Axial
dispersion in alveolated channels was studied experimentally. Our motivation was to improve understanding of the physics of gas mixing in the pulmonary acinus. The apparatus consisted of a quasi-two-dimensional central convective channel surrounded top and bottom by dead-end cells (alveoli). Quasi-steady oscillatory bulk flow and a small steady-flow of tracer gas (He, SF,) were introduced upstream of the apparatus. The steady-state axial concentration distribution was measured by mass spectrometry, and its gradient was used to calculate an axial dispersion coefficient (0') from a generalized Fick's law. We found that for small Peclet (Pe) numbers D+ was appreciably smaller than molecular diffusivity of the tracer gas, while for large Pe, D* was substantially greater than the Taylor-Aris result for flow enhanced dispersion in non-alveolated parallel plates. I)* was sensitive to the ratio of alveolar volume to central channel volume, which was varied from 0.75 to 4.64. These results are consistent with theoretical predictions. We conclude that the structure of the alveolated channel alters the interaction between lateral diffusion and axial convection, and as a result, conditions axial dispersion phenomena.