CFD Analysis about Influence of Human Movements on Diffusion of Indoor Air Pollutants

Abstract

It has been proved that human movement plays an important role in diffusion of indoor air pollutants. A typical place of an example is the reception in hospital. This place is crowded with walking patients, doctors, and virus may be diffused. Therefore it is essential to know how human movements affect the indoor air pollutants, so that we can control the diffusion of pollutants. The main aim of our research is to evaluate the influence quantitatively with Scale for Ventilation Efficiency 2 (SVE2), which indicates the second moment of space distribution of concentration. By means of SVE2, we can evaluate the effectiveness of ventilation system. In the near future, this method would be helpful to develop better systems to deal with dynamic conditions such as human movements. As a method, we used CFD simulation to study the influence for pollutant diffusion by ventilation or human movement. First, we did a validation for the software by referring the experiment carried out by Kondo. Next, we simulated two situations including a room with ventilation, and the same room with a person doing the circular movement. The pollutants diffusion of these two situations are compared to study the influence caused by ventilation or movements. We calculated SVE2 for both situations to evaluate the influence quantitatively. The results of validation work show that in totally 6 test points, CFD results for air velocity of 4 points fit well with the experiment results. Calculation results of SVE2 show that the influence of human movements are more significant than the influence of ventilation with the same input power. It is also confirmed for the influence of movements with different types of human models, the less input power, the less influence on diffusion of pollutants. We conclude that firstly CFD method is proved to be validated. Secondly SVE2 is a proper scale to evaluate the diffusion effect of human movements or ventilations. Further study is to be carried out to continue using the scales to evaluate how ventilation systems restrain the diffusion of pollutants.