scholarly journals Velocity and Absorption Coefficient of Sound Waves in Classical Gases

2020 ◽  
Vol 65 (3) ◽  
pp. 217
Author(s):  
A. G. Magner ◽  
M. I. Gorenstein ◽  
U. V. Grygoriev
Keyword(s):  
Absorption Coefficient ◽  
Sound Velocity ◽  
Linear Response Theory ◽  
Boltzmann Kinetic Equation ◽  
Particle Collision ◽  
Sound Waves ◽  
Relaxation Time Approximation ◽  
Plane Sound ◽  
Periodic External Field ◽  
Theoretical Results

The velocity and absorption coefficient of plane sound waves in classical gases are obtained by solving the Boltzmann kinetic equation. This is done within the linear response theory as a reaction of the single-particle distribution function to a periodic external field. The nonperturbative dispersion equation is derived in the relaxation time approximation and solved numerically. The obtained theoretical results demonstrate an universal dependence of the sound velocity and scaled absorption coefficient on the variable wт , where w is the sound frequency, and т−1 is the particle collision frequency. In the region of wт ∼ 1, a transition from the frequent- to rare-collision regime takes place. The sound velocity increases sharply, and the scaled absorption coefficient has a maximum – both theoretical findings are in agreement with the data.

Plane Sound Waves

2020 ◽  
pp. 43-57
Author(s):  
Anatoly Kistovich ◽  
Konstantin Pokazeev ◽  
Tatiana Chaplina
Keyword(s):  
Sound Waves ◽  
Plane Sound

scholarly journals Non-Wovens as Sound Reducers

2018 ◽  
Vol 55 (2) ◽  
pp. 64-76
Author(s):  
D. Belakova ◽  
A. Seile ◽  
S. Kukle ◽  
T. Plamus
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Material Structure ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

Estimation and experimental test of the sound-absorption coefficient of a pin-holder structure (Case of sound waves incidence upon the side surfaces of a group of cylinders)

2021 ◽  
Vol 263 (3) ◽  
pp. 3714-3719
Author(s):  
Takamasa Sato ◽  
Shuichi Sakamoto ◽  
Isami Nitta ◽  
Shunsuke Unai ◽  
Takunari Isobe ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Propagation Constant ◽  
Characteristic Impedance ◽  
Physical Property ◽  
Sound Absorption Coefficient ◽  
Accurate Estimation ◽  
Sound Waves ◽  
Acoustic Characteristics ◽  
Measuring Tube

In this study, we conducted theoretical analyses and experiments related to the acoustic characteristics of the situation where sound waves are incident upon the side surfaces of a group of cylinders forming a pin-holder structure. The sound-absorption coefficient, entering its clearance between cylinders through the geometrical dimension of the clearance or the physical property of gas, was calculated. In the analytical model, the gap part of the pin-holder structure was divided into elements and approximated as a gap surrounded by two parallel planes. The characteristic impedance and propagation constant of the approximate gap were obtained and treated as one-dimensional transfer matrices; the sound-absorption coefficient was then calculated using the transfer-matrix method. The calculated value was compared to that obtained in an experiment with a sample prepared using a 3D printer; the sound-absorption coefficient was measured using a 2-microphone impedance-measuring tube. We attempted to make a simple yet accurate estimation of sound-absorption coefficient using these procedures. Our theoretical values displayed a similar tendency to that obtained by experiment.

PLANE SOUND WAVES OF SMALL AMPLITUDE IN A GAS-DUST MIXTURE WITH POLYDISPERSE PARTICLES

2021 ◽  
Vol 62 (4) ◽  
pp. 663-672
Author(s):  
T. V. Markelova ◽  
M. S. Arendarenko ◽  
E. A. Isaenko ◽  
O. P. Stoyanovskaya
Keyword(s):  
Small Amplitude ◽  
Sound Waves ◽  
Plane Sound ◽  
Polydisperse Particles

Plane Sound Waves of Low Amplitude in a Gas-Dust Environment with Polydispersed Particles

2021 ◽  
Vol 62 (4) ◽  
pp. 158-168
Author(s):  
T. V. Markelova ◽  
M. S. Arendarenko ◽  
E. A. Isaenko ◽  
O. P. Stoyanovskaya
Keyword(s):  
Sound Waves ◽  
Plane Sound ◽  
Low Amplitude

Plane Sound Waves on Boundaries

1983 ◽  
pp. 23-45
Author(s):  
Josef Krautkrämer ◽  
Herbert Krautkrämer
Keyword(s):  
Sound Waves ◽  
Plane Sound

Dynamic Fields and Response Properties

2020 ◽  
pp. 473-554
Author(s):  
Jochen Autschbach
Keyword(s):  
Absorption Coefficient ◽  
Linear Response ◽  
Optical Rotation ◽  
Polarized Light ◽  
Linear Response Theory ◽  
Time Dependent ◽  
Electronic Transitions ◽  
Orbital Theory ◽  
Response Properties ◽  
Set Up

It is shown how electronic transitions can be induced by the interaction with an electromagnetic wave of a suitable frequency. The rate of a transition between two electronic states induced by a time-dependent field is derived. The transition rate expression is used to calculate the absorption coefficient due to electronic transitions. The differential absorption coefficient for left and right circular polarized light is specific to chiral molecules and has different signs for a pair of enantiomers. The discussion then shifts to general functions describing the response of an atom or molecule to an external. The ideas developed thus far are then applied to the dynamic polarizability, molecular linear response functions in general, and the optical rotation. Linear response theory is set up within time-dependent molecular orbital theory. The Chapter concludes with a discussion of non-linear response properties and two-photon absorption.

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