Depth-limited oscillatory boundary layers on a rough bottom

Hitoshi Tanaka, Ahmad Sana, Ikuo Kawamura, Hiroto Yamaji

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5 Citations (Scopus)

Abstract

An experimental study is carried out to investigate the transformation of oscillatory boundary layer from ordinary to depth-limited one by using an oscillating tunnel with triangular roughness pasted on the top and bottom surfaces. The velocity is measured by one-component LDV. It is proved that only longer period of oscillation is not sufficient to induce depth-limited properties. Instead, the ratio of boundary layer thickness to the distance from the bottom to the free surface must be used in order to distinguish a depth-limited oscillatory boundary layer from an ordinary one. The experimental data for mean velocity, phase difference, fluctuating velocity, friction coefficient and boundary layer thickness are presented in order to elaborate the structure of depth-limited oscillatory boundary layers on a rough bottom. On the basis of the present experiments, a modification has been made in an existing criterion to distinguish between ordinary and depth-limited wave boundary layers. A typical field situation is discussed to show the usefulness of the proposed criterion.

Original languageEnglish
Pages (from-to)85-105
Number of pages21
JournalCoastal Engineering Journal
Volume41
Issue number1-4
Publication statusPublished - 1999

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Keywords

  • Bottom friction
  • Depth-limited oscillatory boundary layer
  • Friction coefficient
  • Long waves

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Ocean Engineering

Cite this

Tanaka, H., Sana, A., Kawamura, I., & Yamaji, H. (1999). Depth-limited oscillatory boundary layers on a rough bottom. Coastal Engineering Journal, 41(1-4), 85-105.