scholarly journals On the forms of nonlinear propagation of high-frequency perturbation in a thermal relaxing gas-liquid mixture.

2010 ◽  
Vol 63 (3) ◽  
pp. 66-75
Author(s):  
G.G. Ohanyan
Keyword(s):  
High Frequency ◽  
Liquid Mixture ◽  
Nonlinear Propagation ◽  
Relaxing Gas

Nonlinear propagation of high-frequency plasma waves in a magnetized plasma

1977 ◽  
Vol 18 (2) ◽  
pp. 249-256 ◽  
Author(s):  
P. K. Shukla
Keyword(s):  
High Frequency ◽  
Nonlinear Effects ◽  
Plasma Waves ◽  
Electron Plasma ◽  
Magnetized Plasma ◽  
Nonlinear Propagation ◽  
Arbitrary Angle ◽  
High Frequency Plasma ◽  
Frequency Plasma ◽  
Density Perturbations

We study nonlinear effects associated with large amplitude electron plasma waves propagating at an arbitrary angle to the external magnetic field. It is shown that the nonlinear coupling of high-frequency plasma waves with static density perturbations leads to a convective instability. The growth length of the latter is obtained. The evolution of the wave electric field is also investigated.

scholarly journals Construction of an Omnidirectional Parametric Loudspeaker Consisting in a Spherical Distribution of Ultrasound Transducers

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4317 ◽  
Author(s):  
Marc Arnela ◽  
Oriol Guasch ◽  
Patricia Sánchez-Martín ◽  
Joan Camps ◽  
Rosa Alsina-Pagès ◽  
...  
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Nonlinear Propagation ◽  
Ultrasound Transducers ◽  
Frequency Range ◽  
Carrier Wave ◽  
Sound Sources ◽  
Low Frequencies ◽  
Structural Assembly ◽  
Chamber Measurements

Omnidirectional sound sources are needed to perform a large variety of tests in acoustics. Typically, they consist of conventional speaker drivers arranged in a dodecahedron. However, the directivity of the speaker drivers sharpens with frequency, which induces an intense decrease of the sound pressure levels at the edges of the dodechaedron. In this work, the problem is mitigated by building an Omnidirectional Parametric Loudspeaker (OPL), which contains hundreds of small ultrasound transducers set on a sphere. Each transducer emits an ultrasonic carrier wave modulated by an audible signal. Thanks to nonlinear propagation, the air itself demodulates the signal bringing it back to the audible range. The construction of an OPL prototype is challenging. The structure has been built by 3D-printing a set of pieces that conform to the sphere. Each piece contains the exact location of the transducers, which are aligned in parallels to facilitate the structural assembly and the wiring. The performance of the OPL has been tested in an anechoic chamber. Measurements show that the OPL has a good omnidirectional behavior for most frequencies. It clearly improves the directivity of dodechaedral sources in the high frequency range, but performs worse at low frequencies.

Nonlinear Influence of Sound on the Vibrational Energy of Molecules in a Relaxing Gas

2012 ◽  
Vol 37 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Anna Perelomova
Keyword(s):  
High Frequency ◽  
Degrees Of Freedom ◽  
Vibrational Energy ◽  
Acoustic Energy ◽  
Acoustic Source ◽  
Weakly Nonlinear ◽  
Dispersive Flow ◽  
Nonlinear Character ◽  
Nonlinear Acoustic ◽  
Relaxing Gas

AbstractDynamics of a weakly nonlinear and weakly dispersive flow of a gas where molecular vibrational relaxation takes place is studied. Variations in the vibrational energy in the field of intense sound is considered. These variations are caused by a nonlinear transfer of the acoustic energy into energy of vibrational degrees of freedom in a relaxing gas. The final dynamic equation which describes this is instantaneous, it includes a quadratic nonlinear acoustic source reflecting the nonlinear character of interaction of high-frequency acoustic and non-acoustic motions in a gas. All types of sound, periodic or aperiodic, may serve as an acoustic source. Some conclusions about temporal behavior of the vibrational mode caused by periodic and aperiodic sounds are made.

ASYMPTOTICAL SOLUTIONS FOR A VIBRATIONALLY RELAXING GAS

2009 ◽  
Vol 14 (4) ◽  
pp. 423-434 ◽  
Author(s):  
Rajan Arora
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Symmetric Flow ◽  
Van Der Waals Equation ◽  
One Dimensional ◽  
Resonant Wave ◽  
Cylindrically Symmetric ◽  
Geometrical Acoustics ◽  
Basic Equations ◽  
Relaxing Gas

Using the weakly non‐linear geometrical acoustics theory, we obtain the small amplitude high frequency asymptotic solution to the basic equations governing one dimensional unsteady planar, spherically and cylindrically symmetric flow in a vibrationally relaxing gas with Van der Waals equation of state. The transport equations for the amplitudes of resonantly interacting waves are derived. The evolutionary behavior of non‐resonant wave modes culminating into shock waves is also studied.

Propagation of modulated nonlinear waves in a relaxing gas-liquid mixture

1980 ◽  
Vol 15 (1) ◽  
pp. 108-116
Author(s):  
A. G. Bagdoev ◽  
G. G. Oganyan
Keyword(s):  
Nonlinear Waves ◽  
Liquid Mixture ◽  
Relaxing Gas

Numerical analysis of the nonlinear propagation of plane periodic waves in a relaxing gas

1980 ◽  
Vol 99 (2) ◽  
pp. 343-364 ◽  
Author(s):  
I. S. Southern ◽  
N. H. Johannesen
Keyword(s):  
Heat Conduction ◽  
Acoustic Streaming ◽  
Approximate Solutions ◽  
Nonlinear Propagation ◽  
Periodic Waves ◽  
Secondary Effects ◽  
Progressive Wave ◽  
Convective Effect ◽  
The Waves ◽  
Relaxing Gas

The waves propagating from an oscillating plane piston into a vibrationally relaxing gas are calculated by an exact numerical method ignoring viscosity and heat conduction. Secondary effects due to the starting of the piston from rest and to acoustic streaming can be eliminated from the calculated flows, leaving a truly periodic progressive wave which can be analysed and compared with approximate solutions. It is found that for moderate amplitude waves nonlinearity is only important as a convective effect which produces higher harmonics, whereas dissipation is adequately described by linear theory.

Kinetic theory of transverse plasmons in pair plasmas

2010 ◽  
Vol 77 (2) ◽  
pp. 145-153 ◽  
Author(s):  
S. Q. LIU ◽  
Y. LIU
Keyword(s):  
High Frequency ◽  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Ponderomotive Force ◽  
Nonlinear Propagation ◽  
Governing Equations ◽  
Filamentary Structure ◽  
Wave Fields ◽  
Propagation Behavior ◽  
Spatially Inhomogeneous

AbstractA set of nonlinear governing equations for interactions of transverse plasmons with pair plasmas is derived from Vlasov–Maxwell equations. It is shown the ponderomotive force induced by high-frequency transverse plasmons will expel the pair particles away, resulting in the formation of density cavity in which transverse plasmons are trapped. Numerical results show the envelope of wave fields will collapse and break into a filamentary structure due to the spatially inhomogeneous growth rate. The results obtained would be useful for understanding the nonlinear propagation behavior of intense electromagnetic waves in pair plasmas.

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