The Theory of Sound Propagation in a Fluid Half‐Space Bounded by a Rigid Surface

1970 ◽  
Vol 48 (6A) ◽  
pp. 1332-1332
Author(s):  
S. L. Self
Keyword(s):  
Half Space ◽  
Sound Propagation ◽  
Rigid Surface

The interaction of sound with low Mach number wall turbulence, with application to sound propagation in turbulent pipe flow

1979 ◽  
Vol 94 (4) ◽  
pp. 729-744 ◽  
Author(s):  
M. S. Howe
Keyword(s):  
Mach Number ◽  
Pipe Flow ◽  
Sound Propagation ◽  
Turbulent Pipe Flow ◽  
Wall Turbulence ◽  
Rigid Surface ◽  
Low Mach Number ◽  
Flow Equations ◽  
Wide Range ◽  
Good Agreement

This paper discusses the influence of turbulence convection on the formation of acoustic momentum and thermal boundary layers over a rigid surface in the presence of a low Mach number wall-turbulence shear flow. Equations which determine the modified boundary-layer profiles are obtained from a consideration of the relaxation of coherent perturbations in the Reynolds stress. These equations can be solved analytically for a wide range of conditions which are investigated in detail. The theory is applied to the problem of sound propagation in fully-developed turbulent pipe flow, and at low Mach numbers good agreement is obtained between predicted acoustic attenuation rates and experimental results available in the literature.

Friction Reduction in the Sliding of an Elastic Half-Space Against a Rigid Surface Due to Incident Rectangular Dilatational Waves

1999 ◽  
Vol 122 (1) ◽  
pp. 10-15 ◽  
Author(s):  
George G. Adams
Keyword(s):  
Normal Stress ◽  
Half Space ◽  
Coefficient Of Friction ◽  
Tangential Velocity ◽  
Elastic Half Space ◽  
Body Waves ◽  
Friction Reduction ◽  
Rigid Surface ◽  
Rectangular Wave ◽  
The Coefficient Of Friction

The steady sliding of a flat homogeneous and isotropic elastic half-space against a flat rigid surface, under the influence of incident plane dilatational waves, is investigated. The interfacial coefficient of friction is constant with no distinction between static and kinetic friction. It is shown here that the reflection of a harmonic wave under steady sliding consists of a pair of body waves (a plane dilatational wave and a plane shear wave) radiated from the sliding interface. Each wave propagates at a different angle such that the trace velocities along the interface are equal and supersonic. The angles of wave propagation are determined by the angle of the incident wave, by the Poisson’s ratio, and by the coefficient of friction. The amplitude of the incident waves is subject only to the restriction that the perturbations in interface contact pressure and tangential velocity satisfy the inequality constraints for unilateral sliding contact. It is also found that an incident rectangular wave can allow for relative sliding motion of the two bodies with a ratio of remote shear to normal stress which is less than the coefficient of friction. Thus the apparent coefficient of friction is less than the interface coefficient of friction. This reduction in friction is due to periodic stick zones which propagate supersonically along the interface. The influences of the angle, amplitude, and shape of the incident rectangular wave, the interfacial friction coefficient, the sliding speed, and of the remotely applied normal stress, on friction reduction are determined. Under appropriate conditions, the bodies can move tangentially with respect to each other in the absence of an applied shear stress. [S0742-4787(00)00201-0]

scholarly journals Transient frictionless contact of a rough rigid surface on a viscoelastic half-space

2017 ◽  
Vol 113 ◽  
pp. 279-285 ◽  
Author(s):  
R. Bugnicourt ◽  
P. Sainsot ◽  
N. Lesaffre ◽  
A.A. Lubrecht
Keyword(s):  
Half Space ◽  
Rigid Surface ◽  
Frictionless Contact

Radiation of Body Waves Induced by the Sliding of an Elastic Half-Space Against a Rigid Surface

1999 ◽  
Vol 67 (1) ◽  
pp. 1-5 ◽  
Author(s):  
G. G. Adams
Keyword(s):  
Friction Coefficient ◽  
Half Space ◽  
Coefficient Of Friction ◽  
Wave Train ◽  
Tangential Velocity ◽  
Body Waves ◽  
Rigid Surface ◽  
Plane Shear ◽  
Interface Friction ◽  
The Coefficient Of Friction

The steady sliding of a flat half-space against a rigid surface with a constant interfacial coefficient of friction is investigated. It is shown here that steady sliding is compatible with the formation of a pair of body waves (a plane dilatational wave and a plane shear wave) radiated from the sliding interface. Each wave propagates at a different angle such that the trace velocities along the interface are equal and supersonic with respect to the elastic medium. The angles of wave propagation are determined by the Poisson’s ratio and by the coefficient of friction. The amplitude of the waves are indeterminant, subject only to the restriction that the perturbations in interface contact pressure and tangential velocity satisfy the inequality constraints for unilateral sliding contact. It is also found that a rectangular wave train, or a rectangular pulse, can allow for motion of the two bodies with a ratio of remote shear to normal stress which is less than the coefficient of friction. Thus the apparent coefficient of friction is less than the interface coefficient of friction. Furthermore it is shown that the apparent friction coefficient decreases with increasing speed even if the interface friction coefficient is speed-independent. This result supports the interpretation of certain friction behavior as being a consequence of the dynamics of the system, rather than strictly as an interface property. In fact no distinction is made between the static and kinetic interface friction coefficients. [S0021-8936(00)02101-2]

The Accuracy of Doubly Asymptotic Approximations for an Acoustic Half-Space

1992 ◽  
Vol 114 (4) ◽  
pp. 555-563 ◽  
Author(s):  
M. Hasheminejad ◽  
T. L. Geers
Keyword(s):  
Half Space ◽  
Acoustic Impedance ◽  
Spherical Surface ◽  
Broad Band ◽  
Asymptotic Approximations ◽  
Rigid Surface ◽  
Planar Boundary ◽  
First Order ◽  
Pressure Surface ◽  
Bispherical Coordinates

The accuracy of doubly asymptotic approximations (DAAs) for acoustic half-space problems is assessed by examining their performance for a canonical problem in bispherical coordinates. Exact specific acoustic impedance curves for axisymmetric modal vibrations of a spherical surface near a planar boundary are generated, and corresponding curves based on the first-order DAA and the curvature-corrected DAA are compared with their exact counterparts. The comparisons show that the curvature-corrected DAA is substantially more accurate than the first-order DAA. Also, the curvature-corrected DAA is found to be satisfactory for broad-band excitations regardless of the sphere’s proximity to a compliant (zero-pressure) surface; for a rigid surface, the approximation is satisfactory only if the sphere is located at least one diameter away from the boundary.

Sign in / Sign up

Export Citation Format

Share Document