Sonic wave, propagation

Sonic wave propagation. Sonic waves differ from pressure pulses in two respects ... 

Three types of sonic waves propagate from the site of an earthquake longitudinal transverse and surface waves. Which type arrives first Which type creates the most devastation (i.e., largest amplitude) ... 

Cheng, L. Y, D. A. Drew, and R. T. Lahey, Jr., 1983, An Analysis of Wave Dispersion, Sonic Velocity and Critical Flow in Two-Phase Mixtures, NUREG-CR-3372, US NRC, Washington, DC. (3) Cheng, L. Y., D. A. Drew, and R. T. Lahey, Jr., 1985, An Analysis of Wave Propagation in Bubbly, Two-Component, Two Phase Flow, Trans. ASMEJ. of Heat Transfer, 107 402-408. (3)... 

For blast resistant design, the most significant feature of an explosion is the sudden release of energy to the atmosphere which results in a pressure transient, or blast wave. The blast wave propagates outward in all directions from the source at supersonic or sonic speed. The magnitude and shape of the blast wave depends on the nature of the energy release and on the distance from the explosion epicenter. The characteristic shapes of blast waves are shown in Figure 3.1. 

Wallner lines are formed when sonic waves generated during fracture interact with principal stress driving the propagating crack front. Wallner lines appear as a series of arc shaped steps as shown in Figure 2.33. 

Sonic waves comprise linear propagation of regions of compression and rarefaction, and are normally quite harmless. The systems normally adjust in-phase or with a lag time depending on the frequency, and the laws of thermodynamics are obeyed (Blandamer, 1973). However, at ultrasonic frequencies, if the power is increased, micro-cavita-... 

As an acoustic wave propagates it is attenuated by absorption in the medium. This process results in a radiation pressure which is proportional to the absorbed energy and acoustic streaming (vide supra). The pressure can be measured from the height difference of liquids in two connected tubes, one being sonicated and the other not, at different values of z where z is the distance from the emitter surface. If we let I2 be the sound intensity at z and Io the sound intensity at the surface of the emitter then,... 

Sonicated particles can also have their motion influenced by the presence of cavities remote from their surfaces. This may arise through the action of shock waves propagated from the collapse of unstable cavities. Since these shock waves have been suggested to be capable of causing metal particles to fuse, it is not surprising that they are capable of increasing the number of interparticle collisions. In turn, these, like microjets, can result in the oscillation of the particles about their Dysthe equilibrium positions with such rapidity that NMR line-narrowing can be achieved. 

Electro-optic and magneto-optic phenomena contain terms of nonlinear optics effects (see Eqs. (4.32), (4.33), (4.36), and (4.39)). On the other hand, acousto-optic effects which arise from a periodical density fluctuation of the medium, analogous to the Brillouin scattering phenomenon, do not contain terms of nonlinear optics, as a general rule.5) The perturbation of light propagation by sonic waves differs from that induced by electric and magnetic fields. As the electric susceptibility, xe, is a function of the density of the medium, it will be influenced by the periodical density fluctuation induced in a medium by sound waves. 

The principle underlying the application of sound is that the vibration created by the energy associated with the transmission of sound will disturb and dislodge deposits on surfaces, i.e. "to shake" the deposit free. Cavitation produced by the propagation of sonic waves in the continuous phase near the deposit surface, can also assist the removal process. 

The product mixture which exists in a particular plane in the reaction zone behind the detonation front obeys the Chapman-Jouguet (C-J) hypothesis. In essence, the C-J or sonic plane differentiates between the part of the reaction zone where the detonative decomposition is completed (and exothermic reactions supply energy with the local speed of sound to the detonation front) and that part in which further energy release due to reactions among the products is not supplied sufficiently rapidly to maintain steady wave propagation. 

The classic detonation theory has proved that the stable/steady detonation waves of explosives propagate with CJ rate and there are sonic flows in the boundaries of detonation reactions. If the detonation waves propagate faster than CJ rate, there are subsonic flows in the boundaries of reactions. The classic detonation theory predicted that there were sustaining stable/steady detonation waves and possible special unsustaining detonation waves. The spread rates of ultrasonic waves in the boundaries of reactions are eigenvalue detonation rates. 

Sonic modulus n. The tensUe/compressive modulus ( ) estimated by measurement of sound-wave propagation in a material. ASTM Test C 769 (section 15.01) describes such a method. 

Sonic and ultrasonic test methods use elastic waves propagating in solid or fluid media and are classified into active and passive methods. The former requires emission of waves into the test object the latter, waves emitted by the material itself... 

A child tosses a stone into a lake. He delights in watching capillary waves propagate by forming circular ripples on the water s surface. All of us have heard the sonic boom produced by an aircraft crossing the sound barrier. But how many of us are aware that we can also observe shock waves of capillary origin every day when we turn our kitchen faucet on on the bottom of the sink water flows outward as a thin film. But a few centimeters away from the center, we see a hydraulic jump—very similar to a shock ... 

Due to the number of fluids investigated, results are reported in Table Il-a and Table Il-b and some typical cases are plotted in figures 1 and 2. A discontinuity in the sound velocity versus pressure curves can be observed in some lubricants (fig. 2). This discontinuity is interpreted 24 by the apparition of an amorphous phase (a solid like phase) in the sample. Due to the hydrostatic pressure, molecules are compressed and the free volume available is also reduced. Ultra sonic waves are sensitive to this evolution longitudinal waves introduced local pressure fluctuations and the speed of propagation is dependant of the density and the molecular state of the tested sample. 

It has been suggested by Morgan [30] and others [28] that the sonic modulus (i.e. the extensional modulus measured at high frequencies by a wave-propagation technique) can be used to obtain a direct measure of molecular orientation in a manner analogous to the derivation of the so-called optical orientation function /o = (1 - sin2 0) from the birefringence. 

The dynamic elastic modulus is determined by measuring the wave propagation velocity of ultrasonic pulses in the material. It is a nondestructive method, based on the dependence between the elastic modulus and the velocity of the propagation of the sonic or ultrasonic waves (mechanical vibrations). The method is very precise. The apparatus is not complicated, and it is possible to measure the dynamic elastic modulus at high temperatures. It is measured according to the standards ASTM C 1198-01 [53] and ISO 3312 1987 [54], and the elastic modulus of carbon materials is measured according to ASTM standard C747 [55]. 

Elastic (sonic) waves are also generated during a fracture event, and the locus of intersections of these waves with a propagating crack front gives rise to another type of surface feature known as a Wallner line. Wallner lines are arc shaped, and they provide information regarding stress distributions and directions of crack propagation. 

This idealization of concentration-wave propagation through a particle phase is illustrated in Figure 6.2. It considers the particles to be arranged in regular, horizontal layers, so as to capture the essential feature of onedimensional behaviour. We now see how this idealized arrangement enables an expression for the dynamic-wave velocity to be estimated by direct analogy with the expression of eqn (6.1) for the sonic velocity in a compressible fluid. 

The basics of the method are simple. Reflections occur at all layers in the subsurface where an appreciable change in acoustic impedance is seen by the propagating wave. This acoustic impedance is the product of the sonic velocity and density of the formation. There are actually different wave types that propagate in solid rock, but the first arrival (i.e. fastest ray path) is normally the compressional or P wave. The two attributes that are measured are... 

Deflagration A propagating chemical reaction of a substance in which the reaction front advances into the unreacted substance at less than the sonic velocity in the unreacted material. Where a blast wave is produced that has the potential to cause damage, the term explosive deflagration may be used. 

---