Dispersion Processes in Environmental Flows
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Environmental flows give significant effects on our daily life in many ways. It is so particularly if one considers turbulent dispersion of scalar quantities, such as heat and various chemical species in the atmosphere and the water systems. For example, "Heat Island" phenomena, which arise from the excess heat deposition in the urban atmosphere, are commonly observed in many large cities around the world. In the COE project, dusts and chemical species transport processes originating in the Asian continent are one of the primary targets of investigation. Regarding the contribution to the project, my interest lies in the dust deposition processes within the local atmosphere, smaller than geostrophic scale, and the study will be extended to other turbulent dispersion processes of scalar quantities in the small scale atmosphere and water environmental systems.
There are three different ongoing studies, ranging from water in the ground to atmospheric transport processes, namely 1) development of groundwater velocimeter using a single borehole, 2) study on meso-scale atmospheric motion and dust fall mechanisms, 3) investigation of turbulent structures in the wake of trees. The third one is important, since it is responsible for improving city air quality as well as urban temperature environment. Fig.1 and 2 indicate temperature and flow patterns for mixed convection about the heated vertical cylinder in a water-saturated porous medium, in connection with the groundwater velocimeter development.
Fig.1 Temperature field in a horizontal plane
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Fig.2 Streak lines in mixed convection
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