| Budget Amount *help |
¥17,030,000 (Direct Cost: ¥13,100,000、Indirect Cost: ¥3,930,000)
Fiscal Year 2017: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2016: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Fiscal Year 2015: ¥12,350,000 (Direct Cost: ¥9,500,000、Indirect Cost: ¥2,850,000)
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| Outline of Final Research Achievements |
One of the most striking feature of rheological drag reduction phenomenon is the existence of a so-called maximum drag reduction (MDR) asymptote. In this study, we performed time-resolved and multi-camera PIV measurements for turbulent boundary layer at the high drag reduction ratio beyond 70 % and clarified turbulence statistics and the feature of very large-scale coherent structures observed in the MDR region. It was found that the streamwise maximum length scale was up to 2.5 times larger than the boundary layer thickness. Regarding the numerical approach, we proposed a new constitutive equation model for dilute surfactant aqueous solutions with shear-banding and evaluated its rheological properties. In addition, we clarified the elastic potential energy budget for the drag-reducing turbulent boundary layer flow.
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