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Lee, Jae Hwa
Flow Physics and Control Lab
Research Interests
  • Turbulent Flow Physics and Control
  • Incompressible and Compressible Flows
  • Fluid-Structure Interaction
  • Multi-Phase Flow with Heat Transfer

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Turbulent boundary layer flow with a step change from smooth to rough surface

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Title
Turbulent boundary layer flow with a step change from smooth to rough surface
Author
Lee, Jae Hwa
Issue Date
2015-08
Publisher
ELSEVIER SCIENCE INC
Citation
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, v.54, pp.39 - 54
Abstract
A direct numerical simulation (DNS) dataset of a turbulent boundary layer (TBL) with a step change from a smooth to a rough surface is analyzed to examine the characteristics of a spatially developing flow. The roughness elements are periodically arranged two-dimensional (2-D) spanwise rods, with the first rod placed 80. θin downstream from the inlet, where θin denotes the inlet momentum thickness. Based on an accurate estimation of relevant parameters, clear evidence for mean flow universality is provided when scaled properly, even for the present roughness configuration, which is believed to have one of the strongest impacts on the flow. Compared to previous studies, it is shown that overshooting behavior is present in the first- and second-order statistics and is locally created either within the cavity or at the leading edge of the roughness depending on the type of statistics and the wall-normal measurement location. Inspection of spatial two-point correlations of the streamwise velocity fluctuations shows a continuous increase of spanwise length scales of structures over the rough wall after the step change at a greater growth rate than that over smooth wall TBL flow. This is expected because spanwise energy spectrum shows presence of much energetic wider structures over the rough wall. Full images of the DNS data are presented to describe not only predominance of hairpin vortices but also a possible spanwise scale growth mechanism via merging over the rough wall.
URI
https://scholarworks.unist.ac.kr/handle/201301/12282
URL
http://www.sciencedirect.com/science/article/pii/S0142727X15000478
DOI
10.1016/j.ijheatfluidflow.2015.05.001
ISSN
0142-727X
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