Numerical study of strongly nonlinear acoustic waves, shock waves, and streaming caused by a harmonically pulsating sphere

1994 ◽  
Vol 6 (8) ◽  
pp. 2831-2844 ◽  
Author(s):  
Takeru Yano ◽  
Yoshinori Inoue
Keyword(s):  
Shock Waves ◽  
Acoustic Waves ◽  
Numerical Study ◽  
Strongly Nonlinear ◽  
Nonlinear Acoustic

THREE TIME-DOMAIN COMPUTATIONAL MODELS FOR QUASI-STANDING NONLINEAR ACOUSTIC WAVES, INCLUDING HEAT PRODUCTION

2006 ◽  
Vol 14 (02) ◽  
pp. 143-156 ◽  
Author(s):  
CHRISTIAN VANHILLE ◽  
CLEOFÉ CAMPOS-POZUELO
Keyword(s):  
Time Domain ◽  
Acoustic Waves ◽  
Computational Models ◽  
High Amplitude ◽  
Ultrasonic Waves ◽  
Physical Models ◽  
Industrial Processing ◽  
Strongly Nonlinear ◽  
Nonlinear Acoustic ◽  
The Time Domain

Applications of high-amplitude acoustic or ultrasonic waves in industrial processing require a good knowledge of the nonlinear pressure field, as well as the heat produced by the wave. In this article a new time-domain algorithm solving a second-order nonlinear wave equation written in Lagrangian coordinates and valid for any fluid is presented. The new model is compared with two others which were previously developed, corresponding to the two other possible physical approaches. This paper discusses the limits of application of every approach and the suitability of every one to model nonlinear acoustic waves in resonators. Conclusions about the applicability of the physical models are given. The time-domain character of the models allows the development of a new algorithm to calculate the temperature evolution inside a resonator due to acoustic losses. This algorithm is presented here and applied to strongly nonlinear waves for which the nonlinear attenuation is dominant. Several kinds of time functions for excitation can be considered in the models. The strongly nonlinear resonator response to a short pulsed signal is analyzed to show the efficiency of the time-domain numerical model.

Propagation of nonlinear acoustic waves in bimodular media with linear dissipation

Wave Motion ◽  
2013 ◽  
Vol 50 (2) ◽  
pp. 191-196 ◽  
Author(s):  
A. Radostin ◽  
V. Nazarov ◽  
S. Kiyashko
Keyword(s):  
Acoustic Waves ◽  
Nonlinear Acoustic ◽  
Bimodular Media

scholarly journals Atmospheric radiation boundary conditions for the Helmholtz equation

2018 ◽  
Vol 52 (3) ◽  
pp. 945-964 ◽  
Author(s):  
Hélène Barucq ◽  
Juliette Chabassier ◽  
Marc Duruflé ◽  
Laurent Gizon ◽  
Michael Leguèbe
Keyword(s):  
Boundary Conditions ◽  
Helmholtz Equation ◽  
Acoustic Waves ◽  
Numerical Study ◽  
Outgoing Wave ◽  
Atmospheric Radiation ◽  
Angle Of Incidence ◽  
Radiation Boundary Conditions ◽  
Radiation Boundary ◽  
Dirichlet To Neumann Map

This work offers some contributions to the numerical study of acoustic waves propagating in the Sun and its atmosphere. The main goal is to provide boundary conditions for outgoing waves in the solar atmosphere where it is assumed that the sound speed is constant and the density decays exponentially with radius. Outgoing waves are governed by a Dirichlet-to-Neumann map which is obtained from the factorization of the Helmholtz equation expressed in spherical coordinates. For the purpose of extending the outgoing wave equation to axisymmetric or 3D cases, different approximations are implemented by using the frequency and/or the angle of incidence as parameters of interest. This results in boundary conditions called atmospheric radiation boundary conditions (ARBC) which are tested in ideal and realistic configurations. These ARBCs deliver accurate results and reduce the computational burden by a factor of two in helioseismology applications.

Shock waves in sprays: numerical study of secondary atomization and experimental comparison

Shock Waves ◽  
2015 ◽  
Vol 26 (4) ◽  
pp. 403-415 ◽  
Author(s):  
A. Chauvin ◽  
E. Daniel ◽  
A. Chinnayya ◽  
J. Massoni ◽  
G. Jourdan
Keyword(s):  
Shock Waves ◽  
Numerical Study ◽  
Experimental Comparison ◽  
Secondary Atomization

Acoustic Resonance in an Axial Multistage Compressor Leading to Non-Synchronous Blade Vibration

2020 ◽  
Author(s):  
Anne-Lise Fiquet ◽  
Agathe Vercoutter ◽  
Nicolas Buffaz ◽  
Stéphane Aubert ◽  
Christoph Brandstetter
Keyword(s):  
Acoustic Waves ◽  
High Speed ◽  
Numerical Study ◽  
Acoustic Resonance ◽  
Structural Vibration ◽  
Wave Number ◽  
Blade Vibration ◽  
Acoustic Modes ◽  
Blade Vibrations ◽  
Circumferential Wave

Abstract Significant non-synchronous blade vibrations (NSV) have been observed in an experimental three-stage high-speed compressor at part-speed conditions. High amplitude acoustic modes, propagating around the circumference and originating in the highly loaded Stage-3 have been observed in coherence with the structural vibration mode. In order to understand the occurring phenomena, a detailed numerical study has been carried out to reproduce the mechanism. Unsteady full annulus RANS simulations of the whole setup have been performed using the solver elsA. The results revealed the development of propagating acoustic modes which are partially trapped in the annulus and are in resonance with an aerodynamic disturbance in Rotor-3. The aerodynamic disturbance is identified as an unsteady separation of the blade boundary layer in Rotor-3. The results indicate that the frequency and phase of the separation adapt to match those of the acoustic wave, and are therefore governed by acoustic propagation conditions. Furthermore, the simulations clearly show the modulation of the propagating wave with the rotor blades, leading to a change of circumferential wave numbers while passing the blade row. To analyze if the effect is self-induced by the blade vibration, a noncoherent structural mode has been imposed in the simulations. Even at high vibration amplitude the formerly observed acoustic mode did not change its circumferential wave number. This phenomenon is highly relevant to modern compressor designs, since the appearance of the axially propagating acoustic waves can excite blade vibrations if they coincide with a structural eigenmode, as observed in the presented experiments.

Amplification of energy flux of nonlinear acoustic waves in a gas-filled tube under an axial temperature gradient

2002 ◽  
Vol 456 ◽  
pp. 377-409 ◽  
Author(s):  
N. SUGIMOTO ◽  
K. TSUJIMOTO
Keyword(s):  
Boundary Layer ◽  
Temperature Gradient ◽  
Energy Flux ◽  
Acoustic Waves ◽  
Wave Equations ◽  
Main Flow ◽  
Nonlinear Wave Equations ◽  
Axial Temperature Gradient ◽  
Axial Temperature ◽  
Nonlinear Acoustic

This paper considers nonlinear acoustic waves propagating unidirectionally in a gas-filled tube under an axial temperature gradient, and examines whether the energy flux of the waves can be amplified by thermoacoustic effects. An array of Helmholtz resonators is connected to the tube axially to avoid shock formation which would otherwise give rise to nonlinear damping of the energy flux. The amplification is expected to be caused by action of the boundary layer doing reverse work, in the presence of the temperature gradient, on the acoustic main flow outside the boundary layer. By the linear theory, the velocity at the edge of the boundary layer is given in terms of the fractional derivatives of the axial velocity of the gas in the acoustic main flow. It is clearly seen how the temperature gradient controls the velocity at the edge. The velocity is almost in phase with the heat flux into the boundary layer from the wall. With effects of both the boundary layer and the array of resonators taken into account, nonlinear wave equations for unidirectional propagation in the tube are derived. Assuming a constant temperature gradient along the tube, the evolution of compression pulses is solved numerically by imposing the initial profiles of both an acoustic solitary wave and of a square pulse. It is revealed that when a positive gradient is imposed, the excess pressure decreases while the particle velocity increases and that the total energy flux can indeed be amplified if the gradient is suitable.

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