  This study presents a novel method for the calculation of void fractions in
the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) simulations
known as the Gaussian Integral Method (GIM). GIM demonstrates versatility
across different types of grids including structured and unstructured
polyhedral meshes without the need for any treatment at the boundaries. An
optimization method is developed for making GIM grid-independent from
resolution and type. The method is validated against experimental data of a
fluidized bed. The validation results demonstrate realistic results which
resemble experimental data. Furthermore, unstructured polyhedral grids
outperformed structured grids of equivalent resolution providing results more
aligned with experimental data. The gradient of the void fraction is solved in
the CFD solver and is used in the DEM solver for precise estimation of the void
fraction at a particle location. In conclusion, GIM provides a solution for
void fraction calculations in particulate media simulations with complex
geometries applicable to industrial needs.
