dispersion

The redispersion factor of microbe-carrying particles, which is the ratio of the concentration of floor-derived microbes in room air to those on a floor surface, was determined, as was the percentage of floor-derived microbes in room air. These relationships were shown to vary according to conditions in the room. Equations were derived that allow these relationships to be calculated for a variety of room conditions, including air supply rates, levels of personnel activity, and the effect of gravitational deposition on microbe-carrying particles.

The prediction of plume dispersion near buildings is very important for the design of exhaust stacks andair intakes in order to avoid adverse air quality impacts. However, it is difficult to predict pollutantdispersion with certain accuracy due to the complex interaction between atmospheric flow and flowaround buildings.

The increasing incidence of airborne transmitted diseases indoors has prompted the attention ofstudying expiratory droplet dispersion and transport in built environments. Droplet dispersion in aroom under the conventional well-mixed and displacement ventilation is simulated. In this work, asource (i.e. a patient) and a receptor (i.e the susceptible object) were located in a mechanicalventilated room. This study evaluated droplet dispersion and mixing under well-mixing anddisplacement ventilation scheme.

Although unanimously acknowledged by the experts for its performances as regards energyeffectiveness and indoor air quality optimisation, humidity sensitive ventilation still too often suffersfrom a lack of knowledge inherent in its singularities. The matter of this article is thus to bring a newlighting on the humidity sensitive ventilation determining airflow rates in the calculations of ductworksdimensioning and in the energy impact related to the air renewal.

The paper describes small scale wind tunnel experiments on the dispersion of contaminants discharged from the bottom of courtyards and other enclosed spaces. The experiments covered a range of courtyards with ratios of depth to width from 5- (consistent with light wells and other very deep cavities) down to 0.1 (consistent with shallow enclosed squares and piazzas that are frequently found in the urban environment).