered hydrodynamic models and compare them against simulations of the kinetic theory model which formed the starting point of the filtering analysis. Such a verification study exposes conditions when the filtered model is able to afford grid-size independent solutions at much coarser resolutions than the original model and when the macroscale character predicted by the filtered and kinetic theory models are in agreement.