Diffusive and dispersive processes in the aquatic environment and the modeling methods

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The research study conducted is concerned with diffusive and dispersive processes of various kinds of natural water environment. Through discussion meetingseach study by the participating investigators was compared and the overall view on the diffusive and dispersive processes has been presented. The research results obtained by each investigator are summarized as follows : l. The turbulent wall plume was analyzed with the aid of the k - epsilon turbulence model and the turbulent diffusivity of this flow was obtained. 2. The vertical turbulent diffusivity of the enclosed body of water such as a bay or a lake was formulated and the result was verified. 3. Diffusion and dispersion of turbid matter in a reservoir was studied by both physical and mathematical models. 4. The turbulent diffusivity and dispersion coefficient of composite open channel flow were formulated and verified experimentally. 5. A computer program of simulating the movement of suspended material in the sea was develope … More d to study the relative importance of the diffusive and advective transport. Also, two dimensional FEM and three dimensional FDM simulation programs of the diffusion in the sea were developed. 6. A new scheme of finite difference of the advective terms was developed to give the very high accuracy. Also, a new formulation of the one dimensional dispersion coefficient of the bay was proposed and tested with a number of set of field data. 7. The one dimensional dispersion coefficient of rivers was studied on the basis of the Lagrangian formulation and large number of data collected. Also, a new calculation method of the two dimensional diffusion equation in rivers was formulated using the general natural coordinate system. 8. The turbulent diffusivity in the sea was analyzed using the field data obtained in Tokyo Bay. 9. A good estimate of the horizontal turbulent diffusivity of bays was presented collecting and analyzing the field data. Also, a method and its problem of attaining the similarity of turbulent diffusivity in the bay was presented. 10. A new method of changing the flow structure by modification of the topography of the straits was proposed and demonstrated using the hydraulic model. Less