Abstract
We have investigated experimentally the turbulent diffusion processes of ethylene emitted from a point source in the upstream region of a two-dimensional hill model. By using the fast-response flame ionization detector (FFID), the mean and fluctuating concentration distributions are measured quantitatively. It is found that in the separated region, the mean concentration profiles are almost uniform in the vertical direction, and the locations of the maximum concentration appear along the dividing streamline formed in the downstream region of the hilltop. On the other hand, the r.m.s. values of concentration fluctuations become maximum at the outer edge of the concentration boundary layer, and become small in the separated region where the mean concentration keeps a high value.
