On the propagation of disturbances from moving sources

AbstractThe concept of the Green's vibrational function given in an earlier paper by the author is used to obtain a general expression for the disturbance from a point source. The potential due to transient sources of sound moving with subsonic and supersonic velocities is derived from this. It is found that the Doppler effect for a supersonic source differs from that for a subsonic source. In the former case it is found that two frequencies are heard simultaneously from a source emitting a note of one frequency.The theory is applied to determine some solutions of the two dimensional equation of supersonic, irrotational compressible flow, corresponding to the flow around an aerofoil taking into consideration the entropy changes at the shock wave.

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Thermal waves emitted by moving sources and the Doppler effect

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2021.121098 ◽

2021 ◽

Vol 176 ◽

pp. 121098

Author(s):

Roberto Li Voti ◽

Mario Bertolotti

Keyword(s):

Doppler Effect ◽

Thermal Waves ◽

Moving Sources ◽

The Doppler Effect

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Non-stationary compressible flow in ducts with varying cross-section

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1243/0954410981532405 ◽

1998 ◽

Vol 212 (4) ◽

pp. 225-243 ◽

Cited By ~ 6

Author(s):

O Igra ◽

L Wang ◽

J Falcovitz

Keyword(s):

Shock Wave ◽

Comparative Study ◽

Rarefaction Wave ◽

Compressible Flow ◽

Cross Section ◽

Constant Cross Section ◽

Two Dimensional ◽

Duct Flow ◽

One Dimensional ◽

Flow Approximation

A comparative study of the interaction of shock wave or rarefaction wave with a converging duct separating long constant cross-section segments is presented. Quasi-one-dimensional computations are compared with fully two-dimensional computations. It is observed that in some cases the two-dimensional results approach the respective one-dimensional approximations over long times, while in other cases the two-dimensional computed flow is genuinely two-dimensional and cannot be reduced to a one-dimensional equivalent. In the latter cases, significant errors are incurred by analysing the flow using the quasi-one- dimensional duct flow approximation.

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Possibilities of ultrasound methods in the diagnosis of decompression sickness

Marine Medicine ◽

10.22328/2413-5747-2021-7-4-75-83 ◽

2022 ◽

Vol 7 (4) ◽

pp. 75-83

Author(s):

D. P. Zverev ◽

S. A. Bychkov ◽

A. A. Myasnikov ◽

A. M. Yarkov ◽

A. B. Khaustov ◽

...

Keyword(s):

Doppler Effect ◽

Ultrasound Examination ◽

Decompression Sickness ◽

Two Dimensional ◽

Right Heart ◽

Gas Formation ◽

The Doppler Effect ◽

Dimensional Echocardiography ◽

The Right ◽

Two Dimensional Echocardiography

Aim of the work: to conduct a comparative analysis of methods of ultrasound examination of the right heart with audio and visual indication of intravascular decompression gas formation in divers after diving.Materials and methods. An examination of the right heart in divers after 152 man-descents was carried out. Intravascular decompression gas production was assessed by ultrasound using sound location based on the Doppler effect and transthoracic two-dimensional echocardiography.Results and discussion. Both methods make it possible to determine intravascular decompression gas formation after a diving descent, correlate with the clinical picture of acute decompression sickness and should be used in the medical support of diving descents. At the same time, the method of ultrasound examination based on transthoracic two-dimensional echocardiography turned out to be more sensitive in determining gas bubbles in the right heart as compared to auditory location with the Doppler effect.

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Sound generation by a two-dimensional circular cylinder in a uniform flow

Journal of Fluid Mechanics ◽

10.1017/s0022112002002124 ◽

2002 ◽

Vol 471 ◽

pp. 285-314 ◽

Cited By ~ 175

Author(s):

OSAMU INOUE ◽

NOZOMU HATAKEYAMA

Keyword(s):

Circular Cylinder ◽

Vortex Shedding ◽

Doppler Effect ◽

Sound Pressure ◽

Pressure Pulse ◽

Positive Pressure ◽

Pressure Waves ◽

Two Dimensional ◽

The Doppler Effect ◽

Mach Numbers

The sound generated by a circular cylinder in a flow at low Mach numbers is investigated by direct solution of the two-dimensional unsteady compressible Navier–Stokes equations. Results show that sound pressure waves are generated primarily by vortex shedding from the cylinder surface into its wake. When a vortex is shed from one side of the cylinder, a negative pressure pulse is generated from that side whereas a positive pressure pulse is generated from the other side; alternate vortex shedding from the upper and lower sides of the cylinder produces negative and positive pulses alternately and thus produces sound pressure waves on both sides. The dipolar nature of the generated sound is confirmed; lift dipole dominates the sound field. The Doppler effect is shown to play an important role at finite Mach numbers. The direct solutions are also compared with the solutions obtained by Curle's acoustic analogy. The results show that Curle's solution describes well not only the generation mechanism of the sound but also the propagation process if we take the Doppler effect into consideration.

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The formation of gas hydrates under shock wave impact on the bubble media (two-dimensional case)

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2010.1.007 ◽

2010 ◽

Vol 7 ◽

pp. 90-97

Author(s):

M.N. Galimzianov ◽

I.A. Chiglintsev ◽

U.O. Agisheva ◽

V.A. Buzina

Keyword(s):

Shock Wave ◽

Gas Hydrates ◽

Hydrate Formation ◽

Dimensional Case ◽

Two Dimensional ◽

Wave Impact ◽

Bubble Liquid ◽

One Dimensional ◽

Bubble Media ◽

Main Factors

Formation of gas hydrates under shock wave impact on bubble media (two-dimensional case) The dynamics of plane one-dimensional shock waves applied to the available experimental data for the water–freon media is studied on the base of the theoretical model of the bubble liquid improved with taking into account possible hydrate formation. The scheme of accounting of the bubble crushing in a shock wave that is one of the main factors in the hydrate formation intensification with increasing shock wave amplitude is proposed.

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Features of spatial shock-wave flows in vapor-gas-liquid mixtures

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2014.1.005 ◽

2014 ◽

Vol 10 ◽

pp. 27-31

Author(s):

R.Kh. Bolotnova ◽

U.O. Agisheva ◽

V.A. Buzina

Keyword(s):

Shock Wave ◽

High Pressure ◽

Shock Waves ◽

Liquid Mixture ◽

Liquid Mixtures ◽

Pressure Vessels ◽

Water Mixture ◽

Two Dimensional ◽

Nonstationary Processes ◽

Two Phase

The two-phase model of vapor-gas-liquid medium in axisymmetric two-dimensional formulation, taking into account vaporization is constructed. The nonstationary processes of boiling vapor-water mixture outflow from high-pressure vessels as a result of depressurization are studied. The problems of shock waves action on filled by gas-liquid mixture volumes are solved.

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On Comparison of Homotopy Analysis Method and Finite Difference Method for Two Dimensional Steady Compressible Flow with Pressure Gradients

International Journal of Applied and Computational Mathematics ◽

10.1007/s40819-021-00952-4 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Mahantesh M. Nandeppanavar ◽

R. Madhusudhan ◽

M. C. Kemparaju ◽

R. Latha

Keyword(s):

Finite Difference ◽

Finite Difference Method ◽

Compressible Flow ◽

Homotopy Analysis Method ◽

Difference Method ◽

Pressure Gradients ◽

Two Dimensional ◽

Analysis Method ◽

Homotopy Analysis

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Study on X-ray Induced Two-Dimensional Thermal Shock Waves in Carbon/Phenolic

Materials ◽

10.3390/ma14133553 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3553

Author(s):

Dengwang Wang ◽

Yong Gao ◽

Sheng Wang ◽

Jie Wang ◽

Haipeng Li

Keyword(s):

Numerical Simulation ◽

Shock Wave ◽

Wave Propagation ◽

Thermal Shock ◽

Anisotropic Material ◽

Energy Deposition ◽

X Rays ◽

Two Dimensional ◽

X Ray ◽

Deposition Depth

Carbon/Phenolic (C/P), a typical anisotropic material, is an important component of aerospace and often used to protect the thermodynamic effects of strong X-ray radiation. In this paper, we establish the anisotropic elastic-plastic constitutive model, which is embedded in the in-house code “RAMA” to simulate a two-dimensional thermal shock wave induced by X-ray. Then, we compare the numerical simulation results with the thermal shock wave stress generated by the same strong current electron beam via experiment to verify the correctness of the numerical simulation. Subsequently, we discuss and analyze the rules of thermal shock wave propagation in C/P material by further numerical simulation. The results reveal that the thermal shock wave represents different shapes and mechanisms by the radiation of 1 keV and 3 keV X-rays. The vaporization recoil phenomenon appears as a compression wave under 1 keV X-ray irradiation, and X-ray penetration is caused by thermal deformation under 3 keV X-ray irradiation. The thermal shock wave propagation exhibits two-dimensional characteristics, the energy deposition of 1 keV and 3 keV both decays exponentially, the energy deposition of 1 keV-peak soft X-ray is high, and the deposition depth is shallow, while the energy deposition of 3 keV-peak hard X-ray is low, and the deposition depth is deep. RAMA can successfully realize two-dimensional orthotropic elastoplastic constitutive relation, the corresponding program was designed and checked, and the calculation results for inspection are consistent with the theory. This study has great significance in the evaluation of anisotropic material protection under the radiation of intense X-rays.

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