This paper reports an investigation of the effects of surface conditions of forward-facing steps (FFS) on turbulent flows. Three surface conditions including one smooth step and two rough step surfaces created using sandpapers were studied. A particle image velocimetry (PIV) technique was used to conduct velocity measurements at several locations downstream, and the statistics up to 60 step heights are reported. The step height was maintained at 6 mm, and three Reynolds numbers of Reh = 1600, 3200, and 4800, where Reh is based on the step height and freestream mean velocity, were studied. The results indicate that the reattachment length of a FFS increases with Reynolds number but decreases with increasing surface roughness. The proper orthogonal decomposition (POD) results showed the step roughness affects even the large-scale structures.
Turbulent Flows Over Forward Facing Steps With Surface Roughness
University of Ontario Institute of Technology,
2000 Simcoe Street North,
Oshawa, ON L1H 7K4, Canada
Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received November 3, 2014; final manuscript received June 25, 2015; published online September 3, 2015. Assoc. Editor: Mark F. Tachie.
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Shao, W., and Agelin-Chaab, M. (September 3, 2015). "Turbulent Flows Over Forward Facing Steps With Surface Roughness." ASME. J. Fluids Eng. February 2016; 138(2): 021103. https://doi.org/10.1115/1.4031258
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