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1
Content available remote

Acoustic heating produced in the thermoviscous flow of a Bingham plastic

100%
Perelomova A.
Open Physics
|
2011
|
vol. 9
|
issue 1
138-145
EN
This study is devoted to the instantaneous acoustic heating of a Bingham plastic. The model of the Bingham plastic’s viscous stress tensor includes the yield stress along with the shear viscosity, which differentiates a Bingham plastic from a viscous Newtonian fluid. A special linear combination of the conservation equations in differential form makes it possible to reduce all acoustic terms in the linear part of of the final equation governing acoustic heating, and to retain those belonging to the thermal mode. The nonlinear terms of the final equation are a result of interaction between sounds and the thermal mode. In the field of intense sound, the resulting nonlinear acoustic terms form a driving force for the heating. The final governing dynamic equation of the thermal mode is valid in a weakly nonlinear flow. It is instantaneous, and does not imply that sounds be periodic. The equations governing the dynamics of both sounds and the thermal mode depend on sign of the shear rate. An example of the propagation of a bipolar initially acoustic pulse and the evolution of the heating induced by it is illustrated and discussed.
2
Content available remote

Hysteresis curves and loops for harmonic and impulse perturbations in some non-equilibrium gases

100%
Perelomova A.
Open Physics
|
2013
|
vol. 11
|
issue 11
1541-1547
EN
Evolution of sound in a relaxing gas whose properties vary in the course of wave propagation, is studied. A relaxing medium may reveal normal acoustic properties or be acoustically active. In the first case, losses in acoustic energy lead to an increase in internal energy of a gas similarly as it happens in Newtonian fluids. In the second case, acoustic energy increases in the course of sound propagation, and the internal energy of a medium decreases. Variations in the internal energy of a gas are proportional to some generic parameter, the sign of which is responsible for acoustical activity, and depends on intensity and shape of the sound waveform. Hysteresis curves in the plane of thermodynamic states are plotted. Curves for harmonic and several aperiodic sound impulses are plotted, discussed and compared.
3
Content available remote

Thermal self-action effects for acoustic beams containing fronts in a Maxwell relaxing fluid

100%
Perelomova A.
Open Physics
|
2014
|
vol. 12
|
issue 5
315-322
EN
This paper examines the thermal self-action of acoustic beams in a Maxwell relaxing fluid. This type of thermal self-action differs from that in a Newtonian fluid and behaves differently depending on a ratio of sound period and time of thermodynamic relaxation. The self-action which relates to sound beams containing shock fronts is also discussed. In addition, stationary and non-stationary types of self-action are considered.
4
Content available remote

Acoustic field and the entropy mode induced by it in a waveguide filled with some non-equilibrium gases

100%
Perelomova A.
Open Physics
|
2013
|
vol. 11
|
issue 3
380-386
EN
The non-linear propagation of an acoustic beam in a rectangular waveguide is considered. The medium of sound propagation, is a gas where thermodynamically non-equilibrium processes take place: such as exothermic chemical reactions or excitation of vibrational degrees of a molecule’s freedom. The incident and reflected compounds of the acoustic field do not interact in the leading order in the case of periodic weakly nonlinear sound with zero mean value of velocity. The acoustic heating or cooling in a waveguide is discussed.
5
Content available remote

Generation of the vorticity mode by sound in a Bingham plastic

64%
Perelomova A., Wojda P.
Open Physics
|
2011
|
vol. 9
|
issue 5
1135-1143
EN
This study investigates interaction between acoustic and non-acoustic modes, such as vorticity mode, in some class of a non-newtonian fluid called Bingham plastic. The instantaneous equations describing interaction between different modes are derived. The attention is paid to the nonlinear effects in the field of intense sound. The resulting equations which describe dynamics of both sound and the vorticity mode apply to both periodic and aperiodic sound of any waveform. They use only instantaneous quantities and do not imply averaging over the sound period. The theory is illustrated by an example of acoustic force of vorticity induced in the field of a Gaussian sound beam. Some unusual peculiarities in both sound and the vorticity induced in its field as compared to a newtonian fluid, are discovered.
6
Content available remote

Generation of the vorticity mode by sound in a vibrationally relaxing gas

64%
Perelomova A., Wojda P.
Open Physics
|
2012
|
vol. 10
|
issue 5
1116-1124
EN
The procedure of derivation of a new dynamical equation governing the vorticity mode that is generated by sound, is discussed in detail. It includes instantaneous quantities and does not require averaging over sound period. The resulting equation applies to both periodic and aperiodic sound as the origin of the vorticity mode. Under certain conditions, the direction of streamlines of the vorticity mode may be inverted as compared with that in a fluid with standard attenuation. This reflects an anomalous absorption of sound, when transfer of momentum of the vorticity mode into momentum of sound occurs. The theory is illustrated by a representative example of the generation of vorticity in a vibrationally relaxing gas in the field of periodic weakly diffracting acoustic beam.
7
Content available remote

The vortex flow caused by sound in a bubbly liquid

64%
Perelomova A., Wojda P.
Open Physics
|
2014
|
vol. 12
|
issue 5
305-314
EN
Generation of vorticity in the field of intense sound in a bubbly liquid in the free half-space is considered. The reasons for generation of vorticity are nonlinearity, diffraction, and dispersion. Acoustic streaming differs from that in a Newtonian fluid. Under some conditions, the vortex flow changes its direction. Conclusions concern streaming induced by a harmonic or an impulse Gaussian beam.
8
Content available remote

Nonlinear increase in bubbles radii caused by sound in a bubbly liquid

64%
Perelomova A., Pelc-Garska W.
Open Physics
|
2012
|
vol. 10
|
issue 1
151-158
EN
The nonlinear interaction of acoustic and entropy modes in a bubbly liquid is considered. The reasons for interaction are both nonlinearity and dispersion. In the field of intense sound, a decrease in the mixture density is predicted. That corresponds to the well-established growth of bubbles volumes due to rectified diffusion. The nonlinear interaction of modes as a reason for a bubble to grow due to sound, is discovered. The example considers variation in the mixture density and bubbles radii caused by acoustic soliton.
9
Content available remote

Efficiency of acoustic heating produced in the thermoviscous flow of a fluid with relaxation

64%
Perelomova A., Pelc-Garska W.
Open Physics
|
2010
|
vol. 8
|
issue 6
855-863
EN
Instantaneous acoustic heating of a fluid with thermodynamic relaxation is the subject of investigation. Among others, viscoelastic biological media described by the Maxwell model of the viscous stress tensor, belong to this type of fluid. The governing equation of acoustic heating is derived by means of the special linear combination of conservation equations in differential form, allowing the reduction of all acoustic terms in the linear part of the final equation, but preserving terms belonging to the thermal mode responsible for heating. The procedure of decomposition is valid for weakly nonlinear flows, resulting in the nonlinear terms responsible for the modes interaction. Nonlinear acoustic terms form a source of acoustic heating in the case of dominative sound, which reflects the thermoviscous and dispersive properties of a fluid. The method of deriving the governing equations does not need averaging over the sound period, and the final governing dynamic equation of the thermal mode is instantaneous. Some examples of acoustic heating are illustrated and discussed, conclusions about efficiency of heating caused by different sound impulses are made.
10
Content available remote

Generation of vorticity motion by sound in a chemically reacting gas and inversion of acoustic streaming in the non-equilibrium regime

64%
Perelomova A., Wojda P.
Open Physics
|
2011
|
vol. 9
|
issue 3
740-750
EN
Nonlinear stimulation of the vorticity mode caused by losses in the momentum of sound in a chemically reacting gas is considered. The instantaneous dynamic equation for the vorticity mode is derived. It includes a quadratic nonlinear acoustic source, which reflects the fact that the reason for the interaction between sound and the vorticity mode is nonlinear. Both periodic and aperiodic sound may be considered as the origin of the vorticity flow. The equation governing the mean flow (the acoustic streaming) in the field of periodic sound is also derived. In the non-equilibrium regime of a chemical reaction, there may exist streaming vortices whose direction of rotation is opposite to that of the vortices in the standard thermoviscous flows. For periodic sound, this is illustrated by an example. The theory and the example describe both equilibrium and non-equilibrium chemical reactions.
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