Abstract
Measurements of the spectral characteristics of the wall pressure fluctuations produced by a turbulent boundary layer flow over solid sinusoidal surfaces of moderate wave amplitude to wave-length ratios have been obtained. The wave amplitudes were sufficiently small so that the flow remained attatched. The results show that the root mean square pressure level reaches a maximum on the adverse pressure gradient side of the wave at a position somewhat before the trough. Spectral analysis of the pressure fluctuations in narrow frequency bands reveals considerable differences in low and high frequency behavior. At low frequencies, the peak fluctuation amplitude was found at the trough whereas at high frequencies, the peak occurs just after the crest and a minimum is found at the trough. Pressure fluctuations having streamwise correlation lengths on the order of or larger than the wavelength of the surface do not return to their equilibrium (crest) amplitudes as they travel the length of a wave. Pressure fluctuations having streamwise correlation lengths about one order of magnitude less than a wavelength return exactly to their equilibrium amplitudes. Two-point correlation measurements show a decrease in longitudinal coherence on the adverse pressure gradient side of the wave at low frequencies and a considerable increase over a broad frequency range on the positive pressure gradient side. No change is found in the lateral coherence.
Similar content being viewed by others
Abbreviations
- C f :
-
skin friction coefficient
- C p :
-
pressure coefficient
- C n :
-
Fourier amplitudes of the pressure coefficient
- C dp :
-
pressure drag coefficient
- d :
-
pinhole diameter
- f :
-
frequency
- h :
-
half the crest to trough distance
- h + :
-
nondimensional wave amplitude = \(\frac{{hu^* }}{v}\)
- k n :
-
wavenumber = \(\frac{{2\pi n}}{\lambda }\)
- k :
-
fundamental wavenumber = \(\frac{{2\pi }}{\lambda }\)
- l p :
-
pressure correlation length
- p s :
-
mean surface pressure
- P ∞ :
-
ambient pressure
- p :
-
fluctuating pressure
- p 2 :
-
mean square pressure
- q :
-
dynamic head = 1/2 ϱU ∞ 2
- R :
-
space-time correlation
- P λ :
-
Reynolds number based on wavelength = \(\frac{{U_\infty\lambda }}{v}\)
- R θ :
-
Reynolds number based on momentum thickness = \(\frac{{U_\infty\lambda }}{v}\)
- t :
-
time
- R ∞ :
-
free stream velocity
- U :
-
mean streamwise velocity
- U e :
-
streamwise velocity at the edge of the boundary layer
- u * :
-
friction velocity = \(\sqrt {{{\tau _w } \mathord{\left/ {\vphantom {{\tau _w } \rho }} \right. \kern-\nulldelimiterspace} \rho }} \)
- x :
-
streamwise coordinate
- y :
-
wall-normal coordinate
- z :
-
spanwise coordinate
- α+ :
-
non-dimensional wavelength = \(\left( {\frac{{2\pi }}{\lambda }} \right)\left( {\frac{v}{{u^* }}} \right)\) *)
- β:
-
phase of the cross-spectral density
- δ* :
-
boundary layer displacement thickness
- Γ long :
-
longitudinal coherency
- Γ lat :
-
lateral coherency
- λ:
-
wavelength of wavy surface
- v :
-
kinematic viscosity
- ω:
-
radian frequency = 2 π f
- Φ :
-
spectral or cross-spectral density
- φ n :
-
phase of the Fourier series
- ϱ :
-
density
- τ:
-
time delay
- τ w :
-
wall shear stress
- θ :
-
boundary layer momentum thickness
References
Bendat, J. S.; Piersol, A. G. 1971: Random Data: Analysis and Measurement, New York: Wiley & Sons
Blake, W. K. 1970: Turbulent boundary layer wall pressure fluctuations on smooth and rough walls. J. Fluid Mech. 44, 637–660
Brownell, W. F. 1968: An anechoic flow facility design for the Naval Ship Research and Development Center. Naval Ship Research and Development Center Report 2924
Buckles, J. J.; Hanratty, T. J.; Adrian, R. 1984: Turbulent flow over large-amplitude wavy surfaces. J. Fluid Mech. 140, 27–44
Corcos, G. M. 1963: The resolution of pressure in turbulence. J. Acoust. Soc. Am. 35, 192–199
De Metz, F. C.; Casarella, M. J. 1973: An experimental study of the intermittent properties of the boundary layer pressure field during transition on a flat plate. Naval Ship Research and Development Center Report 4140
Emmerling, R. 1973: Instantaneous structure of the wall pressure under a turbulent boundary layer flow. Max Planck Institut für Strömungsforschung, Göttingen, Report no. 56/1973
Farabee, T. M. 1986: An experimental investigation of wall pressure fluctuations beneath non-equilibrium turbulent flows. Ph.D. Thesis, Catholic University of America
Frederick, K. A.; Hanratty, T. J. 1988: Velocity measurements for a turbulent nonseparated flow over solid waves. Exp. Fluids 6, 477–486
Hsu, S.; Kennedy, J. F. 1971: Turbulent flow in wavy pipes. J. Fluid Mech. 47, 481–502
Kendall, J. M. 1970: The turbulent boundary layer over a wall with progressive surface waves. J. Fluid Mech. 41, 259–281
Kraichnan, R. H. 1956: Pressure fluctuations in turbulent flow over a flat plate. J. Acoust. Soc. Am. 28, 378–390
Kuzan, J. D.; Hanratty, T. J.; Adrian, R. J. 1989: Turbulent flows with incipient separation over solid waves. Exp Fluids 6, 88–98
Leehey, P. 1989: Dynamic wall pressure measurements. In: Advances in Fluid Mechanics Measurements. Lecture Notes in Engineering, (ed. Gad-el-Hak, M.) Berlin Heidelberg New York: Springer
Motzfeld, H. 1937: Turbulent flow on wavy walls. Z. Angew. Math. Mech. 17, 193–212
Schewe, G. 1983: On the structure and resolution of wall pressure fluctuations associated with turbulent boundary layer flow. J. Fluid. Mech. 134, 311–328
Schloemer, H. 1966: Effects of pressure gradients on turbulent boundary layer wall pressure fluctuations. J. Acoust. Soc. Am. 42, 93–113
Sigal, A. 1971: An experimental investigation of the turbulent boundary layer over a wavy wall. Ph.D. Thesis, California Institute of Technology
White, F. M. 1974: Viscous fluid flow. New York: McGraw-Hill
Willmarth, W. W. 1975: Pressure fluctuations beneath turbulent boundary layers. Annu. Rev. Fluid Mech. 7, 13–38
Zilker, D. P.; Cook, G. W.; Hanratty, T. J. 1977: Influence of the amplitude of a solid wavy wall on a turbulent flow, part 1: non-separated flows. J. Fluid Mech. 82, 29–51
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Handler, R.A. Turbulent wall pressure fluctuations over wavy surfaces. Experiments in Fluids 10, 33–40 (1990). https://doi.org/10.1007/BF00187870
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00187870