Pathway analogy for computational fluid dynamics simulations of fluid flow through structured packed beds

Predicting pressure drop in structured packed beds is critical for the design of industrial chemical reactors and heat exchangers. While particle-resolved Computational Fluid Dynamics (CFD) offers high fidelity, its prohibitive computational cost for large-scale systems necessitates efficient modeling strategies. This study introduces a novel pathway analogy for fluid flow through structured packed beds in a simple cubic arrangement. The approach deconstructs the complex interstitial flow field into a finite set of discrete, hydraulically independent pathways—classified as full, half, or quarter based on their proximity to the container walls. High-fidelity CFD simulations confirm that cross-flow between these pathways is negligible ( < 1%) both in laminar and turbulent regimes, justifying their treatment as independent flow units. Universal correlations for the friction factor and a normalized pressure drop are derived for each pathway type as a function of Reynolds number, demonstrating negligible dependence on particle diameter. These foundational correlations are synthesized into a mechanistic engineering model that reconstructs the total pressure drop for a bed of any dimension by summing the weighted contributions of all individual pathways. The model is rigorously validated against experimental data from the literature, showing strong agreement across a wide range of Reynolds numbers and bed configurations. This pathway analogy provides a robust, physics-based framework for drastic computational domain reduction, offering a valuable tool for the efficient design and scaling of structured packed bed systems.