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Infrasound, sometimes referred to as low frequency sound or subsonic, describes sound waves with a frequency below the lower limit of human audibility ...
Sound waves propagating through a liquid at ultrasonic frequencies have wavelengths many times longer than the molecular dimensions or the bond length between atoms in the molecule. Therefore, the sound wave cannot directly affect the vibrational energy of the bond, and can therefore not directly increase the internal energy of a molecule.
The simplest theory to predict the behaviour of detonations in gases is known as the Chapman–Jouguet (CJ) condition, developed around the turn of the 20th century. This theory, described by a relatively simple set of algebraic equations, models the detonation as a propagating shock wave accompanied by exothermic heat release.
As explained above, a deflagration is a subsonic reaction, whereas a detonation is a supersonic (greater than the sound speed of the material) reaction. Distinguishing between a deflagration or a detonation can be difficult to impossible to the casual observer.
Sound propagates as mechanical vibration waves of pressure and displacement, in air or other substances. [5] In general, frequency components of a sound determine its "color", its timbre . When speaking about the frequency (in singular) of a sound, it means the property that most determines its pitch . [ 6 ]
However, this range is an average and will slightly change from individual to individual. Sound waves that have frequencies below 16 Hz are called infrasoniciis and those above 20 kHz are called ultrasonic. Sound is a mechanical wave and as such consists physically in oscillatory elastic compression and in oscillatory displacement of a fluid.
In more detail (in the ZND model) in the frame of the leading shock of the detonation wave, gases enter at supersonic velocity and are compressed through the shock to a high-density, subsonic flow. This sudden change in pressure initiates the chemical (or sometimes, as in steam explosions, physical) energy release. The energy release re ...
This falls within the domain of physical acoustics. In fluids, sound propagates primarily as a pressure wave. In solids, mechanical waves can take many forms including longitudinal waves, transverse waves and surface waves. Acoustics looks first at the pressure levels and frequencies in the sound wave and how the wave interacts with the ...