Author(s): Hans J. Zippe; Walter H. Graf

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Abstract: Experimental researeli on flow over permeable surfaces is reported, in which flow over a permeable, rough surface is compared with flow over non-permeable, rough and smooth surfaces. The experiments were conducted in a wind tunnel using two permeable surfaces (Fig. 4) of relative thicknesses D/de = 2,73 and 9,67. Velocity profiles and their turbulent fluctuations (Fig. 2, Fig. 5 and Fig. 8) were measured with a constant-temperature hotfilm-anemometer. The universal velocity-defect law, eq. 2, was applied to obtain the shear velocity, u*.; and the law of the wall, eq. 1, was used to obtain the reference level (Fig. 3) and the roughness height, y', (Fig. 6); the impulse equation was used to check these results. The local resistance coefficient, e'f, versus the Reynolds number, Re, given in Fig. 7, may be considered as the resulting display of data. It is concluded that the boundary resistance of the tested permeable surface is higher than that of the non-permeable boundaries having identical roughness.

DOI: https://doi.org/10.1080/00221688309499450

Year: 1983