Abstract
Detailed transport mechanism of concentration fluctuation was investigated by wind tunnel experiment results. A simplified condition of an urban area was recreated by square shaped obstacles in the test area of tunnel. The space pinched by separated obstacles in the center of the block alignment was set as the measurement area. Inflow angle was tilted in a minute (5 and 25) degrees. Tracer gas was ejected from the point. Spatial distribution of the correlation term between the velocity and the concentration were measured in each case. Distributions of mean velocity field, turbulent kinetic energy, mean concentration, variance of concentration, skewness and each direction's turbulent concentration flux were shown in each inflow angle. The budget of each terms in the transport equation of the variance of concentration was calculated in a discretized manner. The results of them in a several inflow condition were compared and the difference of the mechanism of the transport was noted by referring the component which plays an important part of their properties.
