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 installed in a flat-plate turbulent boundary layer. The mean concentration distributions around the hill model were measured by a homemade flame ionization detector (FID), and the effects of flow characteristics of the incoming boundary-layer on the concentration field are discussed. Depending on the boundary layer thickness just upstream of the hill model, a maximum-value location of the mean concentration distribution in the downstream region of the model moves vertically with respect to the dividing streamline of the separation bubble, and the spanwise distribution becomes wider as the boundary-layer thickness is thinner than the hill height.
