This paper presents results of an experimental research conducted to study roughness effects downstream of a forward facing step (FFS). A rough surface and a hydraulically smooth surface were used as a rough-FFS and a smooth-FFS, respectively. The upstream condition was kept smooth. Particle image velocimetry (PIV) technique was used for the velocity measurements. The Reynolds number based on the step height (h) and freestream velocity of the approach flow was kept constant at 8685. The results show that the mean reattachment length for the smooth-FFS (SM-SM) is 1.9h. Roughness reduced the peak values of the streamwise mean velocity, Reynolds shear stress and turbulent kinetic energy by 3%, 45% and 16.7% respectively in the recirculation region. In the early redevelopment region, roughness also reduced the peak values of turbulent kinetic energy and the Reynolds shear stress by 41% and 22% respectively.
- Fluids Engineering Division
Roughness Effect Downstream of Flow Over a Forward Facing Step
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Afriyie, YY, Essel, EE, Thacher, EW, & Tachie, MF. "Roughness Effect Downstream of Flow Over a Forward Facing Step." Proceedings of the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. Volume 1D, Symposia: Transport Phenomena in Mixing; Turbulent Flows; Urban Fluid Mechanics; Fluid Dynamic Behavior of Complex Particles; Analysis of Elementary Processes in Dispersed Multiphase Flows; Multiphase Flow With Heat/Mass Transfer in Process Technology; Fluid Mechanics of Aircraft and Rocket Emissions and Their Environmental Impacts; High Performance CFD Computation; Performance of Multiphase Flow Systems; Wind Energy; Uncertainty Quantification in Flow Measurements and Simulations. Chicago, Illinois, USA. August 3–7, 2014. V01DT27A007. ASME. https://doi.org/10.1115/FEDSM2014-21280
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