Liquid longitudinal waves

For exciting the surface waves the traditional method of transforming of the longitudinal wave by the plastic wedge is used. The scheme of surface waves excitation is shown in fig. 1. In particular, it is ascertained that the intensity of the excitation of the surface wave is determined by the position of the extreme point of the exit of the acoustic beam relatively to the front meniscus of the contact liquid. The investigations have shown, that under the... 

This 1s a frequent occurrence since the natural longitudinal wave frequency of liquid Inside a process vessel Is typically 1n the range of 6 to 12 seconds, corresponding very closely to typical pitch and surge excitation frequencies of tankers, barges and sem1-submer 1b1es (10 - 16 seconds). 

In fluid media, such as gases or liquids and melts, which have no rigidity, only longitudinal waves can occur. In media that have rigidity but are incompressible, only transverse waves can occur. 

In solids the situation is more complicated than in liquids. Here we have two types of waves, viz. the longitudinal and the shear waves. In contrast with liquids the longitudinal wave in solids is not only determined by the bulk or compression modulus but also by the shear modulus, or alternatively by the Poisson ratio. 

Most applications of US-detection in liquids use compressive, longitudinal waves shear waves propagate over macroscopic distances in solids, but not in liquids, and other modes of US propagation are of little use with liquid samples. 

Recently, reliable relaxation experiments at liquid/liquid have been performed by different techniques. Bonfillon Langevin (1993) measured the dilational elasticity of different surfactants (Triton X-100, SDS in water and in 0.1 M NaCl) at water/air as well as alkane/water interfaces by a modified longitudinal wave damping method (cf. Section 6.3.1). While at the water/air interface, the behaviour of Triton X-100 could be described by a... 

Liquid Chemical Constituents Density, g/cm3 Longitudinal-Wave Phase Velocity, cm/usec... 

Ultrasonic Nebulizers. Ultrasound can be used to break up a liquid mass into smaller particles. In the ultrasonic nebulizer, an ultrasonic generator drives a piezoelectric crystal at a frequency between 200 kHz and 10 MHz. The surface of the liquid sample will breakdown into an aerosol when the longitudinal wave propagates from the surface of the crystal toward the liquid-air interface. The wavelength of the surface wave is given by the following equation ... 

In a solid, both longitudinal and transverse waves can be transmitted, whereas in gas and liquids, only longitudinal waves can be transmitted. In liquids, longitudinal vibrations of molecules generate compression and refractions, i.e., areas of high pressure and low local pressure. The latter gives rise to cavities or bubbles. 

A beam of ultrasonic waves generated by a transducer is directed on to the surface of the polymer which is immersed in a suitable liquid, for example water or silicone oil. Two refracted beams are produced, the higher velocity beam corresponding to a compressional or longitudinal wave, the other to a transverse or shear wave. There is also a reflected... 

Chu X. L., Velarde M. G. (1989). Transverse and Longitudinal Waves Induced and Sustained by Surfactant Gradients at Liquid-Liquid Interfaces. Journal of Colloid and Interface Science 131(2) 471-484... 

Figure 14.30 Temperature dependence of the relative absorption of the longitudinal wave at 2 MHz parallel (a ) and perpendicular (a ) to the axis of the mesogenic units of a side chain polymer liquid crystal with a polymethylsiloxane backbone. (Adapted from [17] by permission of Israel Institute of Technology.)...

In the experiments described in Section 3, surface wave motion was generated by small oscillations of a bar in a direction perpendicular to the surface. In another type of experiment for surfactant-containing interfaces, the bar receives small oscillations in a direction parallel to the surface and longitudinal wave motion ensues (Lucassen, 1968). Develop an analysis of this situation for the case of an insoluble surfactant film at a liquid-gas interface that remains flat during longitudinal wave motion. 

A longitudinal wave propagation approach has been adopted in view of the problems of applying capillary wave techniques to liquid/liquid interfaces. These arise from two quarters. Firstly the variation of damping coefficient with elastic modulus can be shown (12) to be negligible at sufficiently high and low elastic moduli. 

Sound consists of longitudinal pressure waves, i.e., the particles of the medium are displaced parallel to the propagation axis (in transverse waves such as ripples on a water surface, the oscillating displacement of the liquid particles is perpendicular to the propagation axis). In a liquid, an ultrasonic wave induces the local displacement (e) of the particles, i.e., the oscillation around an equilibrium position. We will now consider a longitudinal wave obeying the central relationship (Eq. 3) which applies to the propagation of a one-dimensional linear wave ... 

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