Self-preservation of a Turbulent Boundary Layer over d-type Roughness

• MOCHIZUKI Shinsuke

  Department of Mechanical Engineering, Yamaguchi University

• KAMEDA Takatsugu

  Department of Mechanical Engineering, Yamaguchi University

• OSAKA Hideo

  Department of Mechanical Engineering, Yamaguchi University

Abstract

Using a direct drag balance measurement for the local wall shear stress, self-preserving development of a turbulent boundary layer was achieved experimentally over a d-type rough surface without pressure gradients. The wall shear stress and mean velocity measurements confirmed the requirements for exact self-similarity and highly similar Reynolds stress profiles within the Reynolds number range for a constant skin friction coefficient. Under the condition that the boundary layer flow is completely independent of Reynolds number, the effect of wall roughness was investigated with respect to the similarity laws for the wall layer as well as the outer layer. Experimental observation reveals the wall similarity ∂U/∂y = u_τ/ky to be applicable to the present rough wall boundary layer remaining the accepted value of Kármán constant to be κ= 0.41. Otherwise, investigation of the wake strength in the mean velocity and Reynolds stress profiles reveals that the wall roughness does affect the outer layer structure. Reynolds stress measurements indicate that the primary effect of wall roughness on turbulence properties is in the component normal to the wall.

Journal

• Journal of Fluid Science and Technology

  Journal of Fluid Science and Technology 1 (1), 24-35, 2006

  The Japan Society of Mechanical Engineers

Keywords

• Turbulent Flow
• Boundary Layer
• Law of the Wall
• d-Type Roughness

Details

• CRID: 1390001205246707200
• NII Article ID: 130000077030
• DOI: 10.1299/jfst.1.24
• ISSN: 18805558
• Web Site: http://www.jstage.jst.go.jp/article/jfst/1/1/1_1_24/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed