A LBM-FVM cross-scale coupling approach for the simulation of the atmospheric methane photocatalytic removal

A cross-scale LBM-FVM method (CLFM) is developed to model the methane photocatalytic removal. At the macroscopic level, the Finite Volume Method (FVM) is employed to simulate the flow, heat, and mass transfer fields, while the Lattice Boltzmann Method (LBM) is applied at the pore scale to capture detailed surface reactions on the catalyst units. A bridging strategy is introduced to ensure accurate and efficient data exchange between the two scales. Validation results demonstrated that CLFM reproduced velocity and temperature fields for two-dimensional channel and Poiseuille flows with high consistency compared with standalone FVM and LBM. Using a 2:1 coarse-to-fine grid ratio, the method maintained high accuracy while significantly improving computational efficiency. Among the 70 catalyst units examined, ordered distributions outperformed random and staggered distributions, with the pentagonal posts (D58) exhibiting the best overall performance. Specifically, D58 achieved a photocatalytic efficiency of 20.42%, a saving to investment ratio of 3.0, and a methane purification rate of 2.35 × 10−10 g/s. These findings demonstrate the capability of CLFM to combine accuracy and efficiency in multiphysics chemical simulations, offering a robust framework for catalyst optimization and performance enhancement in methane photocatalytic removal systems.