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ISSN オンライン: 2642-0554

INFLUENCE OF A STRUCTURED WAVY SURFACE ON A TURBULENT FLOW

Shinji Nakagawa
Department of Chemical Engineering University of Illinois, Urbana, IL61801, USA

Thomas J. Hanratty
Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign Urbana, Illinois 61801, USA

要約

The influence of a train of sinusoidal waves on turbulent flow of water was studied. The waves had a height, α, of 0.5 mm and a wavelength, λ, of 5mm. The flow was such that a fully rough condition was realized. A consideration of the DNS study by Cherukat et al. (1998) of flow over a wavy wall with 2α/λ = 0.1 reveals that turbulence is sustained in a completely different way by a wavy wall than by a smooth wall. Experiments with LDV and PIV show some differences in the turbulence observed over smooth and wavy walls. However, the similarities are more striking. This is particularly evident in PIV measurements of the large scale flow structures associated with Reynolds shear stresses. These results support the notion that at a sufficient distance from the wall turbulent flows have universal structures, which depend only weakly on the structure of the wall.