A scale sensitive filtered sub-grid drag model for fluidized gas-particle flows

Abstract

A new sub-grid drag model is proposed for fluidized gas-particle flows which stands among those derived from filtering over results of meso-scale highly resolved simulations with microscopic two-fluid modeling. Filtered sub-grid models frequently correlate to meso-scale effects alone, taking no account of any micro-scale or macro-scale effects, a clear drawback in view of the lack of scale separation characteristic of gas-particle fluidized flows. The currently proposed sub-grid drag model accounts for the micro-scale effect through a range of particle Froude numbers, while the macro-scale effect is accounted for in average, by considering ranges of average solid volume fractions and gas flow Reynolds numbers. For the sake of comparing the current model to similar models, we use the expression “accounting” to mean the background of consideration of micro and macro-scale aspects that are accounted for in the models. In this particular sense, the proposed model represents a gain over previous versions.