Characterizing the turbulent drag properties of rough surfaces with a Taylor–Couette set-up
نویسندگان
چکیده
Wall-roughness induces extra drag in wall-bounded turbulent flows. Mapping any given roughness geometry to its fluid dynamic behaviour has been hampered by the lack of accurate and direct measurements skin-friction drag. Here Taylor-Couette (TC) system provides an opportunity as it is a closed allows directly reliably measure skin-friction. However, wall-curvature potentially complicates connection between wall friction characteristics. we investigate effects hydrodynamically fully rough surface on highly turbulent, inner cylinder rotating, TC flow. We find that turbulence, where height k three orders magnitude smaller than Obukhov curvature length Lc (which characterizes flow, see Berghout et al. arXiv: 2003.03294, 2020), are similar those flat plate boundary layer (BL). Hence, value equivalent sand grain ks, properties surface, found for comparable sandpaper surfaces BL. Next, obtain dependence torque (skin-friction drag) Reynolds number roughness, characterized agreement with experimental results within 5 percent. Our findings demonstrate global facility well suited deduce surface.
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ژورنال
عنوان ژورنال: Journal of Fluid Mechanics
سال: 2021
ISSN: ['0022-1120', '1469-7645']
DOI: https://doi.org/10.1017/jfm.2021.413