Department of Aerospace and Ocean Engineering


Structure of Vortical Separations


Perspective topview of an oil-flow on the bump


Surface mean pressures, oil flow visualizations, and 3-velocity-component laser-Doppler velocimeter measurements are presented for a turbulent boundary layer of thickness d over 2 axisymmetric bumps of height H = d, 2d and one symmetric bump of H = 2d. LDV data were obtained at one plane x/H > 3.26 for each case. Complex vortical separations occur on the leeside and merge into large stream-wise mean vortices downstream for the 2 axisymmetric cases. The near-wall flow (y+ < 90) is dominated by the wall. For the axisymmetric cases, the vortices in the outer region produce large turbulence levels near the centerline and appear to have low frequency motions that contribute to turbulent diffusion. For the case with a narrower spanwise shape, there are sharper separation lines and lower turbulence intensities in the vortical downstream flow.



Gwibo Byun, Roger L. Simpson and C.H. Long, A STUDY OF VORTICAL SEPARATION FROM THREE-DIMENSIONAL SYMMETRIC BUMPS, AIAA-2003-0641, 41st Aerospace Science Meeting and Exhibit, Reno, NV. (Accepted to AIAA Journal)

Roger L. Simpson, C.H. Long and G. Byun,  STUDY OF VORTICAL SEPARATION FROM AN AXISYMMETRY HILL, International Journal of Heat and Fluid Flow, Volume 23, Issue 5, October 2002, Pages 582-591


Data available for download

  Pressure data
            Pressure coefficient (CP)   : Large Bump3_Cp.dat (36KB), Small Bump3_Cp.dat(36KB), Bump1_Cp.dat(2KB)

            Pressure gradient : Large Bump3_Pgrad.dat(20KB), Small Bump3_Pgrad.dat(28KB)

            Vorticity flux : Large Bump3_Vflux.dat (20KB), Small Bump3_Vflux.dat(28KB)


  LDV data(ZIP files) : Please read information file, info.txt
            All profiles : Large bump3(126KB), Small bump3(120KB), Bump1(120KB)
            Friction velocity, Ut : Large Bump3_Utau.dat (1KB), Small Bump3_Utau.dat(1KB), Bump1_Utau.dat(1KB)


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Gwibo Byun

Graduate Research Assistant

Boundary Layer Research Laboratory

Virginia Tech