@article{oai:nagoya.repo.nii.ac.jp:00030657, author = {Nakamura, Ikuo and Sakai, Yasuhiko and Tsunoda, Hiroyuki and Liu, Shengjian}, issue = {2}, journal = {Memoirs of the School of Engineering, Nagoya University}, month = {Mar}, note = {In this research, we investigated the influences of the distortion of the flow generated by a sphere on the behaviors of velocity turbulence and plume diffusion. The incident turbulent flow was created by a biplainer square grid, so that the turbulence intensity decays downstream but the velocity field can be recognized roughly isotropic in the upstream region of the sphere. The diffusion field is an axisymmetric point-source plume which develops in this decaying grid turbulence and runs against the sphere frontally. Before giving the concrete experimental results and discussions, a general explanation on the effect of an obstacle on the turbulent diffusion is provided and the scientific significance of this research is clarified. In the second chapter, after an account of experimental instruments, the details of the conventional statistics of velocity and concentration field are provided. Special concerns are given to the variations of the velocity and concentration fluctuation intensity near the stagnation point. It is shown that the balance equations of velocity and concentration fluctuation intensity are very useful to understand these phenomena. In the third chapter, discussed are mainly the radial distributions of conventional and conditional statistics of concentration field around the sphere and the variation of the concentration detecting frequency along the stagnation line. The data are summarized by imaging a striation structure of a diffusing plume. The final chapter gives a detailed examination of the fractal feature of sets of iso concentration points taken from data on the stagnation line.}, pages = {135--184}, title = {Diffusion of turbulent plume around a sphere}, volume = {45}, year = {1994} }