Dissipation factor acoustic

This definition is special to acoustics and is different from the usage in radiation, where the absorption factor corresponds to the acoustic dissipation factor. 

In the context of resonant acoustic devices, Q =fiJBW, where fn is the resonant frequency and BW is the bandwidth it can equivalently be defuied as loU Pj, where o> is the angular frequency. Up is the peak total energy present in the device, and is the power dissipated by the device. For resonant systems, BW is the range of frequencies over which the reflected power is within 3 dB (a factor of two) of its minimum value, attained at fit, for non-resonant systems (e.g., delay lines), BW is the range of iiequencies over which the transmitted power is within a factor of two of its maximum value. 

Wall thickness Channel width Acoustic velocity Friction coefficient Conductance Capillary number Discharge coefficient Drag coefficient Diameter Diameter Dean number Deformation rate tensor components Elastic modulus Energy dissipation rate Eotvos number Fanning friction factor Vortex shedding frequency Force... 

The kinetic ener produced by the absorption of a modulated beam of light in a resonator causes the excitation of acoustic normal modes in the cavity. The rimple theoretical approach considered in this section is that of a lossless gas in a rigid container with perfectly insulating walls. This simple model yields reasonable values for the eigenfrequencies of the resonator. However, for an accurate description of experimentally determined resonance frequencies and the corresponding Q factors, dissipation effects, deviations of the cavity from the ideal geometry, etc. must be taken into account. The advances made in recent years in an understanding of these loss mechanisms will be discussed in the next section. 

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