Numerical Analysis of Axial Dispersion in an Intermittent Oscillatory Flow.

Abstract

Ventilation by high-frequency oscillation (HFO) has gained widespread attention in clinical medicine because of its potential benefits to respiratory insufficiency. The axial dispersion in oscillatory flow is one of the important factors influencing gas transport during HFO. In this study, the gas transport in sinusoidally oscillatory and intermittent laminar flow in a straight circular pipe was numerically simulated to reveal the mechanism of dispersion. The diffusion of substance was simulated according to the random walk technique and its diffusive nature was evaluated by tracking the path of marked particles. The presence of a stationary period enhances the axial gas transport in the oscillatory flow, and the maximum ratio of effective diffusivity to the molecular diffusivity is twice that of sinusoidal oscillatory flow.