A Nonbody Fitted Cut-Cell Meshing Strategy with Locally Refined Hexahedral Mesh for Particle-Resolved Computational Fluid Dynamics Study

Particle-resolved computational fluid dynamics (PRCFD) is an extensively utilized method for investigating fixed bed reactors. However, commonly used tetrahedral cells for discretizing complex pore structures may suffer from high cell counts and excessive mesh skewness near contact points. Therefore, a cut-cell meshing strategy based on locally refined hexahedral mesh has been proposed for the finite volume method (FVM) in this work. Specifically, spherical particles arranged in simple cubic, body-centered cubic, and face-centered cubic patterns were computationally studied with the realizable k-ε model and enhanced wall treatment (EWT) settings. Results demonstrate that the hexahedral meshes exhibited better accuracy in comparison to that of the tetrahedral meshes with respect to forced convective heat transfer. Compared to the tetrahedral meshes, the hexahedral meshes on average reduce cell counts by 85%, convergence iterations by 67%, and computational times by 95%. In addition, the hexahedral mesh remains advantageous over the tetrahedral mesh, even if the particle numbers increase within the packed bed. By significantly conserving computational resources while ensuring simulation accuracy, the hexahedral cut-cell meshing strategy makes it much more feasible to investigate packed beds with many thousands of particles. The CFD simulation with the proposed meshing strategy would be helpful in guiding the optimized design and operation of fixed bed reactors.