The sensitivity of filtered two fluid models to the underlying resolved simulation setup

Conference Dates

May 22-27, 2016


Eulerian-Eulerian modelling based on the Kinetic Theory of Granular Flow has proven to be a promising tool for investigating the hydrodynamic and reactive behaviour inside fluidized beds. The primary limitation of this approach is the very fine grid size necessary to fully resolve the transient solid structures that are typical of fluidized bed reactors. It therefore remains impractical to simulate industrial scale fluidized bed reactors using resolved Two Fluid Model (TFM) simulations. For this reason, there is currently widespread interest in developing sub-grid (filtered) models that allow accurate simulations at coarser grids by correcting for the effects of unresolved solid structures. However, little attention has been paid to the importance of the choice of the underlying TFM closures during the derivation of the filtered models.

This paper follows a similar approach to an establish filtered TFM (1) to derive sub-grid closures for the interphase momentum exchange , solids viscosity and solids pressure in 2D periodic simulations. These corrections are obtained for different particle-particle restitution coefficients, frictional pressure models and drag models as a function of the particle phase volume fraction and the filter size. This reveals at which values of the markers the individual resolved TFM model choices have significant effects on the final expressions derived for filtered TFMs. Based on these findings suggestions are made regarding the derivation of new filtered TFMs and the use of the existing models.

1. Y. Igci and S. Sundaresan. Constitutive Models for Filtered Two-Fluid Models of Fluidized Gas–Particle Flows. Ind. Eng. Chem. Res., 50: 13190-13201, 2013.

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