Handling contact points in reactive CFD simulations of heterogeneous catalytic fixed bed reactors

The mesh generation is a crucial step for Computational Fluid Dynamic (CFD) simulations and incorrect numerical descriptions of the geometry may strongly affect the reliability and the accuracy of the results. This is especially true in handling the contact points in random packed bed of spheres. In this respect, we provide a systematic investigation of the treatment of the contact points for reactive CFD simulations of gas-solid packed beds of spheres. In particular, building on previous literature results on radial heat transfer and pressure drop simulations, we extend and assess the bridge method to reaction at surfaces. At this scope, we first analyze a regular bed of spheres in laminar conditions (Re~80). This regular packed bed and the laminar flow regime allow for a direct and feasible meshing of the contact points, thus giving the possibility to perform explicit comparisons between meshes with and without bridges. In doing so, we identify guidelines that are then extended and tested to the meshing of a random packed bed reactor. In this way, we identify a meshing protocol, which can be adopted to properly describe surface reactivity in packed bed reactors along with a concomitant sound description of pressure drops and heat transfer.