An evaluation of non-local effects on the effective sub-grid behavior of fluidized gas-solid flows

Abstract

Large Scale Simulations (LSS) of fluidized gas-solid flows require sub-grid closures (meso-scale closures) to recover effects that are filtered by the coarse numerical grids that are applied. Sub-grid closure models based on results of highly resolved simulations with microscopic two-fluid modeling have been derived, assuming that local filtered parameters are independent of the flow topology. Recent results of highly resolved simulations of gas-solid suspensions, however, suggest that there are significant effects of the external flow over sub-grid filtered parameters (here called non-local effects). In this project it is proposed to study the impact of those effects over different filtered parameters, thereby establishing their relevance regarding future propositions of new sub-grid models. The studies will be developed departing from results of highly resolved simulations with microscopic two-fluid modeling. The simulations will be performed with the MFIX open code, for a particulate typical of catalytic cracking of petrol, under Reynolds numbers and domain average solid concentrations covering gas-solid flow topologies ranging from diluted rapid fluidized beds up to high density bubbling beds. (AU)