Color-coded visualization of microbubble clouds interacting with eddies in a spatially developing turbulent boundary layer

• Park, Hyun Jin

• Saito, Daichi

• Tasaka, Yuji

• Murai, Yuichi

抄録

Three-dimensional distribution of microbubbles dispersed in a turbulent boundary layer spatially developing along a flat plate is investigated experimentally. The aim of study is to find out visually how microbubbles interact with turbulent eddies to achieve frictional drag reduction on a wall. Setting conditions of the experiments are stream Reynolds number up to 2.3 x 10(4), microbubble volume fraction inside boundary layer less than 10(-5), and microbubble Stokes number smaller than 10(-3). Stream-wise vortices in the boundary layer were visualized by flake optics, of which spacing expands with injection of microbubbles. 3-D microbubble distributions were visualized by a color-coded volumetric illumination. The result showed preferentially accumulated microbubble clouds to low-speed streaks close to viscous sublayer and to hair-pin vortices in the buffer layer, leading to reduced diffusivity of microbubbles relative to the turbulent momentum diffusivity.

収録刊行物

• Experimental thermal and fluid science

  Experimental thermal and fluid science 109 109919-, 2019-12

  Elsevier

キーワード

• Drag reduction
• Microbubbles
• Turbulent boundary layer
• Flow visualization

詳細情報

• CRID: 1050571782525421184
• NII論文ID: 120007173931
• HANDLE: 2115/83367
• ISSN: 08941777
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles