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Response of the fully developed pipe flow to rough wall disturbances (mean velocity field)

Publication Date
  • Pipe Flow
  • Rough Wall
  • Response
  • Turbulent Structure
  • D-Type And K-Type Roughness


JSME-TJ Journal of Fluid Science and Technology Vol. 5, No. 2, 2010 340 Response of the Fully Developed Pipe Flow to Rough Wall Disturbances (Mean Velocity Field)* Aung Thuyein WIN**, Shinsuke MOCHIZUKI** and Takatsugu KAMEDA** **Department of Mechanical Engineering, Yamaguchi University, 2-16-1, Tokiwadai, Ube, 755-8611, Japan. E-mail: [email protected] Abstract An experimental study was conducted in order to clarify the response of the fully developed pipe flow to d- and k-type wall roughness of various streamwise lengths. The measurements were set to emphasize on the response processes, which are deformation and relaxation of the mean velocity profile related to the strength and type of roughness. Under the same effective pressure drop, comparison of the mean velocity profiles and three common characteristics of boundary layer thicknesses (displacement, momentum, and energy) revealed that the initial stage of the response to the flow depends on the type of roughness. The total recovery length until the fully developed state depends only on the effective pressure drop caused by the rough wall. Key words: Pipe Flow, Rough Wall, Response, Turbulent Structure, d-type and k-type Roughness 1. Introduction Turbulent flow reveals its equilibrium situation which suddenly disturbed by roughness or obstacles. As passive means, wall roughness and obstacles, such as honeycomb and ring, have been examined as flow control devices. Logan and Phataraphruk(1) reported experimental data in a pipe flow disturbed by a ring. In their study, after passing over roughness element, the flow recovered in three stages (regions), namely, a jet region, an internal boundary layer region, and a similarity region. An extensive survey of the response after disturbances was presented by Smits and Wood(2), who also introduced step and impulse changes in wall surface roughness. The response of a high-Reynolds-number turbulent boundary layer to a sho

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