An experimental study of the wall-pressure fluctuations beneath low Reynolds number turbulent boundary layers

An investigation was undertaken to improve our understanding of low-Reynolds-number turbulent boundary layers flowing over a smooth flat surface in nominally zero pressure gradients. In practice, such flows generally occur in close proximity to a tripping device and, though it was known that the flows are affected by the actual low value of the Reynolds number, it was realized that they may also be affected by the type of tripping device used and variations in free-stream velocity for a given device. Consequently, the experimental programme was devised to investigate systematically the effects of each of these three factors independently. Three different types of device were chosen: a wire, distributed grit and cylindrical pins. Mean-flow, broadband-turbulence and spectral measurements were taken, mostly for values of Rθ varying between about 715 and about 2810. It was found that the mean-flow and broadband-turbulence data showed variations with Rθ, as expected. Spectra were plotted using scaling given by Perry, Henbest & Chong (1986) and were compared with their models which were developed for high-Reynolds-number flows. For the turbulent wall region, spectra showed reasonably good agreement with their model. For the fully turbulent region, spectra did show some appreciable deviations from their model, owing to low-Reynolds-number effects. Mean-flow profiles, broadband-turbulence profiles and spectra were found to be affected very little by the type of device used for Rθ ≈ 1020 and above, indicating an absence of dependence on flow history for this Rθ range. These types of measurements were also compared at both Rθ ≈ 1020 and Rθ ≈ 2175 to see if they were dependent on how Rθ was formed (i.e. the combination of velocity and momentum thickness used to determine Rθ). There were noticeable differences for Rθ ≈ 1020, but these differences were only convincing for the pins, and there was a general overall improvement in agreement for Rθ ≈ 2175.

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Numerical investigation of wall pressure fluctuations for zero and adverse pressure gradient turbulent boundary layers using synthetic anisotropic turbulence

23rd AIAA/CEAS Aeroacoustics Conference ◽

10.2514/6.2017-3200 ◽

2017 ◽

Author(s):

Nan Hu ◽

Nils Reiche ◽

Roland Ewert

Keyword(s):

Pressure Gradient ◽

Numerical Investigation ◽

Boundary Layers ◽

Pressure Fluctuations ◽

Adverse Pressure Gradient ◽

Turbulent Boundary Layers ◽

Wall Pressure ◽

Anisotropic Turbulence ◽

Wall Pressure Fluctuations

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Comparison of the wall pressure fluctuations in artificially generated turbulent spots, natural transition and turbulent boundary layers

10.2514/6.1988-409 ◽

1988 ◽

Author(s):

THOMAS MAUTNER

Keyword(s):

Boundary Layers ◽

Pressure Fluctuations ◽

Turbulent Boundary Layers ◽

Wall Pressure ◽

Turbulent Spots ◽

Wall Pressure Fluctuations

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Simulation of turbulent boundary layer wall pressure fluctuations via Poisson equation and synthetic turbulence

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.448 ◽

2017 ◽

Vol 826 ◽

pp. 421-454 ◽

Cited By ~ 15

Author(s):

Nan Hu ◽

Nils Reiche ◽

Roland Ewert

Keyword(s):

Flat Plate ◽

Boundary Layers ◽

Poisson Equation ◽

Pressure Fluctuations ◽

Turbulent Boundary Layers ◽

Wall Pressure ◽

Fluctuating Pressure ◽

Reynolds Number Flow ◽

Wall Pressure Fluctuations ◽

Interaction Term

Flat plate turbulent boundary layers under zero pressure gradient are simulated using synthetic turbulence generated by the fast random particle–mesh method. The stochastic realisation is based on time-averaged turbulence statistics derived from Reynolds-averaged Navier–Stokes simulation of flat plate turbulent boundary layers at Reynolds numbers $\mathit{Re}_{\unicode[STIX]{x1D70F}}=2513$ and $\mathit{Re}_{\unicode[STIX]{x1D70F}}=4357$. To determine fluctuating pressure, a Poisson equation is solved with an unsteady right-hand side source term derived from the synthetic turbulence realisation. The Poisson equation is solved via fast Fourier transform using Hockney’s method. Due to its efficiency, the applied procedure enables us to study, for high Reynolds number flow, the effect of variations of the modelled turbulence characteristics on the resulting wall pressure spectrum. The contributions to wall pressure fluctuations from the mean-shear turbulence interaction term and the turbulence–turbulence interaction term are studied separately. The results show that both contributions have the same order of magnitude. Simulated one-point spectra and two-point cross-correlations of wall pressure fluctuations are analysed in detail. Convective features of the fluctuating pressure field are well determined. Good agreement for the characteristics of the wall pressure fluctuations is found between the present results and databases from other investigators.

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