Variation of the drag coefficient with the free-stream turbulence intensity: (●) smooth sphere, Achenbach (Ref. 11); (▲) , (2.1%), (×) (3.8%), Raithby and Eckert (Ref. 3); (◻) , (○) (4.5%), (▽) (6.0%), Torii et al. (Ref. 4).
Schematic of the experimental setup.
Variation of the FST intensity along the streamwise direction (; ): (○) grid 1, (◻) grid 2, and (△) grid 3. The experimental data are fitted using a power law (Refs. 19 and 20). Here, corresponds to the location of grid, and is the stagnation point of sphere.
Variation of the drag coefficient with the Reynolds number: (●) basic sphere, (○) , (◻) 6%, and (△) 8%. The data from Achenbach (Ref. 11) for basic sphere (×) are also included here.
Surface pressure distributions: (a) , (b) 6%, and (c) 8%.
Oil-flow patterns on the sphere surface at : (a) , (b) 6%, and (c) 8%. The broken arrows indicate the approximate locations of laminar separation (LS), reattachment (RA), and turbulent separation (TS), respectively. Note that the main separation line is not clearly observable at low wind speed as for in (a).
Profiles of the mean streamwise velocity (●) and rms streamwise velocity fluctuations (○) above the sphere surface for : (a) , (b) , (c) , (d) , and (e) .
Characteristics of grids used in this study. Here, , Tu, and denote the grid solidity, turbulence intensity, and integral length scale, respectively. See Fig. 3 for the measurement locations of Tu and .
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