Transport Mechanism of Airborne Particulate Matter Transport in Ventilated Multi-room Environment
Date Issued
2005
Date
2005
Author(s)
Hu, Ting-Shing
DOI
zh-TW
Abstract
The main purpose of this research is to investigate the mechanism of airborne particulate matter transport in ventilated multi-room environment from a Lagrangian particle trajectory tracking technique. The flow field is simulated by using the k-ε turbulence model. We not only add the drag force and the gravitational force into the Lagrangian particle tracking model, but also consider the Brownian motion effect and Saffman lift force. Our study first analyzes how the numbers of particle released affect the mass and count concentrations. The numerical model is next verified by the reliable experimental measurement of Lu et al. (1996). The particle mass concentration are in good agreement with the experimental data.
Our study includes six scenarios for the particle diameters of 10μm, 5μm, 2.5μm, 1μm, 0.5μm, 0.1μm and 0.05μm to investigate the transport mechanism of airborne particulate matter. For each particle diameter, we apply the drag force, gravitational force, Brownian motion and Saffman lift force in simulating airborne particle transport. The numerical results show that the smaller particle diameter is, the little influence of the drag force is. When particle diameter reaches 0.1μm, the influence of the drag force approach to zero. The Saffman lift force is significantly important to particle trajectory for the particle diameter ranging from 5μm to 2.5μm, and the Saffman lift force is the most important mechanism to the particle diameter of 5μm. Furthermore, the Brownian motion has no effect on particle trajectory for the particle diameter greater than 1μm. And the particle trajectory simulation must take account of the Brownian motion effect for the particle diameter smaller than 0.5μm.
Subjects
計算流體力學
氣懸微粒軌跡追蹤模式
k-ε紊流模式
computational fluid dynamic
Lagrangian particle trajectory tracking technique
k-ε turbulence model
mechanisms of airborne particulate
Type
thesis