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The effect of riblet wall on the two-phase turbulent boundary layer containing 355 μm polystyrene particles was investigated by using particle image velocimetry (PIV). The effects of riblet wall on the characteristics of two-phase turbulent boundary layer were analyzed by comparing the average velocity profile, turbulence and Reynolds shear stress of the flow over the riblet and smooth surface. The spatial multi-scale local average structure function and λci vorticity identification criterion of hairpin vortex head (clockwise spanwise vortex) were used together to accurately identify the vortex center and extract the spatial topology of the surrounding fluctuating velocity and streamline. The numerical law of the forward vortices at different wall-normal heights was calculated. The results show that, compared with the smooth surface, the buffer layer of the average velocity profile of the riblet wall rises partly, the logarithmic region shifts outward, and the friction velocity and frictional shear stress of the riblet wall decrease, resluting in a drag reduction of 4.86%. At the same normal height, compared with the smooth wall, the clockwise vortexes detected on the riblet wall have smaller dip angles and fewer numbers, and the streamwise fluctuating velocity around the riblet wall is weak, showing that in two-phase flow, the riblet wall can weaken the intensity and finally decreases the drag.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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