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Indoor transport of human expiratory droplets in association with airborne infectious disease transmission using a multiphase-flow approach.

机译：使用多相流方法与空气传播的传染病传播相关的人类呼气飞沫的室内运输。

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摘要

Human expiratory droplets can be pathogen carriers for various airborne infectious diseases. However, due to the discrete and polydispersive nature, investigations of their indoor transport characteristics have been challenged by various modeling and experimental difficulties. In this research, transport characteristics of expiratory droplets were investigated by treating the droplets or droplet nuclei as discrete matters. Motion tracks were modeled by a multiphase approach where the turbulent effects were treated by using stochastic methods. Experiments were performed in test chambers to obtain the turbulence characteristics of the bulk airflow using particle image velocimetry (PIV) techniques. The dispersions of polydispersed test droplets were measured in-situ by the Interferometric Mie imaging (IMI) method combined with light-scattering aerosol spectrometers. The applicability of the numerical model was tested by comparing the numerical data with the experimental results.;Results revealed the size-specific transport characteristics of expiratory droplets. Droplets or droplet nuclei with an initial size up to 45mum showed airborne transmittable behavior while those with initial sizes of 87.5mum or above settled quickly due to heavy gravitational effect. This is inconsistent with the current definition in infection control guidelines, in which airborne pathogen carriers are regarded as droplet nuclei of size 1-5mum. Smaller droplets and droplet nuclei were more favorable for lateral dispersions as characterized by the overall dispersion coefficient. The ventilation flow pattern also showed significant effects on the dispersion of expiratory droplet nuclei. The bulk airflow was the major driving mechanism for lateral dispersions, which was about an order of magnitude stronger than that by turbulent dispersion. The vertical settling time was a limiting factor for the final dispersion distances. The exhaust air vent significantly enhanced lateral dispersion towards its direction, indicating the needs for careful design of air vent locations. This study demonstrated the applicability of the current methodology without employing the perfectly mixed assumption and continuous phase surrogates.
机译：人的呼气飞沫可能是各种空气传播传染病的病原体携带者。然而，由于离散和多分散的性质，对其室内运输特性的研究受到各种建模和实验困难的挑战。在这项研究中，通过将飞沫或飞沫核视为离散物质来研究呼气飞沫的传输特性。运动轨迹是通过多阶段方法建模的，其中使用随机方法处理湍流效应。使用粒子图像测速（PIV）技术在测试室中进行了实验，以获得大气流的湍流特性。通过干涉米氏成像（IMI）方法结合光散射气溶胶光谱仪，对多分散测试液滴的分散度进行原位测量。通过将数值数据与实验结果进行比较，验证了数值模型的适用性。结果表明，呼气液滴的尺寸比传输特性。初始大小不超过45μm的液滴或液滴核表现出空气传播的行为，而初始大小不超过87.5mum的液滴或液滴核由于引力高而迅速沉降。这与感染控制指南中的当前定义不一致，在该指南中，空气传播的病原体携带者被视为大小为1-5μm的液滴核。以总分散系数为特征，较小的液滴和液滴核更有利于横向分散。通风流型还显示了对呼气液滴核扩散的显着影响。大量气流是横向分散的主要驱动机制，它比湍流分散强大约一个数量级。垂直沉降时间是最终分散距离的限制因素。排气孔显着增强了其方向上的横向扩散，表明需要仔细设计排气孔的位置。这项研究证明了当前方法的适用性，而没有采用完全混合的假设和连续相替代物。

著录项

  • 作者

    Wan, Man Pun.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 147 p.
  • 总页数 147
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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