Alan B. Coppens
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View article: Propagation of sound in fluid wedge overlying a fast bottom
Propagation of sound in fluid wedge overlying a fast bottom Open
The method of images has been applied to the problems of up-, down-, and cross-slope propagation in a fluid wedge with pressure release upper surface and a bottom consisting of an absorbing fluid with greater density and sound speed. A com…
View article: Finite-Amplitude Standing Waves in a Cavity with Boundary Perturbations.
Finite-Amplitude Standing Waves in a Cavity with Boundary Perturbations. Open
Finite amplitude acoustic standing waves in a rectangular air-filled cavity with various wedge-shape boundary perturbations were studied both experimentally and theoretically. The experimental results show that geometrical perturbations al…
View article: Propagation of sound from water into a sloping fast bottom
Propagation of sound from water into a sloping fast bottom Open
When sound is propagated from large distances toward the apex of a fluid wedge overlying a fluid bottom in which the speed of sound is greater, acoustical energy must be transmitted into the bottom as the various normal modes in the wedge …
View article: Two computer programs for the evaluation of the acoustic pressure amplitude and phase at the bottom of a wedge-shaped, fluid layer overlying a fast, fluid half space.
Two computer programs for the evaluation of the acoustic pressure amplitude and phase at the bottom of a wedge-shaped, fluid layer overlying a fast, fluid half space. Open
The pressure amplitude and phase distribution along the interface between a tapered fluid layer and an underlying fast fluid bottom were investigated theoretically. Two computer models, both based on the method of images, were designed: WE…
View article: Finite-amplitude standing waves in rectangular cavities with degeneracies and weakly-perturbed walls
Finite-amplitude standing waves in rectangular cavities with degeneracies and weakly-perturbed walls Open
It was observed and reported in an earlier paper [“Finite-amplitude standing waves within real cavities.” Alan B. Coppens and James V. Sanders, J. Acoust. Soc. Am. 58, 1133–1140 (1975)] that when there was a degeneracy involving any normal…
View article: Theoretical study of the propagation of sound into a fast bottom from an overlying fluid wedge
Theoretical study of the propagation of sound into a fast bottom from an overlying fluid wedge Open
Propagation of an acoustical wave toward the apex of a wedge-shaped fluid layer with sound speed C1 overlying a fluid bottom of higher speed of sound, C2, leads to the generation of a well-collimated beam of energy transmitted into the und…
View article: A Semi-Empirical, Nonlinear Wave Equation for Standing Waves in Cavities
A Semi-Empirical, Nonlinear Wave Equation for Standing Waves in Cavities Open
A one-dimensional nonlinear wave equation with loss term based on the Rayleigh-Kirchhoff predictions for wall losses and speed-of-sound dispersion was found to be only partially correct in describing standing waves in tubes because the obs…
View article: Computerized Study of Finite-Amplitude Standing Waves in a Duct
Computerized Study of Finite-Amplitude Standing Waves in a Duct Open
A one-dimensional model of a finite-amplitude standing wave confined to a duct (wherein boundary-layer effects at the walls produce energy losses greater than those arising from viscous and thermal effects in the body of the fluid) has bee…
View article: Limits of Validity of a Perturbation Solution for a Finite-Amplitude Standing Wave Confined to a Duct
Limits of Validity of a Perturbation Solution for a Finite-Amplitude Standing Wave Confined to a Duct Open
The range of validity of a perturbation solution to the problem of nonlinear standing waves in rigid-walled ducts is discussed in the light of some recent published and unpublished data from a number of investigators. While most of the dat…
View article: Finite-Amplitude Traveling Waves in Ducts
Finite-Amplitude Traveling Waves in Ducts Open
A nonlinear, dissipative, acoustic wave equation generalized from the linear, dissipative wave equation valid for one-dimensional motion in a duct (where the dominant absorptive mechanism is the energy loss in the boundary layer) has been …
View article: Propagation of Acoustic Transients in a Fluid Layer
Propagation of Acoustic Transients in a Fluid Layer Open
Approximate solutions of the wave equation have been obtained for some acoustic transients propagated radially outward from a cylindrical source of radius a in a fluid-layer with pressure-release (or rigid) surfaces. The earliest portions …
View article: Theoretical Investigation of Finite-Amplitude Effects for Acoustic Standing Waves in Cavities
Theoretical Investigation of Finite-Amplitude Effects for Acoustic Standing Waves in Cavities Open
The generation of overtones by finite-amplitude processes in rigid-walled cylindrical cavities with large length-to-diameter ratios is studied. An extension of the Keck-Beyer perturbation technique leads to a set of iterative equations val…
View article: Experimental Investigation of Finite-Amplitude Standing Waves in Air-Filled Tubes
Experimental Investigation of Finite-Amplitude Standing Waves in Air-Filled Tubes Open
The air in a rigid-walled tube of fixed length was excited into vibration by means of a piston driven by an electrodynamic shaker. At the fundamental frequency (100 Hz), or one of the overtones of the tube, the pressure at the fixed end wa…
View article: Parameter of Nonlinearity for Liquids
Parameter of Nonlinearity for Liquids Open
The ratio of B/A in the adiabatic expansion for pressure p as a function of the density ρ, p=po+A (ρ−ρo)/ρo+B (ρ−ρo)2/2ρo2 is reported for a number of organic liquids. A detailed comparison of these values, obtained from measurement of the…