Experiments have been carried out to investigate the scalar field to be formed around circular cylinder by ejecting nozzle fluid from the 2-D plane nozzle. $CO_2$ and air were used as the nozzle fluids with the parameters H(width of nozzle), D(cylinder diameter), L(distance from nozzle to cylinder) and $U_j$(exit velocity)
In order to elucidate the mixing characteristics, measurements of concentration distribution of $CO_2$ and flow visualization using the $TiCl_4$ technique were conducted for the combined various parameters.
From the experimental observation, jet growth rate, separation point and $CO_2$ concentration were mainly dependent on the dimensionless parameters L/H. D/H for the fixed Reynolds number. It is expected that Coanda effect would be important to predict the scalar field.
