Abstract
Thus far, many wind tunnel experiments have been conducted in order to study the characteristics of atmospheric dispersion inside obstacles wakes in cases of accidental release of hazardous gas from industrial facilities. However, this paper considers the problem by focusing on the situation of the release point of thehazardous gas. In this study, we assume the pollution source to be located at a distance from various types of obstacles. Wind tunnel experiments were conducted to investigate the characteristics of mean and fluctuating concentrations around a normal plate. A tracer gas was emitted from a source located at a distance of twice the plate height upstream from the plate. The characteristics of plume entrainment into the wake region of the plate were clarified by examining its relation with flow patterns and turbulence structures. In addition, we focused on the characteristics of various kinds of peak-to-r. m. s. concentrations defined as values which were not exceeded for 90, 95, 99% of the cumulative probability density function of the concentration fluctuation. Based on the results, it was found that the concentration ratio at maximum 10% values could be estimated by the exponential probability distribution functions of the concentration fluctuation, independently of the concentration fluctuation intensity.
