Cartesian grid simulations of gas–solids flow systems with complex geometry

Complex geometries encountered in many applications of gas–solids flow need special treatment in most legacy multiphase flow solvers with Cartesian numerical grid. This paper briefly outlines the implementation of a cut cell technique in the open-source multiphase flow solver—MFIX for accurate representation of complex geometries. Specifically, applications of the Cartesian cut cell method to different gas–solids fluidization systems including a small scale bubbling fluidized bed with submerged tube bundle and a complete pilot-scale circulating fluidized bed will be presented. In addition to qualitative predictions on the general flow behaviors inside each system, quantitative comparison with the available experimental data will be presented. Furthermore, some results on extending the current cut-cell technique to Lagrangian–Eulerian simulations will be presented.

The Cartesian cut-cell technique allows representing complex geometry in the multiphase flow solver MFIX. A full-loop simulation of a Circulating Fluidized Bed, including the riser, cyclone and standpipe was conducted to illustrate this capability. Void fraction distribution in the unit is shown. Results show fairly good agreement with experimental data.Figure optionsDownload as PowerPoint slideHighlights
► Applications of the Cartesian cut-cell method to different gas–solids systems were presented.
► Bubble characteristics in a bubbling fluidized bed were accurately predicted.
► Large scale Circulating Fluidized Bed simulations were performed.