Skip to main content
    • Aa
    • Aa

Aerodynamic noise from a poroelastic edge with implications for the silent flight of owls

  • Justin W. Jaworski (a1) and N. Peake (a1)

The interaction of a turbulent eddy with a semi-infinite poroelastic edge is examined with respect to the effects of both elasticity and porosity on the efficiency of aerodynamic noise generation. The scattering problem is solved using the Wiener–Hopf technique to identify the scaling dependence of the resulting aerodynamic noise on plate and flow properties, including the dependence on a characteristic flow velocity $U$. Special attention is paid to the limiting cases of porous-rigid and impermeable–elastic plate conditions. Asymptotic analysis of these special cases reveals parametric limits where the far-field acoustic power scales like ${U}^{6} $ for a porous edge, and a new finite range of ${U}^{7} $ behaviour is found for an elastic edge, to be compared with the well-known ${U}^{5} $ dependence for a rigid impermeable edge. Further numerical results attempt to address how trailing-edge noise may be mitigated by porosity and flexibility and seek to deepen the understanding of how owls hunt in acoustic stealth.

Corresponding author
Email address for correspondence:
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

R. K. Amiet 1975 Acoustic radiation from an airfoil in a turbulent stream. J. Sound Vib. 41 (4), 407420.

J. R. Barone & W. F. Schmidt 2005 Polyethylene reinforced with keratin fibres obtained from chicken feathers. Compos. Sci. Technol. 65, 173181.

D. B. Bliss 1982 Study of bulk reacting porous sound absorbers and a new boundary condition for thin porous layers. J. Acoust. Soc. Am. 71 (3), 533545.

P. A. Cannell 1975 Edge scattering of aerodynamic sound by a lightly loaded elastic half-plane. Proc. R. Soc. Lond. A 347 (1649), 213238.

P. A. Cannell 1976 Acoustic edge scattering by a heavily loaded elastic half-plane. Proc. R. Soc. Lond. A 350 (1660), 7189.

T. W. Carpenter 1992 Utility of wing length, tail length and tail barring in determining the sex of Barred Owls collected in Michigan and Minnesota. The Condor 94, 794795.

T. P. Chong , P. F. Joseph & M. Gruber 2013 Airfoil self noise reduction by non-flat plate type trailing edge serrations. Appl. Acoust. 74, 607613.

D. G. Crighton 1972 Acoustic edge scattering of elastic surface waves. J. Sound Vib. 22 (1), 2532.

D. G. Crighton 2001 Asymptotic factorization of Wiener–Hopf kernels. Wave Motion 33, 5165.

D. G. Crighton & F. G. Leppington 1973 Singular perturbation methods in acoustics: diffraction by a plate of finite thickness. Proc. R. Soc. Lond. A 335 (1602), 313339.

N. Curle 1955 The influence of solid boundaries upon aerodynamic sound. Proc. R. Soc. Lond. A 231 (1187), 505514.

C. M. Earhart & N. K. Johnson 1970 Size dimorphism and food habits of North American owls. The Condor 72, 251264.

T. Geyer , E. Sarradj & C. Fritzsche 2010 Measurement of the noise generation at the trailing edge of porous airfoils. Exp. Fluids 48 (2), 291308.

H. D. Gruschka , I. U. Borchers & J. G. Coble 1971 Aerodynamic noise produced by a gliding owl. Nature 233, 409411.

M. Herr & W. Dobrzynski 2005 Experimental investigations in low-noise trailing-edge design. AIAA J. 43 (6), 11671175.

M. S. Howe 1978 A review of the theory of trailing edge noise. J. Sound Vib. 61 (3), 437465.

M. S. Howe 1979a On the added mass of a perforated shell, with application to the generation of aerodynamic sound by a perforated trailing edge. Proc. R. Soc. Lond. A 365 (1721), 209233.

M. S. Howe 1979b On the theory of unsteady high Reynolds number flow through a circular aperture. Proc. R. Soc. Lond. A 366 (1725), 205223.

M. S. Howe 1984 On the generation of sound by turbulent boundary layer flow over a rough wall. Proc. R. Soc. Lond. A 395 (1809), 247263.

M. S. Howe 1991a Aerodynamic noise of a serrated trailing edge. J. Fluids Struct. 5 (1), 3345.

M. S. Howe 1991b Noise produced by a sawtooth trailing edge. J. Acoust. Soc. Am. 90 (1), 482487.

M. S. Howe 1992 Sound produced by an aerodynamic source adjacent to a partly coated, finite elastic plate. Proc. R. Soc. Lond. A 436 (1897), 351372.

M. S. Howe 1993 Structural and acoustic noise produced by turbulent flow over an elastic trailing edge. Proc. R. Soc. Lond. A 442 (1916), 533554.

M. S. Howe 1998 Acoustics of Fluid-Structure Interactions. Cambridge University Press.

M. S. Howe 2001 Edge-source acoustic Green’s function for an airfoil of arbitrary chord, with application to trailing-edge noise. Q. J. Mech. Appl. Maths 54 (1), 139155.

M. S. Howe , M. I. Scott & S. R. Sipcic 1996 The influence of tangential mean flow on the Rayleigh conductivity of an aperture. Proc. R. Soc. Lond. A 452 (1953), 23032317.

H. C. Kranzer & J. Radlow 1962 Asymptotic factorization for perturbed Wiener–Hopf problems. J. Math. Anal. Appl. 4, 240256.

F. G. Leppington 1990 The effective boundary conditions for a perforated elastic sandwich panel in a compressible fluid. Proc. R. Soc. Lond. A 427 (1873), 385399.

M. J. Lighthill 1952 On sound generated aerodynamically. Part 1. General theory. Proc. R. Soc. Lond. A 211 (1107), 564587.

C. D. Marti 1990 Sex and age dimorphism in the Barn Owl and a test of mate choice. The Auk 107, 246254.

R. Martinez & S. E. Widnall 1980 Unified aerodynamic-acoustic theory for a thin rectangular wing encountering a gust. AIAA J. 18 (6), 636645.

P. A. Nelson 1982 Noise generated by flow over perforated surfaces. J. Sound Vib. 83 (1), 1126.

S. Oerlemans , M. Fisher , T. Maeder & K. Kögler 2009 Reduction of wind turbine noise using optimized airfoils and trailing-edge serrations. AIAA J. 47 (6), 14701481.

S. W. Rienstra 2007 Acoustic scattering at a hard-soft lining transition in a flow duct. J. Engng Maths 59 (4), 451475.

M. Roger & S. Moreau 2005 Back-scattering correction and further extensions of Amiet’s trailing-edge noise model. Part 1. Theory. J. Sound Vib. 286, 477506.

R. D. Sandberg & L. E. Jones 2011 Direct numerical simulations of low Reynolds number flow over airfoils with trailing-edge serrations. J. Sound Vib. 330, 38183831.

E. Sarradj , C. Fritzsche & T. Geyer 2011 Silent owl flight: flyover noise measurements. AIAA J. 49 (4), 769779.

B. Veitch & N. Peake 2008 Acoustic propagation and scattering in the exhaust flow from coaxial cylinders. J. Fluid Mech. 613, 275307.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Altmetric attention score