Numerical simulation of turbulent gas–solid flow using an approximate deconvolution model

Abstract

In our prior study (Schneiderbauer and Saeedipour, Phys. Fluids, 2018; 30:023301), an a-priori analysis on the spatially-filtered two-fluid model (TFM) was presented for turbulent gas–solid flows, where the unresolved terms were modeled by an approximate deconvolution model (ADM). With such an approach, an approximation of the unfiltered solution is obtained by repeated filtering allowing the determination of the RSFS (resolved sub-filter scales) contribution of unclosed terms of the filtered equations directly. In the present study, this ADM-TFM approach is implemented in an a-posteriori manner for the coarse grid simulation of a fluidized bed of Geldart type B particles and is verified against highly-resolved TFM simulations. Furthermore, different regularization methods, which account for the sub-filter scale (SFS) contribution, are presented and discussed with respect to their predictiveness and stability. It is shown that employing an appropriate rheological model for the solid phase considerably improves stability without removing too much energy from the resolved scales. Finally, the ADM-TFM predictions are in fairly good agreement with the fine grid reference case and do not show a notable grid-dependency. Compared to TFM simulations using the same grid resolution, the ADM-TFM approach does only require marginally more computational resources.