Turbulent flows with incipient separation over solid waves

Kuzan, John D.; Hanratty, Thomas J.; Adrian, Ronald J.

doi:10.1007/bf00207300

Cited by 50 publications

(39 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As concerns flow separation, zones of reverse flow are observed for ak]0.35. This value is larger than those found in previous studies [10,22,25]. However, this could be owing to the higher Re of our simulations.…”

Section: Discussioncontrasting

confidence: 56%

“…In our case also, at ak =0.35, small recirculating flow regions are observed, although they are not apparent in the mean flow at the streamwise sections presented in Figures 15 and 16. Usually, ak= 0.3 is indicated as the critical value at which separation starts (see, for instance, the experiments in Reference [25] and the simulations in Reference [10]). This discrepancy, however, can be owing to the fact that the Re in our simulations is significantly higher than in References [10,25], and this has the effect of delaying the flow separation, as observed in the previous section and in Reference [22].…”

Section: Effects Of the Wa6e Shapementioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional coarse large-eddy simulations of the flow above two-dimensional sinusoidal waves

Salvetti

Damiani

Beux

2001

Int. J. Numer. Meth. Fluids

View full text Add to dashboard Cite

Section: Discussioncontrasting

confidence: 56%

Section: Effects Of the Wa6e Shapementioning

confidence: 99%

Three-dimensional coarse large-eddy simulations of the flow above two-dimensional sinusoidal waves

Salvetti

Damiani

Beux

2001

Int. J. Numer. Meth. Fluids

View full text Add to dashboard Cite

“…Moving further away from the wall, the elliptic shape of the space-time correlation recurs in the outer region of the flow despite the shear layer. Comparing the influences from the lower and higher shear layers, it is considered that beside the shear layer the adverse pressure gradient [38][39][40][41][42], which is stronger near the wavy wall, may play an additional role in the invalidity of the elliptic model of the space-time correlation.…”

Section: Verificationmentioning

confidence: 99%

TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls

2014

View full text Add to dashboard Cite

The present experimental work is devoted to investigate a new space-time correlation model for the turbulent boundary layer over a flat and a wavy walls. A turbulent boundary layer flow at Re θ = 2 460 is measured by tomographic time-resolved particle image velocimetry (Tomo-TRPIV). The space-time correlations of instantaneous streamwise fluctuation velocity are calculated at 3 different wall-normal locations in logarithmic layer. It is found that the scales of coherent structure increase with moving far away from the wall. The growth of scales is a manifestation of the growth of prevalent coherent structures in the turbulent boundary layer like hairpin vortex or hairpin packets when they lift up. The resulting contours of the space-time correlation exhibit elliptic-like shapes rather than straight lines. It is suggested that, instead of Taylor hypothesis, the elliptic model of the space-time correlation is valid for the wallbounded turbulent flow over either a flat wall or a wavy wall. The elliptic iso-correlation curves have a uniform preferred orientation whose slope is determined by the convection velocity. The convection velocity derived from the space-time correlation represents the velocity at which the large-scale eddies carry small-scale eddies. The sweep velocity represents the distortions of the small-scale eddies and is intimately associated with the fluctuation velocity in the logarithmic layer of turbulent boundary layers. The nondimensionalized correlation curves confirm that the elliptic model is more proper for approximating the space-time correlation than Taylor hypothesis, because the latter can not embody the small-scale motions which have non-negligible distortions. A second flow over a wavy wall is also recorded using TRPIV. Due to the combined effect of shear layers and the adverse pressure gradient, the space-time correlation does not show an elliptic-like shape at some specific heights over the wavy wall, but in the outer region of the wavy wallbounded flow, the elliptic model remains valid.

show abstract

“…A comparison of these values with the results of Frederick and Hanratty (1988) indicates that the current results have been obtained in a regime where the phase angle between the wave profile and wall shear stress changes rapidly in a narrow range of ~ + values. It is also evident from the results of Kuzan et al (1989), that the flow over WS1 is non-separated and should show a weakly non-linear stress response.…”

Section: Mean Velocity Profiles and Flow Regimesmentioning

confidence: 71%

“…In contrast, previous investigations of turbulent flow over wavy boundaries have been motivated, among other thing, by an interest in the mechanism of wind generated waves, heat and mass transport enhancement, drag reduction, and turbulence modeling. Numerous references can be cited but we list here only a few of the more complete studies which include flows over non-separating (Kendall 1970;Hsu and Kennedy 1971 ;Zilker et al 1977), and separated flows (Buckles et al 1984;Kuzan et al 1989). The focus of attention in these studies, however, was primarily related to an interest in turbulence modeling, turbulence structure, and mass transfer phenomena.…”

mentioning

confidence: 99%

Turbulent wall pressure fluctuations over wavy surfaces

Handler

1990

Experiments in Fluids

View full text Add to dashboard Cite

Measurements of the spectral characteristics of the wall /2 pressure fluctuations produced by a turbulent boundary layer flow U~ over solid sinusoidal surfaces of moderate wave amplitude to waveu* length ratios have been obtained. The wave amplitudes were suffix ciently small so that the flow remained attatched. The results show y that the root mean square pressure level reaches a maximum on the z adverse pressure gradient side of the wave at a position somewhat ct + before the trough. Spectral analysis of the pressure fluctuations in narrow frequency bands reveals considerable differences in low and fl 6* high frequency behavior. At low frequencies, the peak fluctuation Flo, ~ amplitude was found at the trough whereas at high frequencies, the peak occurs just after the crest and a minimum is found at the Ft"t trough. Pressure fluctuations having streamwise correlation lengths v on the order of or larger than the wavelength of the surface do not return to their equilibrium (crest) amplitudes as they travel the co length of a wave. Pressure fluctuations having streamwise correlation lengths about one order of magnitude less than a wavelength ~b~ return exactly to their equilibrium amplitudes. Two-point correlation measurements show a decrease in longitudinal coherence on the T "C w adverse pressure gradient side of the wave at low frequencies and a 0 considerable increase over a broad frequency range on the positive pressure gradient side. No change is found in the lateral coherence.

show abstract

Turbulent flows with incipient separation over solid waves

Cited by 50 publications

References 9 publications

Three-dimensional coarse large-eddy simulations of the flow above two-dimensional sinusoidal waves

Three-dimensional coarse large-eddy simulations of the flow above two-dimensional sinusoidal waves

TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls

Turbulent wall pressure fluctuations over wavy surfaces

Contact Info

Product

Resources

About