The sensitivity of filtered Two Fluid Models to the underlying resolved simulation setup

The filtered two fluid model (fTFM) is a promising approach for enabling large scale fluidized bed reactor simulations using multiphase flow modelling. A substantial amount of research has been conducted in this field to derive filtered closures for all applicable transport processes including drag, stresses, heat transfer, scalar transport and reactions. This work aims to investigate the effect of TFM closures used in the resolved simulations from which fTFM closures are derived in order to assess the degree of uncertainty stemming from this source. In addition, the filtering approach provides a good platform for building a detailed understanding of the effects of different TFM closures. Simulations showed that the drag model used in the resolved simulations had the most significant effect on the filtered quantities derived. Inclusion of a frictional pressure model also had a large influence in the dense regions of the domain. Selection of a more generic drag model and inclusion of a frictional pressure model is therefore recommended for future studies. Finally, results revealed that the effects of TFM closures on filtered quantities could be grouped into two categories: interphase transport (drag, heat transfer and reactions) and diffusive transport (stresses and scalar transport). This suggests a common methodology in terms of filtered model form for these two groups.