Heat Pulse Propagation in Pure Sodium Fluoride at Low Temperatures From Ballistic to Diffusive Conduction

2011 ◽  
Author(s):  
Yanbao Ma
Keyword(s):  
Pulse Propagation ◽  
Arrival Time ◽  
Relaxation Times ◽  
Heat Pulse ◽  
Second Sound ◽  
Sound Waves ◽  
Scattering Process ◽  
Transverse Waves ◽  
Longitudinal Waves ◽  
Phase Velocities

In this paper, heat pulse propagation in pure NaF at low temperature is studied by using hydrodynamic equations of a weakly interacting phonon gas. The observed longitudinal waves, transverse waves, second sound waves, and diffusive waveforms from the experiments conducted in early 1970s are numerically reconstructed. In the numerical simulations, the phase velocities of the longitudinal waves and the transverse waves are based on the experimental results, while two relaxation times for normal scattering process (τN) and resistive scattering process (τR) respectively are adjusted to fit the arrival time of second sound or to fit the observed waveforms observed in the experiments. The waveforms based on numerical results can fit the observed waveforms quite well. It is elucidated how heat pulse is transmitted by different waves in the dielectric crystal from ballistic to diffusive regions.

A New Ballistic-Diffusive Model for Heat Pulse Propagation

2012 ◽  
Author(s):  
Yanbao Ma
Keyword(s):  
Heat Flux ◽  
Pulse Propagation ◽  
Dielectric Materials ◽  
Heat Pulse ◽  
Second Sound ◽  
Sound Waves ◽  
Transverse Waves ◽  
Longitudinal Waves ◽  
Diffusive Model ◽  
Diffusive Part

In this paper, we reported a new ballistic-diffusive model for heat pulse propagation in dielectric materials. The internal energy and heat flux are split into ballistic part originating from the boundaries and diffusive part originating from inside medium. The ballistic part is modeled based on analytical solutions while the diffusive part is described by Guyer-Krumhansl equations. To validate this model, heat pulse propagation in pure NaF at low temperature is studied. The observed longitudinal waves, transverse waves, second sound waves, and diffusive waveforms from the experiments conducted in early 1970s are numerically reconstructed. There is qualitative agreement between numerical results and experimental observation.

Heat pulse propagation by second sound in dielectric crystals

1997 ◽  
Vol 9 (15) ◽  
pp. 3117-3127 ◽  
Author(s):  
A Valenti ◽  
M Torrisi ◽  
G Lebon
Keyword(s):  
Pulse Propagation ◽  
Heat Pulse ◽  
Second Sound

Non-Local Model Analysis of Heat Pulse Propagation and Simulation of Experiments in W7-AS

1999 ◽  
Vol 68 (2) ◽  
pp. 478-486 ◽  
Author(s):  
Takuya Iwasaki ◽  
Sanae-I. Itoh ◽  
Masatoshi Yagi ◽  
Kimitaka Itoh ◽  
Ulich Stroth
Keyword(s):  
Pulse Propagation ◽  
Model Analysis ◽  
Heat Pulse ◽  
Local Model ◽  
Non Local

scholarly journals Amplitudes of P, PP, and S and magnitude of shallow earthquakes*

1945 ◽  
Vol 35 (2) ◽  
pp. 57-69
Author(s):  
B. Gutenberg
Keyword(s):  
Absorption Coefficient ◽  
Shallow Earthquake ◽  
Transverse Waves ◽  
Longitudinal Waves ◽  
Longitudinal And Transverse Waves ◽  
The Core ◽  
The Earth ◽  
Shallow Earthquakes

Summary It is found that the absorption coefficient for longitudinal and transverse waves in the mantle of the earth as well as for longitudinal waves through the core is 0.00012 per km. In the average shallow earthquake about equal amounts of energy go into longitudinal and transverse waves. Equation (18), together with tables 2 and 4, permits the calculation of the magnitude of a shallow earthquake from the amplitudes of P, PP, or S.

scholarly journals Specificity of the second sound standing waves behavior in a medium with nanoparticles

2021 ◽  
Vol 2056 (1) ◽  
pp. 012040
Author(s):  
A A Esina ◽  
V B Efimov
Keyword(s):  
Normal Component ◽  
Experimental Studies ◽  
Standing Waves ◽  
Second Sound ◽  
Sound Waves ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Significant Attenuation ◽  
Waves Propagation

Abstract The experimental studies of the second sound waves propagation in a resonator with a deuterium-helium gel were carried out. The latest experimental results, combined with those obtained in earlier experiments, have shown that the propagation of the second sound waves in gels leads to their significant attenuation and a decrease in the propagation velocity. This behavior differs from the case of the propagation of the sound waves of a two-component system with a strongly slow normal component and may indicate changes in the properties of superfluidity under confined geometry conditions.

Non-planar and Non-linear Second Sound Waves in He II

2000 ◽  
Vol 17 (1) ◽  
pp. 43-45 ◽  
Author(s):  
Peng Zhang ◽  
Seiji Kimura ◽  
Masahide Murakami ◽  
Ru-zhu Wang
Keyword(s):  
Second Sound ◽  
Sound Waves ◽  
Non Linear

Effects of director rotation relaxation on viscoelastic wave dispersion in nematic elastomer beams

2018 ◽  
Vol 24 (4) ◽  
pp. 1103-1115 ◽  
Author(s):  
Dong Zhao ◽  
Ying Liu
Keyword(s):  
Wave Motion ◽  
Relaxation Times ◽  
Low Frequency ◽  
Wave Dispersion ◽  
Frequency Limit ◽  
Anisotropic Parameter ◽  
Acoustic Design ◽  
Phase Velocities ◽  
Nematic Elastomer ◽  
Viscoelastic Wave

In this paper, the transverse wave dispersion in a nematic elastomer (NE) Timoshenko beam is studied by considering anisotropy and viscoelasticity of NEs in the low frequency limit. Firstly, the characteristic equations of wave motion in an NE beam are derived, and then numerically solved to obtain the corresponding phase velocities and attenuation factors. The influences of anisotropic parameter, director rotation and rubber relaxation times on the wave dispersion in an NE beam are discussed. Results show that unlike the situation in general isotropic viscoelastic beam, non-classical viscoelastic wave dispersion is found in NE beams. Geometric dispersion is restrained with the vanishing of cut-off frequencies for shear waves due to director rotation relaxation of NEs. This unique property promises prospective applications of NE beams in optic or acoustic design.

Identification of the Model of Nonlinear Elasticity in Dynamic Experiments

2021 ◽  
pp. 2150025
Author(s):  
Marina Sokolova ◽  
Yuri Astapov ◽  
Dmitrii Khristich
Keyword(s):  
Deformable Body ◽  
Polyamide 6 ◽  
Preliminary Deformation ◽  
Transverse Waves ◽  
Wave Velocities ◽  
Phase Velocities ◽  
Dynamic Methods ◽  
Dynamic Experiments ◽  
Effective Phase ◽  
Nonlinearly Elastic

Dynamic methods for identifying a model of a nonlinearly elastic deformable body are considered. By the effective phase velocities of longitudinal and transverse waves propagating along and across the axis of the compressed bar, it is possible to determine five elastic constants of the second and third orders included in the model relations. Calculation formulae are obtained and an example of determining the dependence of phase velocities on the preliminary deformation for polyamide 6 is given. The influence of preliminary deformations on polar diagrams of wave velocities is investigated.

Sign in / Sign up

Export Citation Format

Share Document