Sound attenuation coefficients

In each case the attenuation of sound can be formally represented by defining a complex wavenumber, where the sound attenuation coefficient is the imaginary part of the wavenumber. The complex wavenumber also leads to the definition of a complex sound speed and a complex dynamic elastic modulus. 

Eg.8 has the same form as the relation between the (real) elastic modulus and sound speed in a lossless medium. From Eqs.6-8 it follows that the sound attenuation coefficient is related to the complex elastic modulus,... 

Density (pj,), bulk modulus (K, ), viscosity (r ), sound velocity (Vp), sound attenuation coefficient (a) and electrical resistivity (Rj.) of sea water depend on salinity, temperature and pressure. Table 2A-2 summarizes their values at laboratory... 

Above about 0.5 GHz, Brillouin scattering provides an elegant technique of measuring phonon mean free paths (which are inversely proportional to the sound attenuation coefficient) by evaluating the width of the Brillouin lines [53]. However, as a result of finite spectrometer resolution and contrast, this method is limited to aerogel densities above 180 kg/m. ... 

The transport coefficients that we want to investigate are the shear viscosity, the thermal conductivity, and the sound attenuation coefficient. It has been shown recently that the shear viscosity can be expressed directly in terms of certain matrix elements of... 

The sound attenuation coefficient, denoted p and expressed in m , is dependent on the physical properties of the medium as follows ... 

From equations 17-19 it follows that the sound attenuation coefficient is related to the complex elastic modulus,... 

The sound attenuation coefficient, a, is k dependent. As already mentioned, light scattering is especially useful in the study of systems where long lived hydrodynamic modes occur with decay times proportional to some power of the wavelength. Here, the conservation of energy and momentum in a... 

By means of this thermodynamic model the internal friction for an isotropic ferromagnet near Tq was calculated by Belov et al. (1960) and Peqioular (1965). The internal friction characterizes the damping of the sample s sound vibrations with time and is defined as a ratio of the mechanical energy dissipated over a period of time to the fill mechanical energy of the sample. It is related to the sound attenuation coefficient as... 

The width, r, (half width at half maximum) of the Brillouin lines is proportional to the sound attenuation coefficient. 

Here, we briefly summarize the results for the dynamic structure factor. The dynamic sfiucture factor exhibits three peaks, a central Rayleigh peak caused by the thermal diffusion, and two symmetrically placed Brillouin peaks caused by sound. The width of the central peak is determined by the thermal diflfusivity, Dj, while that of the two Brillouin peaks is related to the sound attenuation coefficient, r. For the SRD algorithm [57],... 

Note that in two-dimensions, the sound attenuation coefficient for a SRD fluid has the same functional dependence on Dt and v = as an isotropic fluid with... 

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