14 research outputs found
Sound radiation from a turbulent boundary layer
No full textSound radiation due to fluctuating viscous wall shear stresses in a plane turbulent boundary layer is investigated by a two-stage procedure using direct numerical simulation (DNS) databases for incompressible turbulent Poiseuille flow in a plane channel, at Reynolds numbers up to Re?=1440. The power spectral density of radiated pressure and spectra of sound power per unit wall area are calculated in the low Mach number limit by substituting source terms obtained from DNS into a Ffowcs Williams–Hawkings wave equation and using a half-space Green function. The same DNS data are used to predict the spectrum of turbulent boundary layer noise measured in a diffuser downstream of a fully developed channel flow [Greshilov and Mironov, Sov. Phys. Acoust. 29, 275 (1983)]. The measured spectrum is ~15 dB higher at low frequencies, but converges with the prediction at high frequencies
The use of distributed pressure receivers based on elastic piezoelectric composite materials for measuring the hydrodynamic noise produced by a near-wall turbulence
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Influence of surfactant admixtures on the acoustic characteristics of a closed hydraulic loop
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On applicability of confluence analysis in cathodoluminescence microscopy for interval estimation of diffusion lengths of minority carriers and depths of subsurface regions with depletion of majority carriers
No full textOn the choice of initial approximation in the problem of parameter identification of direct-gap semiconductors by cathodoluminescence microscopy
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The Link Between Wall Pressure Spectra and Radiated Sound from Turbulent Boundary Layers
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