Numerical simulation can provide detailed understanding of mass transport within complex structures. For this purpose, numerical tools are required that can resolve the complex morphology and consider the contribution of both convection and diffusion. Solving the Navier–Stokes equations alone, however, neglects self-diffusion. This influences the simulated displacement distribution of flow especially in porous media at low Péclet numbers (Pe < 16) and in near-wall regions where diffusion is the dominant mechanism. To address this problem, this study uses μCT-based computational fluid dynamics (CFD) simulations in OpenFOAM coupled with the random-walk particle tracking (PT) module disTrackFoam and cross-validated experimentally using pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) measurements of gas flow within open-cell foams (OCFs). The results of the multi-scale simulations—with a resolution of 130–190 µm—and experimental PFG NMR data are compared in terms of diffusion propagators, which are microscopic displacement distributions of gas flows in OCFs during certain observation times. Four different flow rates with Péclet numbers in the range of 0.7–16 are studied in the laminar flow regime within 10 and 20 PPI OCFs, and axial dispersion coefficients were calculated. Cross-validation of PFG NMR measurements and CFD-PT simulations revealed a very good matching with integral differences below 0.04%, underpinning the capability of both complementary methods for multi-scale transport analysis.

数值模拟可以提供对复杂结构内质量传递的详细了解。为此，需要能够解析复杂形态并考虑对流和扩散的贡献的数值工具。然而，单独求解纳维-斯托克斯方程忽略了自扩散。这会影响流动的模拟位移分布，特别是在低佩克莱数 (Pe < 16) 的多孔介质中以及在扩散是主要机制的近壁区域中。为了解决这个问题，本研究在 OpenFOAM 中使用基于 μCT 的计算流体动力学 (CFD) 模拟，结合随机游走粒子跟踪 (PT) 模块disTrackFoam，并使用脉冲场梯度 (PFG) 核磁共振进行交叉验证实验。 NMR）测量开孔泡沫 (OCF) 内的气体流量。多尺度模拟的结果（分辨率为 130-190 µm）与实验 PFG NMR 数据在扩散传播器方面进行了比较，扩散传播器是 OCF 中气流在特定观测时间内的微观位移分布。在 10 和 20 PPI OCF 内的层流流态中研究了佩克莱数在 0.7-16 范围内的四种不同流速，并计算了轴向扩散系数。 PFG NMR 测量和 CFD-PT 模拟的交叉验证显示出非常好的匹配，积分差异低于 0.04%，支撑了两种互补方法进行多尺度输运分析的能力。