| 講演要旨： |
The dispersion of small particles in turbulent boundary layers is crucial in a number of industrial and environmental applications. In most applications, the non-trivial key information is particle spatial distribution which is required to size and quantify the deposition/reaction/absorption processes. In the boundary layer case, it is known that particles tend to migrate towards the wall (Reeks, 1983), and it is also known (e.g. Wang and Maxey, 1993) that particles distribute preferentially avoiding strong vortical regions and segregating into straining regions.
In this talk, theoretical and experimental evidence is reviewed which shows that fluid motions in turbulent boundary layers are intermittent and have a strongly organized and coherent nature represented by the large scale motions. These motions, even though not exactly repeatable and only quasi-deterministic, control the transport of the dispersed species in such a way that the overall distribution will resemble not at all those given by methods in which these motions are ignored. During this talk, the current framework models for the structures turbulent boundary layers will be discussed in connection with the time and space local mechanisms by which transfer of inertial particles takes place. Local and global indicators of the flow properties influencing particle preferential distribution will also be addressed in connection with different criteria to measure particle preferential accumulation/segregation. Implications for subgrid modelling will also be addressed.
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