| Budget Amount *help |
¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
Fiscal Year 2013: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2012: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2011: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Outline of Final Research Achievements |
Using direct numerical simulation(DNS) of turbulence in a periodic box with a maximum of 4096^3 grid points and Taylor micro-scale Reynolds numbers Rλ up to 1131, it is shown that there is a transition in the forms of the significant vortical structures, from isolated vortices (when Rλ is less than 100) to complex thin-shear layers (when Rλ exceeds about 1000). Within the significant layers, strong vortices are generated with micro-scale thickness 10η (η is the Kolmogorov micro scale). The interfaces of the layers act partly as a barrier to the fluctuations outside the layer.
We also performed the DNS of turbulent boundary layers (TBL) along a flat plate to study the properties of turbulent/non-turbulent (T/NT) interface of the TBL. Analysis of the conditional statistics near the interface shows that conditional cross correlations of the streamwise or the wall-normal velocity change sharply across the interface. This is consistent with the blocking mechanism of the interface.
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