Quantum ion-acoustic solitary waves in weak relativistic plasma
Indian Academy of Sciences (India)
Biswajit Sahu
2011-06-01
Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized twospecies relativistic quantum plasma system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed Korteweg–de Vries (dKdV) equation by reductive perturbation method. A linear dispersion relation is also obtained taking into account the relativistic effect. The properties of quantum ion-acoustic solitary waves, obtained from the deformed KdV equation, are studied taking into account the quantum mechanical effects in the weak relativistic limit. It is found that relativistic effects signiﬁcantly modify the properties of quantum ion-acoustic waves. Also the effect of the quantum parameter on the nature of solitary wave solutions is studied in some detail.
Electron acoustic solitary waves with kappa-distributed electrons
Energy Technology Data Exchange (ETDEWEB)
Devanandhan, S; Singh, S V; Lakhina, G S, E-mail: satyavir@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai (India)
2011-08-01
Electron acoustic solitary waves are studied in a three-component, unmagnetized plasma composed of hot electrons, fluid cold electrons and ions having finite temperatures. Hot electrons are assumed to have kappa distribution. The Sagdeev pseudo-potential technique is used to study the arbitrary amplitude electron-acoustic solitary waves. It is found that inclusion of cold electron temperature shrinks the existence regime of the solitons, and soliton electric field amplitude decreases with an increase in cold electron temperature. A decrease in spectral index, {kappa}, i.e. an increase in the superthermal component of hot electrons, leads to a decrease in soliton electric field amplitude as well as the soliton velocity range. The soliton solutions do not exist beyond T{sub c}/T{sub h}>0.13 for {kappa}=3.0 and Mach number M=0.9 for the dayside auroral region parameters.
Effect of nonthermal ion distribution and dust temperature on nonlinear dust-acoustic solitary waves
Indian Academy of Sciences (India)
K Annou; R Annou
2012-01-01
Dust-acoustic solitary waves in unmagnetized dusty plasma whose constituents are inertial charged dust grains, Boltzmannian electrons and nonthermal ions have been investigated by taking into account ﬁnite dust temperature. The pseudopotential has been used to study solitary solution. The existence of solitary waves having negative potential is reported.
Experiments on the acoustic solitary wave generated thermoacoustically in a looped tube
Shimizu, Dai; Sugimoto, Nobumasa
2015-10-01
Emergence of an acoustic solitary wave is demonstrated in a gas-filled, looped tube with an array of Helmholtz resonators connected. The solitary wave is generated thermoacoustically and spontaneously by a pair of stacks positioned diametrically on exactly the opposite side of the loop. The temperature gradient is imposed on both stacks in the same sense along the tube. The stacks made of ceramics and of many square pores are sandwiched by hot and cold heat exchangers. The pressure profile measured and the propagation speed show good agreements with the theoretical ones of the acoustic solitary wave obtained by Sugimoto (J. Acoust. Soc. Am., 99, 1971-1976 (1996)).
Institute of Scientific and Technical Information of China (English)
Duan Wen-Shan
2004-01-01
The effect of dust charging and the influence of its adiabatic variation on dust acoustic waves is investigated. By employing the reductive perturbation technique we derived a Zakharov-Kuznetsov (ZK) equation for small amplitude dust acoustic waves. We have analytically verified that there are only rarefactive solitary waves for this system. The instability region for one-dimensional solitary wave under transverse perturbations has also been obtained. The obliquely propagating solitary waves to the z-direction for the ZK equation are given in this paper as well.
Institute of Scientific and Technical Information of China (English)
DUANWen－Shan
2002-01-01
By employing the reductive perturbation technique we derived a Kadomtsev-Petviashvili equation for unmagnetized dusty plasmas,It suggests that the nonlinear dust acoustic solitary waves with adiabatic variation of dust charge are stable even there are some higher order transverse perturbatoins,There are only rarefactive solitary waves for this system which has been verified analytically in this paper.
Experimental study of nonlinear dust acoustic solitary waves in a dusty plasma
Bandyopadhyay, P; Sen, A; Kaw, P K
2008-01-01
The excitation and propagation of finite amplitude low frequency solitary waves are investigated in an Argon plasma impregnated with kaolin dust particles. A nonlinear longitudinal dust acoustic solitary wave is excited by pulse modulating the discharge voltage with a negative potential. It is found that the velocity of the solitary wave increases and the width decreases with the increase of the modulating voltage, but the product of the solitary wave amplitude and the square of the width remains nearly constant. The experimental findings are compared with analytic soliton solutions of a model Kortweg-de Vries equation.
Dust-acoustic solitary waves in a dusty plasma with two-temperature nonthermal ions
Indian Academy of Sciences (India)
Zhi-Jian Zhou; Hong-Yan Wang; Kai-Biao Zhang
2012-01-01
By using reductive perturbation method, the nonlinear propagation of dust-acoustic waves in a dusty plasma (containing a negatively charged dust ﬂuid, Boltzmann distributed electrons and two-temperature nonthermal ions) is investigated. The effects of two-temperature nonthermal ions on the basic properties of small but ﬁnite amplitude nonlinear dust-acoustic waves are examined. It is found that two-temperature nonthermal ions affect the basic properties of the dust-acoustic solitary waves. It is also observed that only compressive solitary waves exist in this system.
Institute of Scientific and Technical Information of China (English)
DUAN Wen-Shan
2002-01-01
By employing the reductive perturbation technique we derived a Kadomtsev-Petviashvili equation forunmagnetized dusty plasmas. It suggests that the nonlinear dust acoustic solitary waves with adiabatic variation of dustcharge are stable even there are some higher order transverse perturbatoins. There are only rarefactive solitary wavesfor this system which has been verified analytically in this paper.
Directory of Open Access Journals (Sweden)
S. S. Ghosh
2004-01-01
Full Text Available The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region.
Modeling of modified electron-acoustic solitary waves in a relativistic degenerate plasma
Energy Technology Data Exchange (ETDEWEB)
Hossen, M. R.; Mamun, A. A. [Jahangirnagar University, Savar, Dhaka (Bangladesh)
2014-12-15
The modeling of a theoretical and numerical study on the nonlinear propagation of modified electron-acoustic (mEA) solitary waves has been carried out in an unmagnetized, collisionless, relativistic, degenerate quantum plasma (containing non-relativistic degenerate inertial cold electrons, both non-relativistic and ultra-relativistic degenerate hot electron and inertial positron fluids, and positively-charged static ions). A reductive perturbation technique is used to derive the planar and the nonplanar Korteweg-de Vries (K-dV) equations, which admit a localized wave solution for the solitary profile. The solitary wave's characteristics are found to have been influenced significantly for the non-relativistic and the ultra-relativistic limits. The mEA solitary waves are also found to have been significantly modified due to the effects of the degenerate pressure and the number densities of this dense plasma's constituents. The properties of the planar K-dV solitary wave are quite different from those of the nonplanar K-dV solitary wave. The relevance of our results to astrophysical objects (like white dwarfs and neutron stars), which are of scientific interest, is briefly mentioned.
Energy Technology Data Exchange (ETDEWEB)
El-Labany, S. K.; Behery, E. E. [Department of Physics, Faculty of Science, Damietta University, P.O. Box 34517 New Damietta (Egypt); El-Shamy, E. F. [Department of Physics, Faculty of Science, Damietta University, P.O. Box 34517 New Damietta (Egypt); Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004 Abha (Saudi Arabia)
2013-12-15
The propagation and oblique collision of ion-acoustic (IA) solitary waves in a magnetized dusty electronegative plasma consisting of cold mobile positive ions, Boltzmann negative ions, Boltzmann electrons, and stationary positive/negative dust particles are studied. The extended Poincaré-Lighthill-Kuo perturbation method is employed to derive the Korteweg-de Vries equations and the corresponding expressions for the phase shifts after collision between two IA solitary waves. It turns out that the angle of collision, the temperature and density of negative ions, and the dust density of opposite polarity have reasonable effects on the phase shift. Clearly, the numerical results demonstrated that the IA solitary waves are delayed after the oblique collision. The current finding of this work is applicable in many plasma environments having negative ion species, such as D- and F-regions of the Earth's ionosphere and some laboratory plasma experiments.
Institute of Scientific and Technical Information of China (English)
XueJu-Kui; LangHe
2003-01-01
The effect of dust charge variation on the dust-acoustic solitary structures is investigated in a warm magnetized two-ion-temperature dusty plasma consisting of a negatively and variably charged extremely massive dust fluid and ions of two different temperatures. It is shown that the dust charge variation as well as the presence of a second component of ions would modify the properties of the dust-acoustic solitary structures and may exite both dust-acoustic solitary holes (soliton waves with a density dip) and positive solitons (soliton waves with a density hump).
Institute of Scientific and Technical Information of China (English)
薛具奎; 郎和
2003-01-01
The effect of dust charge variation on the dust-acoustic solitary structures is investigated in a warm magnetized two-ion-temperature dusty plasma consisting of a negatively and variably charged extremely massive dust fluid and ions of two different temperatures. It is shown that the dust charge variation as well as the presence of a second component of ions would modify the properties of the dust-acoustic solitary structures and may excite both dust-acoustic solitary holes (soliton waves with a density dip) and positive solitons (soliton waves with a density hump).
Effect of polarization force on the propagation of dust acoustic solitary waves
International Nuclear Information System (INIS)
We report the modifications in the propagation characteristics of dust acoustic solitary waves (DASWs) due to the polarization force acting on micron-size dust particles in a non-uniform plasma. In the small amplitude limit, we derive a K-dV-type equation and show that there is an increase in the amplitude and a reduction in the width of a solitary structure as the polarization force is enhanced for a given Mach number. For arbitrary amplitude waves we employ the Sagdeev potential method and find that the range of Mach numbers where solitary structures can exist becomes narrower in the presence of the polarization interaction. In both limits there exists a critical value of grain size beyond which the DASW cannot propagate.
Effect of polarization force on the propagation of dust acoustic solitary waves
Energy Technology Data Exchange (ETDEWEB)
Bandyopadhyay, P; Konopka, U; Khrapak, S A; Morfill, G E [Max-Planck Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany); Sen, A, E-mail: pintu@mpe.mpg.d [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India)
2010-07-15
We report the modifications in the propagation characteristics of dust acoustic solitary waves (DASWs) due to the polarization force acting on micron-size dust particles in a non-uniform plasma. In the small amplitude limit, we derive a K-dV-type equation and show that there is an increase in the amplitude and a reduction in the width of a solitary structure as the polarization force is enhanced for a given Mach number. For arbitrary amplitude waves we employ the Sagdeev potential method and find that the range of Mach numbers where solitary structures can exist becomes narrower in the presence of the polarization interaction. In both limits there exists a critical value of grain size beyond which the DASW cannot propagate.
Oblique propagation of ion-acoustic solitary waves in a magnetized electron-positron-ion plasma
Energy Technology Data Exchange (ETDEWEB)
Ferdousi, M.; Sultana, S.; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh)
2015-03-15
The properties of obliquely propagating ion-acoustic solitary waves in the presence of ambient magnetic field have been investigated theoretically in an electron-positron-ion nonthermal plasma. The plasma nonthermality is introduced via the q-nonextensive distribution of electrons and positrons. The Korteweg-de Vries (K-dV) and modified K-dV (mK-dV) equations are derived by adopting reductive perturbation method. The solution of K-dV and modified K-dV equation, which describes the solitary wave characteristics in the long wavelength limit, is obtained by steady state approach. It is seen that the electron and positron nonextensivity and external magnetic field (obliqueness) have significant effects on the characteristics of solitary waves. A critical value of nonextensivity is found for which solitary structures transit from positive to negative potential. The findings of this investigation may be used in understanding the wave propagation in laboratory and space plasmas where static external magnetic field is present.
Propagation and interaction of ion-acoustic solitary waves in a quantum electron-positron-ion plasma
Institute of Scientific and Technical Information of China (English)
Han Jiu-Ning; Luo Jun-Hua; Sun Gui-Hua; Liu Zhen-Lai; Li Shou-Yi
2011-01-01
This paper discusses the existence of ion-acoustic solitary waves and their interaction in a dense quantum electron-positron-ion plasma by using the quantum hydrodynamic equations. The extended Poincaré-Lighthill-Kuo perturbation method is used to derive the Korteweg-de Vries equations for quantum ion-acoustic solitary waves in this plasma. The effects of the ratio of positrons to ions unperturbation number density p and the quantum diffraction parameter He (Hp) on the newly formed wave during interaction, and the phase shift of the colliding solitary waves are studied. It is found that the interaction between two solitary waves fits linear superposition principle and these plasma parameters have significantly influence on the newly formed wave and phase shift of the colliding solitary waves. The investigations should be useful for understanding the propagation and interaction of ion-acoustic solitary waves in dense astrophysical plasmas (such as white dwarfs) as well as in intense laser-solid matter interaction experiments.
Heavy-ion-acoustic solitary and shock waves in an adiabatic multi-ion plasma
Energy Technology Data Exchange (ETDEWEB)
Hossen, M.A.; Rahman, M.M.; Mamun, A.A., E-mail: armanplasma@gmail.com [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Hossen, M.R. [Department of Natural Sciences, Daffodil International University, Dhanmondi, Dhaka (Bangladesh)
2015-08-15
The standard reductive perturbation method has been employed to derive the Korteweg-deVries (K-dV) and Burgers (BG) equations to investigate the basic properties of heavy-ion-acoustic (HIA) waves in a plasma system which is supposed to be composed of nonthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions. The HIA solitary and shock structures are found to exist with either positive or negative potential. It is found that the effects of adiabaticity of inertial heavy ions, nonthermality of electrons, and number densities of plasma components significantly modify the basic properties of the HIA solitary and shock waves. The implications of our results may be helpful in understanding the electrostatic perturbations in various laboratory and astrophysical plasma environments. (author)
Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements
Directory of Open Access Journals (Sweden)
J. Ekeberg
2010-06-01
Full Text Available Spectra measured by incoherent scatter radars are formed predominantly by scattering of the incident signal off ion-acoustic and Langmuir waves in the ionosphere. Occasionally, the upshifted and/or downshifted lines produced by the ion-acoustic waves are enhanced well above thermal levels and referred to as naturally enhanced ion-acoustic lines. In this paper, we study another kind of enhancement, which is spectrally uniform over the whole ion-line, i.e. the up- and downshifted shoulder and the spectral valley in between. Based on observations made with the EISCAT Svalbard radar (ESR facility, we investigate the transient and spectrally uniform power enhancements, which can be explained by ion-acoustic solitary waves. We use a theory of nonlinear waves in a magnetized plasma to determine the properties of such waves and evaluate their effects on scattered signals measured by ESR. We suggest a new mechanism that can explain backscattered power enhancements by one order of magnitude above the thermal level and show that it is consistent with observations.
Hafez, M. G.; Roy, N. C.; Talukder, M. R.; Hossain Ali, M.
2016-08-01
The characteristics of the nonlinear oblique propagation of ion acoustic solitary waves in unmagnetized plasmas consisting of Boltzmann positrons, trapped electrons and ions are investigated. The modified Kadomtsev-Petviashivili ( m K P ) equation is derived employing the reductive perturbation technique. The parametric effects on phase velocity, Sagdeev potential, amplitude and width of solitons, and electrostatic ion acoustic solitary structures are graphically presented with the relevant physical explanations. This study may be useful for the better understanding of physical phenomena concerned in plasmas in which the effects of trapped electrons control the dynamics of wave.
Sultana, S; Hellberg, M A
2012-01-01
The linear and nonlinear properties of large amplitude electron-acoustic waves are investigated in a magnetized plasma comprising two distinct electron populations (hot and cold) and immobile ions. The hot electrons are assumed to be in a non-Maxwellian state, characterized by an excess of superthermal particles, here modelled by a kappa-type long-tailed distribution function. Waves are assumed to propagate obliquely to the ambient magnetic field. Two types of electrostatic modes are shown to exist in the linear regime, and their properties are briefly analyzed. A nonlinear pseudopotential type analysis reveals the existence of large amplitude electrostatic solitary waves and allows for an investigation of their propagation characteristics and existence domain, in terms of the soliton speed (Mach number). The effects of the key plasma configuration parameters, namely, the superthermality index and the cold electron density, on the soliton characteristics and existence domain, are studied. The role of obliquen...
Indian Academy of Sciences (India)
Tarsem Singh Gill; Harvinder Kaur
2000-11-01
The effects of nonthermal ion distribution and ﬁnite dust temperature are incorporated in the investigation of nonlinear dust acoustic waves in an unmagnetized dusty plasma. Sagdeev pseudopotential method which takes into account the full nonlinearity of plasma equations, is used here to study solitary wave solutions. Possibility of co-existence of refractive and compressive solitons as a function of Mach number, dust temperature and concentration of nonthermal ions, is considered. For the ﬁxed value of nonthermal ions, it is found that the effect of increase in dust temperature is to reduce the range of co-existence of compressive and refractive solitons. Particular concentration of nonthermal ions results in disappearance of refractive solitons while the decrease in dust temperature, at this concentration restores the lost refractive solitons.
Dust acoustic solitary and shock waves in strongly coupled dusty plasmas with nonthermal ions
Indian Academy of Sciences (India)
Hamid Reza Pakzad; Kurosh Javidan
2009-11-01
The Korteweg–de Vries–Burgers (KdV–Burgers) equation and modified Korteweg–de Vries–Burgers equation are derived in strongly coupled dusty plasmas containing nonthermal ions and Boltzmann distributed electrons. It is found that solitary waves and shock waves can be produced in this medium. The effects of important parameters such as ion nonthermal parameter, temperature, density and velocity on the properties of shock waves and solitary waves are discussed.
Institute of Scientific and Technical Information of China (English)
LIU Shi-Da; FU Zun-Tao; LIU Shi-Kuo; XIN Guo-Jun; LIANG Fu-Ming
2004-01-01
In this paper, it is shown that the homoclinic orbits exist in iterated functional systems, so do the solitary wave structures. Moreover, Harr father wavelet, Mexican Cap wavelet, and other closed form wavelets have this solitary wave structure, too. So wavelet is a certain kind of solitary wave.
Institute of Scientific and Technical Information of China (English)
HAN Jiu-Ning; DUAN Wen-Shan; TIAN Duo-Xiang; LIANG Gui-Zhen; LI Xiao-Li; YANG Xiao-Xia
2008-01-01
We study the propagation and interaction of ion-acoustic solitary waves in a simple two-dimensional plasma by using the extended Poincaré-Lighthill-Kuo perturbation method. We consider the interaction between two ion-acoustic solitary waves with different propagation directions in such a system, and obtain two Korteweg-de Vries equations for small but finite amplitude solitary waves along both ξ and η trajectories. The effects of the ratio of ion temperature a, the ratio of heat capacity γ and the colliding angle α on the amplitude, the width of the new nonlinear wave created by the collision between two solitary waves are studied. The effects of these parameters on both the colliding solitary waves are examined as well. It is found that all the above-mentioned parameters have significant effects on the properties of these nonlinear waves.
Indian Academy of Sciences (India)
O Rahman; A A Mamun
2013-06-01
A theoretical investigation of dust-acoustic solitary waves in three-component unmagnetized dusty plasma consisting of trapped electrons, Maxwellian ions, and arbitrarily charged cold mobile dust was done. It has been found that, owing to the departure from the Maxwellian electron distribution to a vortex-like one, the dynamics of small but finite amplitude dust-acoustic (DA) waves is governed by a nonlinear equation of modified Korteweg–de Vries (mKdV) type (instead of KdV). The reductive perturbation method was employed to study the basic features (amplitude, width, speed, etc.) of DA solitary waves which are significantly modified by the presence of trapped electrons. The implications of our results in space and laboratory plasmas are briefly discussed.
Energy Technology Data Exchange (ETDEWEB)
Abdelwahed, H. G. [Department of Physics, College of Sciences and Humanitarian Studies, Salman Bin Abdulaziz University, Al-Kharj (Saudi Arabia); Theoretical Physics Group, Faculty of Science, Mansoura University, Mansoura (Egypt); El-Shewy, E. K. [Theoretical Physics Group, Faculty of Science, Mansoura University, Mansoura (Egypt)
2012-07-15
Nonlinear ion-acoustic solitary waves in a warm collisionless plasma with nonthermal electrons are investigated by a direct analysis of the field equations. The Sagdeev's potential is obtained in terms of ion acoustic speed by simply solving an algebraic equation. It is found that the amplitude and width of the ion-acoustic solitons as well as the parametric regime where the solitons can exist are sensitive to the population of energetic non-thermal electrons. The soliton and double layer solutions are obtained as a small amplitude approximation.
Landau damping effects on dust-acoustic solitary waves in a dusty negative-ion plasma
Barman, A
2014-01-01
The nonlinear theory of dust-acoustic waves (DAWs) with Landau damping is studied in an unmagnetized dusty negative-ion plasma in the extreme conditions when the free electrons are absent. The cold massive charged dusts are described by fluid equations, whereas the two-species of ions (positive and negative) are described by the kinetic Vlasov equations. A Korteweg de-Vries (KdV) equation with Landau damping, governing the dynamics of weakly nonlinear and weakly dispersive DAWs, is derived following Ott and Sudan [Phys. Fluids {\\bf 12}, 2388 (1969)]. It is shown that for some typical laboratory and space plasmas, the Landau damping (and the nonlinear) effects are more pronounced than the finite Debye length (dispersive) effects for which the KdV soliton theory is not applicable to DAWs in dusty pair-ion plasmas. The properties of the linear phase velocity, solitary wave amplitudes (in presence and absence of the Landau damping) as well as the Landau damping rate are studied with the effects of the positive io...
El-Wakil, S A; El-Shewy, E K; Abd-El-Hamid, H M
2010-01-01
A theoretical investigation has been made of electron acoustic wave propagating in unmagnetized collisionless plasma consisting of a cold electron fluid and isothermal ions with two different temperatures obeying Boltzmann type distributions. Based on the pseudo-potential approach, large amplitude potential structures and the existence of Solitary waves are discussed. The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV) equation for small but finite amplitude electrostatic waves. An algebraic method with computerized symbolic computation, which greatly exceeds the applicability of the existing tanh, extended tanh methods in obtaining a series of exact solutions of the KdV equation, is used here. Numerical studies have been made using plasma parameters close to those values corresponding to Earth's plasma sheet boundary layer region reveals different solutions i.e., bell-shaped solitary pulses and singularity solutions at a finite point which called "blowup" solutions, Jaco...
Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows
International Nuclear Information System (INIS)
The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Korteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration
Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows
Energy Technology Data Exchange (ETDEWEB)
Saleem, H. [Department of Space Science, Institute of Space Technology, 1-Islamabad Highway, Islamabad (Pakistan); Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); Ali, S. [Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); National Centre for Physics (NCP) at Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Haque, Q. [Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); National Centre for Physics (NCP) at Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Theoretical Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)
2015-08-15
The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Korteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.
Jaiswal, S; Sen, A
2016-01-01
We investigate the propagation characteristics of two counter propagating dust acoustic solitary waves (DASWs) undergoing a head-on collision, in the presence of strong coupling between micron sized charged dust particles in a complex plasma. A coupled set of nonlinear dynamical equations describing the evolution of the two DASWs using the extended Poincar?e{Lighthill{Kuo perturbation technique is derived. The nature and extent of post collision phase-shifts of these solitary waves are studied over a wide range of dusty plasma parameters in a strongly and a weakly coupled medium. We ?nd a signi?cant change in the nature and amount of phase delay in the strongly coupled regime as compared to a weakly coupled regime. The phase shift is seen to change its sign beyond a threshold value of compressibility of the medium for a given set of dusty plasma parameters.
Energy Technology Data Exchange (ETDEWEB)
EL-Shamy, E. F., E-mail: emadel-shamy@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta 34517, Egypt and Department of Physics, College of Science, King Khalid University, Abha P.O. 9004 (Saudi Arabia)
2014-08-15
The solitary structures of multi–dimensional ion-acoustic solitary waves (IASWs) have been considered in magnetoplasmas consisting of electron-positron-ion with high-energy (superthermal) electrons and positrons are investigated. Using a reductive perturbation method, a nonlinear Zakharov-Kuznetsov equation is derived. The multi-dimensional instability of obliquely propagating (with respect to the external magnetic field) IASWs has been studied by the small-k (long wavelength plane wave) expansion perturbation method. The instability condition and the growth rate of the instability have been derived. It is shown that the instability criterion and their growth rate depend on the parameter measuring the superthermality, the ion gyrofrequency, the unperturbed positrons-to-ions density ratio, the direction cosine, and the ion-to-electron temperature ratio. Clearly, the study of our model under consideration is helpful for explaining the propagation and the instability of IASWs in space observations of magnetoplasmas with superthermal electrons and positrons.
Sardar, Sankirtan; Bandyopadhyay, Anup; Das, K. P.
2016-07-01
A three-dimensional KP (Kadomtsev Petviashvili) equation is derived here describing the propagation of weakly nonlinear and weakly dispersive dust ion acoustic wave in a collisionless unmagnetized plasma consisting of warm adiabatic ions, static negatively charged dust grains, nonthermal electrons, and isothermal positrons. When the coefficient of the nonlinear term of the KP-equation vanishes an appropriate modified KP (MKP) equation describing the propagation of dust ion acoustic wave is derived. Again when the coefficient of the nonlinear term of this MKP equation vanishes, a further modified KP equation is derived. Finally, the stability of the solitary wave solutions of the KP and the different modified KP equations are investigated by the small-k perturbation expansion method of Rowlands and Infeld [J. Plasma Phys. 3, 567 (1969); 8, 105 (1972); 10, 293 (1973); 33, 171 (1985); 41, 139 (1989); Sov. Phys. - JETP 38, 494 (1974)] at the lowest order of k, where k is the wave number of a long-wavelength plane-wave perturbation. The solitary wave solutions of the different evolution equations are found to be stable at this order.
Energy Technology Data Exchange (ETDEWEB)
Singh, S. V.; Devanandhan, S.; Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Bharuthram, R. [University of the Western Cape, Bellville (South Africa)
2013-01-15
Obliquely propagating ion-acoustic soliatry waves are examined in a magnetized plasma composed of kappa distributed electrons and fluid ions with finite temperature. The Sagdeev potential approach is used to study the properties of finite amplitude solitary waves. Using a quasi-neutrality condition, it is possible to reduce the set of equations to a single equation (energy integral equation), which describes the evolution of ion-acoustic solitary waves in magnetized plasmas. The temperature of warm ions affects the speed, amplitude, width, and pulse duration of solitons. Both the critical and the upper Mach numbers are increased by an increase in the ion temperature. The ion-acoustic soliton amplitude increases with the increase in superthermality of electrons. For auroral plasma parameters, the model predicts the soliton speed, amplitude, width, and pulse duration, respectively, to be in the range of (28.7-31.8) km/s, (0.18-20.1) mV/m; (590-167) m, and (20.5-5.25) ms, which are in good agreement with Viking observations.
Institute of Scientific and Technical Information of China (English)
LIN Mai-Mai; DUAN Wen-Shan
2007-01-01
In this paper,(2+1)-dimensional electron acoustic waves (EAW) in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique,respectively.The dispersion relation and a modified Kadomtsev-Petviashvili (KP) equation have been obtained for the EAW in the plasma considering a cold electron fluid and a vortex-like hot electrons.It is found from some numerical results that the parameter β (the ratio of the free hot electron temperature to the hot trapped electron temperature) effects on the amplitude and the width of the electron acoustic solitary waves (EASW).It can be indicated that the free hot electron temperature and the hot trapped electron temperature have very important effect on the characters of the propagation for the EASW.
Energy Technology Data Exchange (ETDEWEB)
Uddin, M. J., E-mail: josim.phys2007@gmail.com; Alam, M. S.; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh)
2015-02-15
Nonplanar (cylindrical and spherical) positron-acoustic (PA) Gardner solitary waves (SWs) in an unmagnetized plasma system consisting of immobile positive ions, mobile cold positrons, and superthermal (kappa distributed) hot positrons and electrons are investigated. The modified Gardner equation is derived by using the reductive perturbation technique. The effects of cylindrical and spherical geometries, superthermal parameter of hot positrons and electrons, relative temperature ratios, and relative number density ratios on the PA Gardner SWs are studied by using the numerical simulations. The implications of our results in various space and laboratory plasma environments are briefly discussed.
Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements
J. Ekeberg; Wannberg, G.; Eliasson, L; Stasiewicz, K.
2010-01-01
Spectra measured by incoherent scatter radars are formed predominantly by scattering of the incident signal off ion-acoustic and Langmuir waves in the ionosphere. Occasionally, the upshifted and/or downshifted lines produced by the ion-acoustic waves are enhanced well above thermal levels and referred to as naturally enhanced ion-acoustic lines. In this paper, we study another kind of enhancement, which is spectrally uniform over the whole ion-line, i.e. the up- and downshifted shoulder and t...
International Nuclear Information System (INIS)
A theoretical investigation is carried out to study the existence and characteristics of propagation of dust-acoustic (DA) waves in an electron-depleted dusty plasma with two-temperature ions, which are modeled by kappa distribution functions. A three-dimensional cylindrical Kadomtsev-Petviashvili equation governing evolution of small but finite amplitude DA waves is derived by means of a reductive perturbation method. The influence of physical parameters on solitary wave structure is examined. Furthermore, the energy integral equation is used to study the existence domains of the localized structures. It is found that the present model can be employed to describe the existence of positive as well as negative polarity DA solitary waves by selecting special values for parameters of the system, e.g., superthermal index of cold and/or hot ions, cold to hot ion density ratio, and hot to cold ion temperature ratio. This model may be useful to understand the excitation of nonlinear DA waves in astrophysical objects.
Study of trapping effect on ion-acoustic solitary waves based on a fully kinetic simulation approach
Jenab, S M
2016-01-01
A fully kinetic simulation approach, treating each plasma component based on the Vlasov equation, is adopted to study the disintegration of an initial density perturbation (IDP) into a number of ion-acoustic solitary waves (IASWs) in the presence of the trapping effect of electrons. The non-linear fluid theory developed by Schamel has identified three separate regimes of ion-acoustic solitary waves based on the trapping parameter. Here, the disintegration process and the resulting self-consistent IASWs are studied in a wide range of trapping parameters covering all the three regimes continuously. The dependency of features such as the time of disintegration, the number, speed and size of IASWs on the trapping parameter are focused upon. It is shown that an increase in this parameter slows down the propagation of IASWs while decreases their sizes in the phase space. These features of IASWs tend to saturate for large value of trapping parameters. The disintegration time shows a more complicated behavior than wh...
Tribeche, Mouloud; Mayout, Saliha
2016-07-01
The combined effects of ionization, ion loss and electron suprathermality on dust ion- acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg- de Vries (dK-- dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK- dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the DIA solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.
Guo, Shimin; Mei, Liquan; He, Ya-Ling; Ma, Chenchen; Sun, Youfa
2016-10-01
The nonlinear behavior of an ion-acoustic wave packet is investigated in a three-component plasma consisting of warm ions, nonthermal electrons and positrons. The nonthermal components are assumed to be inertialess and hot where they are modeled by the kappa distribution. The relevant processes, including the kinematic viscosity amongst the plasma constituents and the collision between ions and neutrals, are taken into consideration. It is shown that the dynamics of the modulated ion-acoustic wave is governed by the generalized complex Ginzburg-Landau equation with a linear dissipative term. The dispersion relation and modulation instability criterion for the generalized complex Ginzburg-Landau equation are investigated numerically. In the general dissipation regime, the effect of the plasma parameters on the dissipative solitary (dissipative soliton) and shock waves is also discussed in detail. The project is supported by NSF of China (11501441, 11371289, 11371288), National Natural Science Foundation of China (U1261112), China Postdoctoral Science Foundation (2014M560756), and Fundamental Research Funds for the Central Universities (xjj2015067).
Hot Dust Acoustic Solitary Waves in Dust Plasma with Variable Dust Charge
Institute of Scientific and Technical Information of China (English)
段文山; 吕克朴; 赵金保
2001-01-01
Considering the variation of dust charges, we have analytically studied the governing equation for the system with the same model as that for cold dust acoustic waves in a demagnetized plasma but with the contribution of hot dust. The result indicates that the governing equation is also a Kortweg-de Vries equation, although its amplitude and width will be smaller compared with the cold dust case.
Exciton solitary waves (exolitons)
International Nuclear Information System (INIS)
The soliton theory is briefly explained with regard to cooperative phenomena in one-dimensional systems. The study of the dynamics of a one-dimensional lattice shows that nonlinear phonon interaction results in the production of a solitary wave. The procedure is indicated for the mathematical solution of the problem of the exciton-phonon interaction. (M.S.)
Solitary waves on tensegrity lattices
Fraternali, F.; Senatore, L.; Daraio, C.
2012-06-01
We study the dynamics of lattices formed by masses connected through tensegrity prisms. By employing analytic and numerical arguments, we show that such structures support two limit dynamic regimes controlled by the prisms' properties: (i) in the low-energy (sonic) regime the system supports the formation and propagation of solitary waves which exhibit sech2 shape and (ii) in the high-energy (ultrasonic) regime the system supports atomic-scale localization. Such peculiar features found in periodic arrays of tensegrity structures suggest their use for the creation of new composite materials (here called "tensegrity materials") of potential interest for applications in impact absorption, energy localization and in new acoustic devices.
Solitary waves on nonlinear elastic rods. I
DEFF Research Database (Denmark)
Sørensen, Mads Peter; Christiansen, Peter Leth; Lomdahl, P. S.
1984-01-01
Acoustic waves on elastic rods with circular cross section are governed by improved Boussinesq equations when transverse motion and nonlinearity in the elastic medium are taken into account. Solitary wave solutions to these equations have been found. The present paper treats the interaction between...... the solitary waves numerically. It is demonstrated that the waves behave almost like solitons in agreement with the fact that the improved Boussinesq equations are nearly integrable. Thus three conservation theorems can be derived from the equations. A new subsonic quasibreather is found in the case of a cubic...
Institute of Scientific and Technical Information of China (English)
CHEN Jian-Hong; WEI Nan-Xia
2009-01-01
Taking into account the combined effects of the external magnetic field, adiabatic dust charge fluctuation and collisions occurring between the charged dust gains and neutral gas particles (dust-neutral collisions), the dust-acoustic solitary waves in three-dimensional uniform dusty plasmas are investigated analytically. By using the reductive perturbation method, the Korteweg-de Vries (KdV) equation governing the dust-acoustic solitary waves is obtained. The present analytical results show that only rarefactive solitary waves exist in this system. It is also found that the effects of the wave vector along the z-direction, dust charge variation, collisional frequency, the plasma density, and temperature ratio can significantly influence the characteristics of low-frequency wave modes. Moreover, for the collisional dusty plasmas, there is a certain critical value μc of the plasma density ratio #, if μ < μc, the width of the waves increases with μ, otherwise the width of waves decreases with μ.
Indian Academy of Sciences (India)
Uday Narayan Ghosh; Prasantha Chatterjee; Deb Kumar Ghosh
2013-10-01
Interaction of nonplanar ion-acoustic solitary waves is an important source of information for studying the nature and characteristics of ion-acoustic solitary waves (IASWs). The head-on collision between two cylindrical/spherical IASWs in un-magnetized plasmas comprising of nonthermal distributed electrons and warm ions is investigated using the extended version of Poincaré–Lighthill–Kuo (PLK) perturbation method. How the interactions are taking place in cylindrical and spherical geometries are shown numerically. Analytical phase shifts are derived for nonplanar geometry. The effects of the ion to electron temperature parameter and the nonthermal electrons parameter on the phase shift are studied. It is shown that the properties of the interaction of IASWs in different geometries are very different.
Global Attraction to Solitary Waves
Komech, Andrey
2009-01-01
The long time asymptotics for nonlinear wave equations have been the subject of intensive research, starting with the pioneering papers by Segal, Strauss, and Morawetz, where the nonlinear scattering and local attraction to zero were considered. Global attraction (for large initial data) to zero may not hold if there are quasistationary solitary wave solutions. We will call such solutions "solitary waves". Other appropriate names are "nonlinear eigenfunctions" and "quantum stationary states"....
Shahmohammadi, Nafise; Dorranian, Davoud
2015-10-01
Simultaneous effects of dust charge fluctuation and nonthermal ions on the threshold point and growth rate of three-dimensional instability of dust-acoustic solitary waves (DASW) in magnetized dusty plasma have been investigated. In this model, dusty plasma consists of Maxwellian electrons, nonthermal ions, and micron size negatively charged dust particles. Modified Zakharov-Kuznetsov equation for DASW was derived employing a reductive perturbation method and its solitary answer under the influence of dust charge fluctuation and nonthermal ions has been studied. The dispersion relation of DASW has been derived using a small-k perturbation method. Results show that the direction and the magnitude of external magnetic field at which the instability takes place are strongly affected by the rate of dust charge fluctuation and nonthermality of ions. With increasing the number of nonthermal ions, the growth rate of instability decreases, while increasing the dust charge fluctuation increases the growth rate of instability.
Energy Technology Data Exchange (ETDEWEB)
Shahmohammadi, Nafise; Dorranian, Davoud, E-mail: doran@srbiau.ac.ir [Laser Lab., Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)
2015-10-15
Simultaneous effects of dust charge fluctuation and nonthermal ions on the threshold point and growth rate of three-dimensional instability of dust-acoustic solitary waves (DASW) in magnetized dusty plasma have been investigated. In this model, dusty plasma consists of Maxwellian electrons, nonthermal ions, and micron size negatively charged dust particles. Modified Zakharov-Kuznetsov equation for DASW was derived employing a reductive perturbation method and its solitary answer under the influence of dust charge fluctuation and nonthermal ions has been studied. The dispersion relation of DASW has been derived using a small-k perturbation method. Results show that the direction and the magnitude of external magnetic field at which the instability takes place are strongly affected by the rate of dust charge fluctuation and nonthermality of ions. With increasing the number of nonthermal ions, the growth rate of instability decreases, while increasing the dust charge fluctuation increases the growth rate of instability.
Shallow Water Waves and Solitary Waves
Hereman, Willy
2013-01-01
Encyclopedic article covering shallow water wave models used in oceanography and atmospheric science. Sections: Definition of the Subject; Introduction and Historical Perspective; Completely Integrable Shallow Water Wave Equations; Shallow Water Wave Equations of Geophysical Fluid Dynamics; Computation of Solitary Wave Solutions; Numerical Methods; Water Wave Experiments and Observations; Future Directions, and Bibliography.
Oblique solitary waves in a five component plasma
Energy Technology Data Exchange (ETDEWEB)
Sijo, S.; Manesh, M.; Sreekala, G.; Venugopal, C., E-mail: cvgmgphys@yahoo.co.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, 686 560 Kerala (India); Neethu, T. W. [Department of Physics, CMS College, Mahatma Gandhi University, Kottayam, 686 001 Kerala (India); Renuka, G. [Kerala State Council for Science, Technology and Environment, Thiruvananthapuram, 695 004 Kerala (India)
2015-12-15
We investigate the influence of a second electron component on oblique dust ion acoustic solitary waves in a five component plasma consisting of positively and negatively charged dust, hydrogen ions, and hotter and colder electrons. Of these, the heavier dust and colder photo-electrons are of cometary origin while the other two are of solar origin; electron components are described by kappa distributions. The K-dV equation is derived, and different attributes of the soliton such as amplitude and width are plotted for parameters relevant to comet Halley. We find that the second electron component has a profound influence on the solitary wave, decreasing both its amplitude and width. The normalized hydrogen density strongly influences the solitary wave by decreasing its width; the amplitude of the solitary wave, however, increases with increasing solar electron temperatures.
Bulk solitary waves in elastic solids
Samsonov, A. M.; Dreiden, G. V.; Semenova, I. V.; Shvartz, A. G.
2015-10-01
A short and object oriented conspectus of bulk solitary wave theory, numerical simulations and real experiments in condensed matter is given. Upon a brief description of the soliton history and development we focus on bulk solitary waves of strain, also known as waves of density and, sometimes, as elastic and/or acoustic solitons. We consider the problem of nonlinear bulk wave generation and detection in basic structural elements, rods, plates and shells, that are exhaustively studied and widely used in physics and engineering. However, it is mostly valid for linear elasticity, whereas dynamic nonlinear theory of these elements is still far from being completed. In order to show how the nonlinear waves can be used in various applications, we studied the solitary elastic wave propagation along lengthy wave guides, and remarkably small attenuation of elastic solitons was proven in physical experiments. Both theory and generation for strain soliton in a shell, however, remained unsolved problems until recently, and we consider in more details the nonlinear bulk wave propagation in a shell. We studied an axially symmetric deformation of an infinite nonlinearly elastic cylindrical shell without torsion. The problem for bulk longitudinal waves is shown to be reducible to the one equation, if a relation between transversal displacement and the longitudinal strain is found. It is found that both the 1+1D and even the 1+2D problems for long travelling waves in nonlinear solids can be reduced to the Weierstrass equation for elliptic functions, which provide the solitary wave solutions as appropriate limits. We show that the accuracy in the boundary conditions on free lateral surfaces is of crucial importance for solution, derive the only equation for longitudinal nonlinear strain wave and show, that the equation has, amongst others, a bidirectional solitary wave solution, which lead us to successful physical experiments. We observed first the compression solitary wave in the
Oblique propagation of dust ion-acoustic solitary waves in a magnetized dusty pair-ion plasma
Misra, A P
2013-01-01
We study the linear and nonlinear properties of electrostatic waves in a magnetized pair-ion plasma with immobile positively charged dusts. For the obliquely propagating linear waves, a general dispersion relation is derived, from which it is shown that the low-frequency (in comparison with the negative-ion cyclotron frequency) long-wavelength "slow" and a "fast" modes can propagate as dust ion-acoustic (DIA) and dust ion-cyclotron (DIC)-like waves. The properties of these modes are analyzed with the effects of obliqueness of propagation $(\\theta)$, the negative to positive ion mass ratio $(m)$, the ratio of negative to positive ion temperatures $(T)$, the static magnetic field as well as the presence of charged dusts (characterized by the dust to negative-ion number density $\\delta$) in the plasma. In the nonlinear regime, a standard reductive perturbation technique is used to derive a Korteweg-de Vries (KdV) equation for the oblique DIA waves. We show that the KdV equation can admit either compressive or ra...
Multi-component optical solitary waves
DEFF Research Database (Denmark)
Kivshar, Y. S.; Sukhorukov, A. A.; Ostrovskaya, E. A.;
2000-01-01
We discuss several novel types of multi-component (temporal and spatial) envelope solitary waves that appear in fiber and waveguide nonlinear optics. In particular, we describe multi-channel solitary waves in bit-parallel-wavelength fiber transmission systems for highperformance computer networks......, multi-color parametric spatial solitary waves due to cascaded nonlinearities of quadratic materials, and quasiperiodic envelope solitons due to quasi-phase-matching in Fibonacci optical superlattices. (C) 2000 Elsevier Science B.V. All rights reserved....
Indian Academy of Sciences (India)
Aiyong Chen; Jibin Li; Chunhai Li; Yuanduo Zhang
2010-01-01
The bifurcation theory of dynamical systems is applied to an integrable non-linear wave equation. As a result, it is pointed out that the solitary waves of this equation evolve from bell-shaped solitary waves to W/M-shaped solitary waves when wave speed passes certain critical wave speed. Under different parameter conditions, all exact explicit parametric representations of solitary wave solutions are obtained.
Transversally periodic solitary gravity-capillary waves.
Milewski, Paul A; Wang, Zhan
2014-01-01
When both gravity and surface tension effects are present, surface solitary water waves are known to exist in both two- and three-dimensional infinitely deep fluids. We describe here solutions bridging these two cases: travelling waves which are localized in the propagation direction and periodic in the transverse direction. These transversally periodic gravity-capillary solitary waves are found to be of either elevation or depression type, tend to plane waves below a critical transverse period and tend to solitary lumps as the transverse period tends to infinity. The waves are found numerically in a Hamiltonian system for water waves simplified by a cubic truncation of the Dirichlet-to-Neumann operator. This approximation has been proved to be very accurate for both two- and three-dimensional computations of fully localized gravity-capillary solitary waves. The stability properties of these waves are then investigated via the time evolution of perturbed wave profiles. PMID:24399922
Solitary Waves in Relativistic Electromagnetic Plasma
Institute of Scientific and Technical Information of China (English)
XIE Bai-Song; HUA Cun-Cai
2005-01-01
Solitary waves in relativistic electromagnetic plasmas are obtained numerically. The longitudinal momentum of electrons has been taken into account in the problem. It is found that in the moving frame with electromagnetic field propagating the solitary waves can exist in both cases, where the vector potential frequency is larger or smaller than the plasma characteristic frequency.
Energy Technology Data Exchange (ETDEWEB)
Alam, M. S.; Uddin, M. J.; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Masud, M. M. [Department of Physics, Bangladesh University of Engineering and Technology, Dhaka (Bangladesh)
2014-09-01
Positron-acoustic (PA) solitary waves (SWs) and double layers (DLs) in four-component plasmas consisting of immobile positive ions, mobile cold positrons, and superthermal (kappa distributed) hot positrons and electrons are investigated both numerically and analytically by deriving Korteweg–de Vries (K-dV), modified K-dV (mK-dV), and Gardner equations along with their DLs solutions using the reductive perturbation method. It is examined that depending on the plasma parameters, the K-dV SWs, Gardner SWs, and DLs support either compressive or rarefactive structures, whereas mK-dV SWs support only compressive structure. It is also found that the presence of superthermal (kappa distributed) hot positrons and hot electrons significantly modify the basic features of PA SWs as well as PA DLs. Besides, the critical number density ratio of hot positrons and cold positrons play an important role in the polarity of PA SWs and DLs. The implications of our results in different space as well as laboratory plasma environments are briefly discussed.
Solitary waves in the granular chain
Sen, Surajit; Hong, Jongbae; Bang, Jonghun; Avalos, Edgar; Doney, Robert
2008-06-01
Solitary waves are lumps of energy. We consider the study of dynamical solitary waves, meaning cases where the energy lumps are moving, as opposed to topological solitary waves where the lumps may be static. Solitary waves have been studied in some form or the other for nearly 450 years. Subsequently, there have been many authoritative works on solitary waves. Nevertheless, some of the most recent studies reveal that these peculiar objects are far more complex than what we might have given them credit for. In this review, we introduce the physics of solitary waves in alignments of elastic beads, such as glass beads or stainless steel beads. We show that any impulse propagates as a new kind of highly interactive solitary wave through such an alignment and that the existence of these waves seems to present a need to re-examine the very definition of the concept of equilibrium. We further discuss the possibility of exploiting nonlinear properties of granular alignments to develop exciting technological applications.
Exact solitary wave solutions of nonlinear wave equations
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The hyperbolic function method for nonlinear wave equations ispresented. In support of a computer algebra system, many exact solitary wave solutions of a class of nonlinear wave equations are obtained via the method. The method is based on the fact that the solitary wave solutions are essentially of a localized nature. Writing the solitary wave solutions of a nonlinear wave equation as the polynomials of hyperbolic functions, the nonlinear wave equation can be changed into a nonlinear system of algebraic equations. The system can be solved via Wu Elimination or Grbner base method. The exact solitary wave solutions of the nonlinear wave equation are obtained including many new exact solitary wave solutions.
Conservative numerical methods for solitary wave interactions
Energy Technology Data Exchange (ETDEWEB)
Duran, A; Lopez-Marcos, M A [Departamento de Matematica Aplicada y Computacion, Facultad de Ciencias, Universidad de Valladolid, Paseo del Prado de la Magdalena s/n, 47005 Valladolid (Spain)
2003-07-18
The purpose of this paper is to show the advantages that represent the use of numerical methods that preserve invariant quantities in the study of solitary wave interactions for the regularized long wave equation. It is shown that the so-called conservative methods are more appropriate to study the phenomenon and provide a dynamic point of view that allows us to estimate the changes in the parameters of the solitary waves after the collision.
From solitary wave to traveling surge
Institute of Scientific and Technical Information of China (English)
宋礼庭
1995-01-01
The solution of kinetic Alfven wave under action of anomalous resistance has two branches: the slow wave, VP
Solitary Wave Propagation Influenced by Submerged Breakwater
Institute of Scientific and Technical Information of China (English)
王锦; 左其华; 王登婷
2013-01-01
The form of Boussinesq equation derived by Nwogu (1993) using velocity at an arbitrary distance and surface elevation as variables is used to simulate wave surface elevation changes. In the numerical experiment, water depth was divided into five layers with six layer interfaces to simulate velocity at each layer interface. Besides, a physical experiment was carried out to validate numerical model and study solitary wave propagation.“Water column collapsing”method (WCCM) was used to generate solitary wave. A series of wave gauges around an impervious breakwater were set-up in the flume to measure the solitary wave shoaling, run-up, and breaking processes. The results show that the measured data and simulated data are in good agreement. Moreover, simulated and measured surface elevations were analyzed by the wavelet transform method. It shows that different wave frequencies stratified in the wavelet amplitude spectrum. Finally, horizontal and vertical velocities of each layer interface were analyzed in the process of solitary wave propagation through submerged breakwater.
Solitary Wave Interactions in Granular Media
Institute of Scientific and Technical Information of China (English)
WEN Zhen-Ying; WANG Shun-Jin; ZHANG Xiu-Ming; LI Lei
2007-01-01
We numerically study the interactions of solitary waves in granular media, by considering a chain of beads, which repel upon contact via the Hertz-type potential, V ∝δn, with 5/2 ≤n≤3 and δ≥0,δbeing the bead-bead overlap. There are two collision types of solitary waves, overtaking collision and head-on collision, in the chain of beads. Our quantitative results show that after collision the large solitary wave gains energy and the small one loses energy for overtaking type while the large one loses energy, and the small one gains energy for head-on type. The scattering effects decrease with n for overtaking collision whereas increase with n for head-on collision.
ORBITAL STABILITY OF SOLITARY WAVES FOR GENERALIZED ZAKHAROV SYSTEM
Institute of Scientific and Technical Information of China (English)
2007-01-01
This paper considers the stability of the solitary waves for the generalized Zakharov system. By applying the abstract theory of Grillakis M. et al. and detailed spectral analysis, we obtain the stability of the solitary waves.
Energy Technology Data Exchange (ETDEWEB)
Ghosh, S. S., E-mail: sukti@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410218 (India); Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India)
2014-08-15
It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leads to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons.
Study on Solitary Waves of a General Boussinesq Model
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper, we employ the bifurcation method of dynamical systems to study the solitary waves and periodic waves of a generalized Boussinesq equations. All possible phase portraits in the parameter plane for the travelling wave systems are obtained. The possible solitary wave solutions, periodic wave solutions and cusp waves for the general Boussinesq type fluid model are also investigated.
Solitary waves on nonlinear elastic rods. II
DEFF Research Database (Denmark)
Sørensen, Mads Peter; Christiansen, Peter Leth; Lomdahl, P. S.;
1987-01-01
In continuation of an earlier study of propagation of solitary waves on nonlinear elastic rods, numerical investigations of blowup, reflection, and fission at continuous and discontinuous variation of the cross section for the rod and reflection at the end of the rod are presented. The results...
Solitary Wave Solutions for Zoomeron Equation
Directory of Open Access Journals (Sweden)
Amna IRSHAD
2013-04-01
Full Text Available Tanh-Coth Method is applied to find solitary wave solutions of the Zoomeron equation which is of extreme importance in mathematical physics. The proposed scheme is fully compatible with the complexity of the problem and is highly efficient. Moreover, suggested combination is capable to handle nonlinear problems of versatile physical nature.
Scattering of solitary waves in granular media
Vergara, Lautaro
2005-01-01
A detailed numerical study of the scattering of solitary waves by a barrier, in a granular media with Hertzian contact, shows the existence of secondary multipulse structures generated at the interface of two "sonic vacua", which have a similar structure as the one previously found by Nesterenko and coworkers.
Uphill solitary waves in granular flows
Martínez, E.; Pérez-Penichet, C.; Sotolongo-Costa, O.; Ramos, O.; Måløy, K. J.; Douady, S.; Altshuler, E.
2007-03-01
We have experimentally observed uphill solitary waves in the surface flow on a granular material. A heap is constructed by injecting sand between two vertical glass plates separated by a distance much larger than the average grain size, with an open boundary. As the heap reaches the open boundary, solitary fluctuations appear on the flowing layer and move “up the hill” (i.e., against the direction of the flow). We explain the phenomenon in the context of stop-and-go traffic models.
Frustrated Brownian Motion of Nonlocal Solitary Waves
International Nuclear Information System (INIS)
We investigate the evolution of solitary waves in a nonlocal medium in the presence of disorder. By using a perturbational approach, we show that an increasing degree of nonlocality may largely hamper the Brownian motion of self-trapped wave packets. The result is valid for any kind of nonlocality and in the presence of nonparaxial effects. Analytical predictions are compared with numerical simulations based on stochastic partial differential equations.
Weierstrass's criterion and compact solitary waves
Destrade, Michel; Saccomandi, Giuseppe
2007-01-01
Weierstrass's theory is a standard qualitative tool for single degree of freedom equations, used in classical mechanics and in many textbooks. In this Brief Report we show how a simple generalization of this tool makes it possible to identify some differential equations for which compact and even semicompact traveling solitary waves exist. In the framework of continuum mechanics, these differential equations correspond to bulk shear waves for a special class of constitutive laws.
Bright Solitary Waves in Malignant Gliomas
Pérez-García, Víctor M.; Calvo, Gabriel F.; Belmonte-Beitia, Juan; Diego, D.; Pérez-Romasanta, Luis
2011-01-01
We put forward a nonlinear wave model describing the fundamental physio-pathologic features of an aggressive type of brain tumors: glioblastomas. Our model accounts for the invasion of normal tissue by a proliferating and propagating rim of active glioma cancer cells in the tumor boundary and the subsequent formation of a necrotic core. By resorting to numerical simulations, phase space analysis and exact solutions, we prove that bright solitary tumor waves develop in such systems.
The lifecycle of axisymmetric internal solitary waves
Directory of Open Access Journals (Sweden)
J. M. McMillan
2010-09-01
Full Text Available The generation and evolution of solitary waves by intrusive gravity currents in an approximate two-layer fluid with equal upper- and lower-layer depths is examined in a cylindrical geometry by way of theory and numerical simulations. The study is limited to vertically symmetric cases in which the density of the intruding fluid is equal to the average density of the ambient. We show that even though the head height of the intrusion decreases, it propagates at a constant speed well beyond 3 lock radii. This is because the strong stratification at the interface supports the formation of a mode-2 solitary wave that surrounds the intrusion head and carries it outwards at a constant speed. The wave and intrusion propagate faster than a linear long wave; therefore, there is strong supporting evidence that the wave is indeed nonlinear. Rectilinear Korteweg-de Vries theory is extended to allow the wave amplitude to decay as r^{-p} with p=½ and the theory is compared to the observed waves to demonstrate that the width of the wave scales with its amplitude. After propagating beyond 7 lock radii the intrusion runs out of fluid. Thereafter, the wave continues to spread radially at a constant speed, however, the amplitude decreases sufficiently so that linear dispersion dominates and the amplitude decays with distance as r^{-1}.
Dynamics of Gravity-Capillary Solitary Waves in Deep Water
Wang, Zhan
2012-01-01
The dynamics of solitary gravity-capillary water waves propagating on the surface of a three-dimensional fluid domain is studied numerically. In order to accurately compute complex time dependent solutions, we simplify the full potential flow problem by taking a cubic truncation of the scaled Dirichlet-to-Neumann operator for the normal velocity on the free surface. This approximation agrees remarkably well with the full equations for the bifurcation curves, wave profiles and the dynamics of solitary waves for a two-dimensional fluid domain. Fully localised solitary waves are then computed in the three-dimensional problem and the stability and interaction of both line and localized solitary waves are investigated via numerical time integration of the equations. The solitary wave branches are indexed by their finite energy at small amplitude, and the dynamics of the solitary waves is complex involving nonlinear focussing of wave packets, quasi-elastic collisions, and the generation of propagating, spatially lo...
Numerical Study on Breaking Criteria for Solitary Waves
Institute of Scientific and Technical Information of China (English)
Chung-ren CHOU; Ruey-syan SHIH; John Z. YIM
2003-01-01
Studies of the breaking criteria for solitary waves on a slope are presented in this paper. The boundary element method is used to model the processes of shoaling and breaking of solitary waves on various slopes. Empirical formulae that can be used to characterize the breaking of solitary waves are presented. These include the breaking index, the wave height, the water depth, and the maximum particle velocity at the point of breaking. Comparisons with the results of other researches are given.
Paul, Ashesh
2016-01-01
Employing the Sagdeev pseudo-potential technique the ion acoustic solitary structures have been investigated in an unmagnetized collisionless plasma consisting of adiabatic warm ions, nonthermal electrons and isothermal positrons. The qualitatively different compositional parameter spaces clearly indicate the existence domains of solitons and double layers with respect to any parameter of the present plasma system. The present system supports the negative potential double layer which always restricts the occurrence of negative potential solitons. The system also supports positive potential double layers when the ratio of the average thermal velocity of positrons to that of electrons is less than a critical value. However, there exists a parameter regime for which the positive potential double layer is unable to restrict the occurrence of positive potential solitary waves and in this region of the parameter space, there exist positive potential solitary waves after the formation of a positive potential double ...
Solitary Wave and Wave Front as Viewed From Curvature
Institute of Scientific and Technical Information of China (English)
LIUShi-Kuo; FUZun-Tao; LIUShi-Da; LIANGFu-Ming; XINGuo-Jun
2004-01-01
The solitary wave and wave front are two important behaviors of nonlinear evolution equations. Geometrically, solitary wave and wave front are all plane curve. In this paper, they can be represented in terms of curvature c(s),which varies with arc length s. For solitary wave when s→±∞, then its curvature c(s) approaches zero, and whens = 0, the curvature c(s) reaches its maximum. For wave front, when s→±∞, then its curvature c(s) approaches zero,and when s = 0, the curvature c(s) is still zero, but c'(s)≠0. That is, s = 0 is a turning point. When c(s) is given,the variance at some point (x, y) in stream line with arc length s satisfies a 2-order linear variable-coeffcient ordinary differential equation. From this equation, it can be determined qualitatively whether the given curvature is a solitary wave or wave front.
Solitary Wave and Wave Front as Viewed From Curvature
Institute of Scientific and Technical Information of China (English)
LIU Shi-Kuo; FU Zun-Tao; LIU Shi-Da; LIANG Fu-Ming; XIN Guo-Jun
2004-01-01
The solitary wave and wave front are two important behaviors of nonlinear evolution equations. Geometri cally, solitary wave and wave front are all plane curve. In this paper, they can be represented in terms of curvature c(s), which varies with arc length s. For solitary wave when s →±∞, then its curvature c(s) approaches zero, and when s = 0, the curvature c(s) reaches its maximum. For wave front, when s →±∞, then its curvature c(s) approaches zero, and when s = 0, the curvature c(s) is still zero, but c'(s) ≠ 0. That is, s = 0 is a turning point. When c(s) is given, the variance at some point (x, y) in stream line with arc length s satisfies a 2-order linear variable-coefficient ordinary differential equation. From this equation, it can be determined qualitatively whether the given curvature is a solitary wave or wave front.
Dust acoustic solitary and shock excitations in a Thomas-Fermi magnetoplasma
Energy Technology Data Exchange (ETDEWEB)
Rahim, Z.; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan)
2014-07-15
The linear and nonlinear properties of dust-acoustic waves are investigated in a collisionless Thomas-Fermi magnetoplasma, whose constituents are electrons, ions, and negatively charged dust particles. At dust time scale, the electron and ion number densities follow the Thomas-Fermi distribution, whereas the dust component is described by the classical fluid equations. A linear dispersion relation is analyzed to show that the wave frequencies associated with the upper and lower modes are enhanced with the variation of dust concentration. The effect of the latter is seen more strongly on the upper mode as compared to the lower mode. For nonlinear analysis, we obtain magnetized Korteweg-de Vries (KdV) and Zakharov-Kuznetsov (ZK) equations involving the dust-acoustic solitary waves in the framework of reductive perturbation technique. Furthermore, the shock wave excitations are also studied by allowing dissipation effects in the model, leading to the Korteweg-de Vries-Burgers (KdVB) and ZKB equations. The analysis reveals that the dust-acoustic solitary and shock excitations in a Thomas-Fermi plasma are strongly influenced by the plasma parameters, e.g., dust concentration, dust temperature, obliqueness, magnetic field strength, and dust fluid viscosity. The present results should be important for understanding the solitary and shock excitations in the environments of white dwarfs or supernova, where dust particles can exist.
Solitary waves and their linear stability in nonlinear lattices
Hwang, Guenbo; Yang, Jianke
2011-01-01
Solitary waves in a general nonlinear lattice are discussed, employing as a model the nonlinear Schr\\"odinger equation with a spatially periodic nonlinear coefficient. An asymptotic theory is developed for long solitary waves, that span a large number of lattice periods. In this limit, the allowed positions of solitary waves relative to the lattice, as well as their linear stability properties, hinge upon a certain recurrence relation which contains information beyond all orders of the usual two-scale perturbation expansion. It follows that only two such positions are permissible, and of those two solitary waves, one is linearly stable and the other unstable. For a cosine lattice, in particular, the two possible solitary waves are centered at a maximum or minimum of the lattice, with the former being stable, and the analytical predictions for the associated linear stability eigenvalues are in excellent agreement with numerical results. Furthermore, a countable set of multi-solitary-wave bound states are const...
On the solitary wave paradigm for tsunamis
DEFF Research Database (Denmark)
Madsen, Per A.; Fuhrman, David R.; Schäffer, Hemming Andreas
2008-01-01
the evolution of initial rectangular shaped humps of water propagating large distances over a constant depth. The objective is to clarify under which circumstances the front of the wave can develop into an undular bore with a leading soliton. In this connection we discuss and test various measures...... of long waves into shorter waves, which has been observed e.g. in connection with the Indian Ocean tsunami in 2004. This happens if the front of the tsunami becomes sufficently steep, and as a result the front turns into an undular bore. We discuss the importance of these very short waves in connection......Since the 1970s, solitary waves have commonly been used to model tsunamis especially in experimental and mathematical studies. Unfortunately, the link to geophysical scales is not well established, and in this work we question the geophysical relevance of this paradigm. In part 1, we simulate...
Stable complex solitary waves of Sasa Satsuma equation
Indian Academy of Sciences (India)
Sasanka Ghosh
2001-11-01
Existence of a new class of complex solitary waves is shown for Sasa Satsuma equation. These solitary waves are found to be stable in a certain domain of the parameter and become chaotic if the parameter exceeds the value 2.4. Signiﬁcantly, the complex solitary waves propagate at higher bit rate over the most stable solitons under the same conditions of the input parameters.
Effect of Nonlinearity on Scattering Dynamics of Solitary Waves
Institute of Scientific and Technical Information of China (English)
WEN Zhen-Ying; ZHAO Hong; WANG Shun-Jin; ZHANG Xiu-Ming
2006-01-01
@@ We discuss the effect of nonlinearity on the scattering dynamics of solitary waves. The pure nth power model with the interaction potential V(x) = xn/n is present, which is a paradigm model in the study of solitary waves. The dependence of the scattering property on nonlinearity is closely related to the topological structures of the solitary waves. Moreover, for one of the four collision types, the rates of energy loss increase with the strength of nonlinearity and would reach 1 at n≥10, which means that the two solitary waves would become of fragments completely after the collision.
Acoustics waves and oscillations
Sen, S.N.
2013-01-01
Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...
Paul, Ashesh; Das, K P
2016-01-01
The purpose of this paper is to extend the recent work of Paul & Bandyopadhyay [Astrophys. Space Sci. 361, 172(2016)] on the existence of different dust ion acoustic solitary structures in an unmagnetized collisionless dusty plasma consisting of negatively charged static dust grains, adiabatic warm ions, nonthermal electrons and isothermal positrons in a more generalized form by considering nonthermal positrons instead of isothermal positrons. The present system supports both positive and negative potential double layers, coexistence of solitary waves of both polarities and positive potential supersolitons. The qualitative and the quantitative changes in existence domains of different solitary structures which occur for the presence of nonthermal positrons have been presented in comparison with the results of Paul & Bandyopadhyay [Astrophys. Space Sci. 361, 172(2016)]. The formation of supersoliton structures and their limitations have been analyzed with the help of phase portraits of the dynamical sy...
Localization and solitary waves in solid mechanics
Champneys, A R; Thompson, J M T
1999-01-01
This book is a collection of recent reprints and new material on fundamentally nonlinear problems in structural systems which demonstrate localized responses to continuous inputs. It has two intended audiences. For mathematicians and physicists it should provide useful new insights into a classical yet rapidly developing area of application of the rich subject of dynamical systems theory. For workers in structural and solid mechanics it introduces a new methodology for dealing with structural localization and the related topic of the generation of solitary waves. Applications range from classi
Dark Spatial Solitary Wave Due to Cascaded x(2) Nonlinearity
Institute of Scientific and Technical Information of China (English)
GAO Guan-Qie; CHEN Xian-Feng; CHEN Yu-Ping; WANG Fei-Yu; XIA Yu-Xing
2004-01-01
The formation of the dark spatial solitary wave in cascaded second harmonic generation processes is numerically studied based on the nonlinear-coupled equations. It is shown that the solitary wave exists when the effective three-order nonlinearity induced by cascaded second-order nonlinearity is negative.
Solitary waves in asymmetric electron-positron-ion plasmas
Lu, Ding; Li, Zi-Liang; Xie, Bai-Song
2015-10-01
> By solving the coupled equations of the electromagnetic field and electrostatic potential, we investigate solitary waves in an asymmetric electron-positron plasma and/or electron-positron-ion plasmas with delicate features. It is found that the solutions of the coupled equations can capture multipeak structures of solitary waves in the case of cold plasma, which are left out by using the long-wavelength approximation. By considering the effect of ion motion with respect to non-relativistic and ultra-relativistic temperature plasmas, we find that the ions' mobility can lead to larger-amplitude solitary waves; especially, this becomes more obvious for a high-temperature plasma. The effects of asymmetric temperature between electrons and positrons and the ion fraction on the solitary waves are also studied and presented. It is shown that the amplitudes of solitary waves decrease with positron temperature in asymmetric temperature electron-positron plasmas and decrease also with ion concentration.
Impact induced solitary wave propagation through a woodpile structure
Kore, R.; Waychal, A.; Agarwal, S.; Yadav, P.; Uddin, Ahsan; Sahoo, N.; Shelke, A.
2016-02-01
In this paper, we investigate solitary wave propagation through a one-dimensional woodpile structure excited by low and high velocity impact. Woodpile structures are a sub-class of granular metamaterial, which supports propagation of nonlinear waves. Hertz contact law governs the behavior of the solitary wave propagation through the granular media. Towards an experimental study, a woodpile structure was fabricated by orthogonally stacking cylindrical rods. A shock tube facility has been developed to launch an impactor on the woodpile structure at a velocity of 30 m s-1. Embedded granular chain sensors were fabricated to study the behavior of the solitary wave. The impact induced stress wave is studied to investigate solitary wave parameters, i.e. contact force, contact time, and solitary wave velocity. With the aid of the experimental setup, numerical simulations, and a theoretical solution based on the long wavelength approximation, formation of the solitary wave in the woodpile structure is validated to a reasonable degree of accuracy. The nondispersive and compact supported solitary waves traveling at sonic wave velocity offer unique properties that could be leveraged for application in nondestructive testing and structural health monitoring.
Interaction of solitary waves in magnetized warm dusty plasmas with dust charging effects
Institute of Scientific and Technical Information of China (English)
Xue Ju-Kui
2006-01-01
In consideration of adiabatic dust charge variation, the combined effect of the external magnetized field and the dust temperature on head-on collision of the three-dimensional dust acoustic solitary waves is investigated. By using the extended Poincaré-Lighthill-Kuo method, the phase shifts and the trajectories of two solitons after the collision are obtained. The effects of the magnitude and the obliqueness of the external magnetic field and the dust temperature on the solitary wave collisions are discussed in detail.
Analytical study of dissipative solitary waves
Energy Technology Data Exchange (ETDEWEB)
Dini, Fatemeh [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Emamzadeh, Mehdi Molaie [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Khorasani, Sina [School of Electrical Engineering, Sharif University of Technology, PO Box 11365-363, Tehran (Iran, Islamic Republic of); Bobin, Jean Louis [Universite Pierre et Marie Curie, Paris (France); Amrollahi, Reza [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sodagar, Majid [School of Electrical Engineering, Sharif University of Technology, PO Box 11365-363, Tehran (Iran, Islamic Republic of); Khoshnegar, Milad [School of Electrical Engineering, Sharif University of Technology, PO Box 11365-363, Tehran (Iran, Islamic Republic of)
2008-02-15
In this paper, the analytical solution to a new class of nonlinear solitons is presented with cubic nonlinearity, subject to a dissipation term arising as a result of a first-order derivative with respect to time, in the weakly nonlinear regime. Exact solutions are found using the combination of the perturbation and Green's function methods up to the third order. We present an example and discuss the asymptotic behavior of the Green's function. The dissipative solitary equation is also studied in the phase space in the non-dissipative and dissipative forms. Bounded and unbounded solutions of this equation are characterized, yielding an energy conversation law for non-dissipative waves. Applications of the model include weakly nonlinear solutions of terahertz Josephson plasma waves in layered superconductors and ablative Rayleigh-Taylor instability.
Analytical study of dissipative solitary waves
International Nuclear Information System (INIS)
In this paper, the analytical solution to a new class of nonlinear solitons is presented with cubic nonlinearity, subject to a dissipation term arising as a result of a first-order derivative with respect to time, in the weakly nonlinear regime. Exact solutions are found using the combination of the perturbation and Green's function methods up to the third order. We present an example and discuss the asymptotic behavior of the Green's function. The dissipative solitary equation is also studied in the phase space in the non-dissipative and dissipative forms. Bounded and unbounded solutions of this equation are characterized, yielding an energy conversation law for non-dissipative waves. Applications of the model include weakly nonlinear solutions of terahertz Josephson plasma waves in layered superconductors and ablative Rayleigh-Taylor instability
DEFF Research Database (Denmark)
Dühring, Maria Bayard
The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...
The solitary electromagnetic waves in the graphene superlattice
International Nuclear Information System (INIS)
d’Alembert equation written for the electromagnetic waves propagating in the graphene superlattice is analyzed. The possibility of the propagation of the solitary electromagnetic waves in the graphene superlattice is discussed. The amplitude and the width of the electromagnetic pulse are calculated. The drag current induced by such wave across the superlattice axis is investigated. The numerical estimate of the charge dragged by the solitary wave is made.
The solitary electromagnetic waves in the graphene superlattice
Energy Technology Data Exchange (ETDEWEB)
Kryuchkov, Sergey V., E-mail: svkruchkov@yandex.ru [Volgograd State Socio-Pedagogical University, V.I. Lenin Avenue, 27, Volgograd 400005 (Russian Federation); Volgograd State Technical University, V.I. Lenin Avenue, 28, Volgograd 400005 (Russian Federation); Kukhar' , Egor I., E-mail: eikuhar@yandex.ru [Volgograd State Socio-Pedagogical University, V.I. Lenin Avenue, 27, Volgograd 400005 (Russian Federation)
2013-01-01
d'Alembert equation written for the electromagnetic waves propagating in the graphene superlattice is analyzed. The possibility of the propagation of the solitary electromagnetic waves in the graphene superlattice is discussed. The amplitude and the width of the electromagnetic pulse are calculated. The drag current induced by such wave across the superlattice axis is investigated. The numerical estimate of the charge dragged by the solitary wave is made.
Deep-water internal solitary waves near critical density ratio
Agafontsev, D S; Kuznetsov, E A
2005-01-01
Bifurcations of solitary waves propagating along the interface between two ideal fluids are considered. The study is based on a Hamiltonian approach. It concentrates on values of the density ratio close to a critical one, where the supercritical bifurcation changes to the subcritical one. As the solitary wave velocity approaches the minimum phase velocity of linear interfacial waves (the bifurcation point), the solitary wave solutions transform into envelope solitons. In order to describe their behavior and bifurcations, a generalized nonlinear Schr\\"{o}dinger equation describing the behavior of solitons and their bifurcations is derived. In comparison with the classical NLS equation this equation takes into account three additional nonlinear terms: the so-called Lifshitz term responsible for pulse steepening, a nonlocal term analogous to that first found by Dysthe for gravity waves and the six-wave interaction term. We study both analytically and numerically two solitary wave families of this equation for va...
Gokhberg, M. B.
1983-07-01
Experiments devoted to acoustic action on the atmosphere-magnetosphere-ionosphere system using ground based strong explosions are reviewed. The propagation of acoustic waves was observed by ground observations over 2000 km in horizontal direction and to an altitude of 200 km. Magnetic variations up to 100 nT were detected by ARIEL-3 satellite near the epicenter of the explosion connected with the formation of strong field aligned currents in the magnetosphere. The enhancement of VLF emission at 800 km altitude is observed.
Electromagnetic solitary waves in magnetized plasmas
International Nuclear Information System (INIS)
A Hamiltonian formulation, in terms of noncanonical Poisson bracket, is presented for a nonlinear fluid system that includes reduced magnetohydrodynamics and the Hasegawa-Mima equation as limiting cases. The single-helicity and axisymmetric versions possess three nonlinear Casimir invariants, from which a generalized potential can be constructed. Variation of the generalized potential yields a description of exact nonlinear stationary states. The new equilibria, allowing for plasma flow as well as partial electron adiabaticity, are distinct from those found in conventional magnetohydrodynamic theory. They differ from electrostatic stationary states in containing plasma current and magnetic field excitation. One class of steady-state solutions is shown to provide a simple electromagnetic generalization of drift-solitary waves
Quintic Nonlinearity Induced Solitary Waves in Plasma Physics
Institute of Scientific and Technical Information of China (English)
刘红; 贺贤土; 楼森岳
2002-01-01
The quintic nonlinearity is important in the study of the nonlinear interaction between Langmuir waves and electrons in plasma. Using the pseudoenergy approach, five types of solitary wave solution are obtained explicitly.Only one of these is the modification of the soliton of the cubic nonlinear Schrodinger equation and can be treated perturbatively. However, other four types of solitary wave solution are all induced by the quintic nonlinearity and cannot be treated perturbatively from the solutions of the cubic nonlinear Schrodinger equation.
Efficient computation of capillary-gravity generalized solitary waves
Dutykh, Denys; Duran, Angel
2015-01-01
This paper is devoted to the computation of capillary-gravity solitary waves of the irrotational incompressible Euler equations with free surface. The numerical study is a continuation of a previous work in several points: an alternative formulation of the Babenko-type equation for the wave profiles, a detailed description of both the numerical resolution and the analysis of the internal flow structure under a solitary wave. The numerical code used in this study is provided in open source for interested readers.
The propagation of solitary waves in clouds of Bose- Einstein condensed atoms
Institute of Scientific and Technical Information of China (English)
Ao Sheng-Mei; Yan Jia-Ren
2006-01-01
The propagation of solitary waves in clouds of Boseted trap is solved analytically, and a solitary-wave solution is obtained in the low-density case without neglecting the effect of the interatomic interaction on the transverse function. It is shown that this effect leads to the velocity of the solitary wave slowing down and the profile of the solitary wave widening.
Solitary Wave in One-dimensional Buckyball System at Nanoscale
Xu, Jun; Zheng, Bowen; Liu, Yilun
2016-01-01
We have studied the stress wave propagation in one-dimensional (1-D) nanoscopic buckyball (C60) system by molecular dynamics (MD) simulation and quantitative modeling. Simulation results have shown that solitary waves are generated and propagating in the buckyball system through impacting one buckyball at one end of the buckyball chain. We have found the solitary wave behaviors are closely dependent on the initial temperature and impacting speed of the buckyball chain. There are almost no dispersion and dissipation of the solitary waves (stationary solitary wave) for relatively low temperature and high impacting speed. While for relatively high temperature and low impacting speed the profile of the solitary waves is highly distorted and dissipated after propagating several tens of buckyballs. A phase diagram is proposed to describe the effect of the temperature and impacting speed on the solitary wave behaviors in buckyball system. In order to quantitatively describe the wave behavior in buckyball system, a simple nonlinear-spring model is established, which can describe the MD simulation results at low temperature very well. The results presented in this work may lay a solid step towards the further understanding and manipulation of stress wave propagation and impact energy mitigation at nanoscale. PMID:26891624
Planar and Nonplanar Solitary Waves in a Four-Component Relativistic Degenerate Dense Plasma
Directory of Open Access Journals (Sweden)
M. R. Hossen
2014-01-01
degenerate electrons, nonrelativistic degenerate ions, and arbitrarily charged static heavy ions has been investigated theoretically. The Korteweg-de Vries (K-dV equation has been derived by employing the reductive perturbation method. Their solitary wave solution is obtained and numerically analyzed in case of both planar and nonplanar (cylindrical and spherical geometry. It has been observed that the ion-acoustic (IA and modified ion-acoustic (mIA solitary waves have been significantly changed due to the effects of degenerate plasma pressure and number densities of the arbitrarily charged heavy ions. It has been also found that properties of planar K-dV solitons are quite different from those of nonplanar K-dV solitons. There are numerous variations in case of mIA solitary waves due to the polarity of heavy ions. The basic features and the underlying physics of IA and mIA solitary waves, which are relevant to some astrophysical compact objects, are briefly discussed.
Directory of Open Access Journals (Sweden)
Kazantseva E.V.
2015-01-01
Full Text Available In a model which describes asymmetric oppositely directed nonlinear coupler it was observed in numerical simulations a phenomenon of solitary wave generation from the input constant continuous wave set at the entrance of a waveguide with negative refraction. The period of solitary wave formation decreases with increase of the continuum wave amplitude.
Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells
VIJ, JAGDISH; Song, Jang-Kun
2008-01-01
PUBLISHED Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells controlled by surface anchoring of the alignment layers is investigated for different conditions of alignment on the two opposite surfaces. We show that the critical field Ec, where the speed of the solitary wave becomes zero, is finite for asymmetric alignment on two surfaces. We also show that the polar anchoring energy difference (Deltawp) between the alignment layers can be calculated by measur...
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Gadadhar; Maitra, Sarit [Department of Mathematics, National Institute of Technology Durgapur, Durgapur (India)
2015-04-15
Sagdeev's pseudopotential method is used to study small as well as arbitrary amplitude dust acoustic solitons in a dusty plasma with kappa distributed electrons and ions with dust grains having power law size distribution. The existence of potential well solitons has been shown for suitable parametric region. The criterion for existence of soliton is derived in terms of upper and lower limit for Mach numbers. The numerical results show that the size distribution can affect the existence as well as the propagation characteristics of the dust acoustic solitons. The effect of kappa distribution is also highlighted.
Indian Academy of Sciences (India)
S N Paul; S Chattopadhyaya; S K Bhattacharya; B Bera
2003-06-01
Using the pseudopotential method, theoretical investigation has been made on the ﬁrst-order Korteweg-deVries ion-acoustic solitons in a multicomponent plasma consisting of warm positive ions, negative ions and isothermal electrons. The effects of electron-inertia and drift motion of the ions on the amplitudes and widths of the solitons have been studied in a plasma having (H+, Cl-), (H+, O-), (He+, H-) and (He+, O-) ions. Ion-acoustic double-layers have also been investigated for such plasmas. It has been found that drift velocity and electron-inertia have signiﬁcant contribution on the formation of double-layers in multicomponent plasma.
Multi-valued solitary waves in multidimensional soliton systems
Institute of Scientific and Technical Information of China (English)
Zheng Chun-Long; Chen Li-Qun; Zhang Jie-Fang
2004-01-01
Considering that folded phenomena are rather universal in nature and some arbitrary functions can be included in the exact excitations of many (2+1)-dimensional soliton systems, we use adequate multivalued functions to construct folded solitary structures in multi-dimensions. Based on some interesting variable separation results in the literature, a common formula with arbitrary functions has been derived for suitable physical quantities of some significant(2+1)-dimensional soliton systems like the generalized Ablowitz-Kaup-Newell-Segur (GAKNS) model, the generalized Nizhnik-Novikov-Veselov (GNNV) system and the new (2+1)-dimensional long dispersive wave (NLDW) system. Then a new special type of two-dimensional solitary wave structure, i.e. the folded solitary wave and foldon, is obtained. The novel structure exhibits interesting features not found in the single valued solitary excitations.
Diffractons: Solitary Waves Created by Diffraction in Periodic Media
Ketcheson, David I.
2015-03-31
A new class of solitary waves arises in the solution of nonlinear wave equations with constant impedance and no dispersive terms. These solitary waves depend on a balance between nonlinearity and a dispersion-like effect due to spatial variation in the sound speed of the medium. A high-order homogenized model confirms this effective dispersive behavior, and its solutions agree well with those obtained by direct simulation of the variable-coefficient system. These waves are observed to be long-time stable, globally attracting solutions that arise in general as solutions to nonlinear wave problems with periodically varying sound speed. They share some properties with known classes of solitary waves but possess important differences as well.
Relativistic solitary waves modulating long laser pulses in plasmas
Sánchez-Arriaga, G; Lefebvre, E
2011-01-01
This article discusses the existence of solitary electromagnetic waves trapped in a self-generated Langmuir wave and embedded in an infinitely long circularly polarized electromagnetic wave propagating through a plasma. From the mathematical point of view they are exact solutions of the 1-dimensional relativistic cold fluid plasma model with nonvanishing boundary conditions. Under the assumption of traveling wave solutions with velocity $V$ and vector potential frequency $\\omega$, the fluid model is reduced to a Hamiltonian system. The solitary waves are homoclinic (grey solitons) or heteroclinic (dark solitons) orbits to fixed points. By using a dynamical systems description of the Hamiltonian system and a spectral method, we identify a great variety of solitary waves, including asymmetric ones, discuss their disappearance for certain parameter values, and classify them according to: (i) grey or dark character, (ii) the number of humps of the vector potential envelope and (iii) their symmetries. The solution...
Developing Serpent-Type Wave Generators to Create Solitary Wave Simulations with BEM
Institute of Scientific and Technical Information of China (English)
Wen-Kai WENG; Ruey-Syan SHIH; Chung-Ren CHOU
2013-01-01
Developing serpent-type wave generators to generate solitary waves in a 3D-basin was investigated in this study. Based on the Lagrangian description with time-marching procedures and finite differences of the time derivative, a 3D multiple directional wave basin with multidirectional piston wave generators was developed to simulate ocean waves by using BEM with quadrilateral elements, and to simulate wave-caused problems with fully nonlinear water surface conditions. The simulations of perpendicular solitary waves were conducted in the first instance to verify this scheme. Furthermore, the comparison of the waveform variations confirms that the estimation of 3D solitary waves is a feasible scheme.
Adiabatic trapping in coupled kinetic Alfven-acoustic waves
Energy Technology Data Exchange (ETDEWEB)
Shah, H. A.; Ali, Z. [Department of Physics, G.C. University, 54000 Lahore (Pakistan); Masood, W. [COMSATS, Institute of Information Technology, Park Road, Chak Shahzad, Islamabad 44000 (Pakistan); National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Theoretical Plasma Physics Division, P. O. Nilore, Islamabad (Pakistan)
2013-03-15
In the present work, we have discussed the effects of adiabatic trapping of electrons on obliquely propagating Alfven waves in a low {beta} plasma. Using the two potential theory and employing the Sagdeev potential approach, we have investigated the existence of arbitrary amplitude coupled kinetic Alfven-acoustic solitary waves in both the sub and super Alfvenic cases. The results obtained have been analyzed and presented graphically and can be applied to regions of space where the low {beta} assumption holds true.
Energy Technology Data Exchange (ETDEWEB)
Ali Shan, S. [Theoretical Plasma Physics Division, PINSTECH, Nilore, 44000 Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, 44000 Islamabad (Pakistan); Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad (Pakistan); El-Tantawy, S. A.; Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt)
2013-08-15
Arbitrary amplitude ion-acoustic waves in an unmagnetized plasma consisting of cold positive ions, superthermal electrons, and positrons beam are reported. The basic set of fluid equations is reduced to an energy-balance like equation. The latter is numerically analyzed to examine the existence regions for solitary and shock waves. It is found that only solitary waves can propagate, however, the model cannot support shocks. The effects of superthermality and beam parameters (via, positrons concentration and streaming velocity) on the existence region, as well as solitary wave profile have been discussed.
Numerical Simulation of Cylindrical Solitary Waves in Periodic Media
Quezada de Luna, Manuel
2013-07-14
We study the behavior of nonlinear waves in a two-dimensional medium with density and stress relation that vary periodically in space. Efficient approximate Riemann solvers are developed for the corresponding variable-coefficient first-order hyperbolic system. We present direct numerical simulations of this multiscale problem, focused on the propagation of a single localized perturbation in media with strongly varying impedance. For the conditions studied, we find little evidence of shock formation. Instead, solutions consist primarily of solitary waves. These solitary waves are observed to be stable over long times and to interact in a manner approximately like solitons. The system considered has no dispersive terms; these solitary waves arise due to the material heterogeneity, which leads to strong reflections and effective dispersion.
Measurement of velocity field in parametrically excited solitary waves
Gordillo, Leonardo
2014-01-01
Paramerically excited solitary waves emerge as localized structures in high-aspect-ratio free surfaces subject to vertical vibrations. Herein, we provide the first experimental characterization of the hydrodynamics of thess waves using Particle Image Velocimetry. We show that the underlying velocity field of parametrically excited solitary waves is mainly composed by an oscillatory velocity field. Our results confirm the accuracy of Hamiltonian models with added dissipation in describing this field. Remarkably, our measurements also uncover the onset of a streaming velocity field which is shown to be as important as other crucial nonlinear terms in the current theory. The observed streaming pattern is particularly interesting due to the presence of oscillatory meniscii.
Axisymmetric solitary waves on the surface of a ferrofluid
Bourdin, Elise; Falcon, Eric
2010-01-01
We report the first observation of axisymmetric solitary waves on the surface of a cylindrical magnetic fluid layer surrounding a current-carrying metallic tube. According to the ratio between the magnetic and capillary forces, both elevation and depression solitary waves are observed with profiles in good agreement with theoretical predictions based on the magnetic analogue of the Korteweg-deVries equation. We also report the first measurements of the velocity and the dispersion relation of axisymmetric linear waves propagating on the cylindrical ferrofluid layer that are found in good agreement with theoretical predictions.
Bifurcation and solitary waves of the nonlinear wave equation with quartic polynomial potential
Institute of Scientific and Technical Information of China (English)
化存才; 刘延柱
2002-01-01
For the nonlinear wave equation with quartic polynomial potential, bifurcation and solitary waves are investigated. Based on the bifurcation and the energy integral of the two-dimensional dynamical system satisfied by the travelling waves, it is very interesting to find different sufficient and necessary conditions in terms of the bifurcation parameter for the existence and coexistence of bright, dark solitary waves and shock waves. The method of direct integration is developed to give all types of solitary wave solutions. Our method is simpler than other newly developed ones. Some results are similar to those obtained recently for the combined KdV-mKdV equation.
Solitary waves in a nonintegrable Fermi-Pasta-Ulam chain
Truskinovsky, Lev; Vainchtein, Anna
2014-10-01
We present a family of exact solutions describing discrete solitary waves in a nonintegrable Fermi-Pasta-Ulam chain. The family is sufficiently rich to cover the whole spectrum of known behaviors from delocalized quasicontinuum waves moving with near-sonic velocities to highly localized anticontinuum excitations with only one particle moving at a time.
Solitary Wave in Linear ODE with Variable Coefficients
Institute of Scientific and Technical Information of China (English)
LIU Shi-Da; FU Zun-Tao; LIU Shi-Kuo; XIN Guo-Jun; LIANG Fu-Ming; FENG Bei-Ye
2003-01-01
In this paper, the linear ordinary differential equations with variable coefficients are obtained from thecontrolling equations satisfied by wavelet transform or atmospheric internal gravity waves, and these linear equationscan be further transformed into Weber equations. From Weber equations, the homoclinic orbit solutions can be derived,so the solitary wave solutions to linear equations with variable coefficients are obtained.
Singh, Manpreet; Singh Saini, Nareshpal; Ghai, Yashika; Kaur, Nimardeep
2016-07-01
Dusty plasma is a fully or partially ionized gas which contain micron or sub-micron sized dust particles. These dust particles can be positively or negatively charged, depending upon the mechanism of charging . Dusty plasma is often observed in most of the space and astrophysical plasma environments. Presence of these dust particles can modify the dispersion properties of waves in the plasma and can introduce several new wave modes, e.g., dust acoustic (DA) waves, dust-ion acoustic (DIA) waves, dust-acoustic shock waves etc. In this investigation we have studied the small amplitude dust acoustic waves in an unmagnetized plasma comprising of electrons, positively charged ions, negatively charged hot as well as cold dust. Electrons and ions are described by superthermal distribution which is more appropriate for modeling space and astrophysical plasmas. Kadomtsev- Petviashvili (KP) equation has been derived using reductive perturbation technique. Positive as well as negative potential structures are observed, depending upon some critical values of parameters. Amplitude and width of dust acoustic solitary waves are modified by varying these parameters such as superthermality of electrons and ions, direction of propagation of the wave, relative concentration of hot and cold dust particles etc. This study may be helpful in understanding the formation and dynamics of nonlinear structures in various space and astrophysical plasma environments such Saturn's F-rings.
Exact solitary wave solutions of nonlinear wave equations
Institute of Scientific and Technical Information of China (English)
ZHANG; Guixu
2001-01-01
［1］Ablowitz, M.J., Carkson, P.A., Nonlinear Evolution and Inverse Scattering., New York: Cambridge University Press, 1991, 47-350.［2］Miura, M.R., Bcklund Transformation, Berlin: Springer_Verlag, 1978, 4-156.［3］Hirota, R., Exact solution of the Korteweg_de Vries equation for multiple collisions of solitons, Phys.Rev.Lett., 1971, 27: 1192-1194.［4］Wang, M.L., Zhou, Y.B., Li, Z.B., Application of a homogeneous balance method to exact solutions of nonlinear equations in mathematical physics, Phys.Lett.A, 1996, 213: 67-75.［5］Shang, Y.D., Explicit and exact solutions for a class of nonlinear wave equations, Acta Appl.Math.Sinica (in Chinese), 2000, 23(1): 21-30.［6］Li, Z.B., Zhang, S.Q., Exact solitary wave equations for nonlinear wave equations using symbolic computation, Acta Math.Phys.Sinica (in Chinese), 1997, 17(1): 81-89.［7］Wu Wenjun, On zeros of algebraic equations: An application of Ritt principle, Kexue Tongbao (Chinese Science Bulletin), 1986, 31(1): 1-5.［8］Heegard, C., Little, J., Saints, K., Systematic encoding via grbner bases fro a class of algebraic geometric codes, IEEE Trans.Inform.Theory, 1995, IT_41: 1752-1761.［9］Conte, R., Musette, M., Link between solitary waves and projective Riccati equation, J.Phys.A: Math.Gen., 1992, 25: 2609-2612.［10］Wahlquist, H.D., Estabrook, F.B., Prolongation structures and nonlinear evolution equations, J.Math.Phys., 1975, 16: 1-7.［11］Whitham, G.B., Linear and Nonlinear Waves, New York: Wiley, 1974, 44.［12］Constantin, P., Foias, C., Nicolaenko, B., Integral Manifolds and Inertial Manifolds for Dissipative Partial Differtial Equations, New York: Springer_Verlag, 1981, 111-118.［13］Chen, S.R., Chen, X.J., Completeness relation of squared Jost functions to the NLS equation, Acta Phys.Sinica (in Chinese), 1999, 48(5): 882-886.
Solitary Wave and Non-traveling Wave Solutions to Two Nonlinear Evolution Equations
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
By applying the extended homogeneous balance method, we find some new explicit solutions to two nonlinear evolution equations, which include n-resonance plane solitary wave and non-traveling wave solutions.
Solitary-wave propagation and interactions for a sixth-order generalized Boussinesq equation
Directory of Open Access Journals (Sweden)
Bao-Feng Feng
2005-01-01
based on the phase plane analysis around the equilibrium point, is used to construct the solitary-wave solutions for this nonintegrable equation. A symmetric three-level implicit finite difference scheme with a free parameter θ is proposed to study the propagation and interactions of solitary waves. Numerical simulations show the propagation of a single solitary wave of SGBE, and two solitary waves pass by each other without changing their shapes in the head-on collisions.
NUMERICAL STUDY OF SOLITARY WAVE FISSION OVER AN UNDERWATER STEP
Institute of Scientific and Technical Information of China (English)
LU Ji; YU Xi-ping
2008-01-01
Solitary wave fission over an underwater step is numerically investigated. The numerical model is based on the enhanced Boussinesq equations, which appropriately represent both the nonlinearity and dispersivity of surface water waves. The finite difference method defined on the staggered grid in space with an implicit scheme for time stepping is employed for the numerical solution of the governing equations. It is demonstrated that Boussinesq type equations, though they are vertically integrated, can describe the details of the solitary wave fission process with very good accuracy. Numerical results of the reflected and transmitting wave heights, the number of solitons emitted from the transmitting wave and their amplitudes all agree very well with the analytical solution derived from KdV equation by virtue of a linear long wave approximation in the vicinity of the underwater step.
Existence of solitary travelling waves in interfacial electrohydrodynamics
Hammerton, Paul
2013-01-01
The propagation of waves on the surface of a fluid layer of finite depth is considered in the presence of a normal electric field, due to parallel electrodes at arbitrary separation distance. The combined effect of electric field, gravity and surface tension is considered in the long-wavelength small-amplitude limit. Travelling wave solutions are characterised in terms of the Froude number, an electric Weber number and a Bond number and conditions for the existence of solitary waves are deter...
Single-peak solitary wave solutions for the variant Boussinesq equations
Indian Academy of Sciences (India)
Hong Li; Lilin Ma; Dahe Feng
2013-06-01
This paper presents all possible smooth, cusped solitary wave solutions for the variant Boussinesq equations under the inhomogeneous boundary condition. The parametric conditions for the existence of smooth, cusped solitary wave solutions are given using the phase portrait analytical technique. Asymptotic analysis and numerical simulations are provided for smooth, cusped solitary wave solutions of the variant Boussinesq equations.
Experiments and computation of onshore breaking solitary waves
DEFF Research Database (Denmark)
Jensen, A.; Mayer, Stefan; Pedersen, G.K.
2005-01-01
This is a combined experimental and computational study of solitary waves that break on-shore. Velocities and accelerations are measured by a two-camera PIV technique and compared to theoretical values from an Euler model with a VOF method for the free surface. In particular, the dynamics of a so...
Internal solitary waves in the Red Sea: An unfolding mystery
da Silva, J.C.B.; Magalhães, J.M.; Gerkema, T.; Maas, L.R.M.
2012-01-01
The off-shelf region between 16.0 degrees and 16.5 degrees N in the southern Red Sea is identified as a new hotspot for the occurrence of oceanic internal solitary waves. Satellite observations reveal trains of solitons that, surprisingly, appear to propagate from the center of the Red Sea, where it
No solitary waves exist on 2D deep water
Hur, Vera Mikyoung
2015-01-01
The solitary wave problem at the free surface of a two-dimensional, infinitely-deep and irrotational flow of water, under the influence of gravity, is formulated as a nonlinear pseudodifferential equation. A Pohozaev identity is used to show that it admits no solutions which asymptotically vanish faster than linearly.
Nonpropagating Solitary Waves in (2+1)-Dimensional Nonlinear Systems
Institute of Scientific and Technical Information of China (English)
MENG Jian-Ping; ZHANG Jie-Fang
2005-01-01
By means of extended homogeneous balance method and variable separation approach, quite a general variable separation solution of the (2+1)-dimensional Broer-Kaup-Kupershmidt equation is derived. From the variable separation solution and by selecting appropriate functions, a new class of (2+1)-dimensional nonpropagating solitary waves are found. The novel features exhibited by these new structures are first revealed.
Solitary plane waves in an isotropic hexagonal lattice
DEFF Research Database (Denmark)
Zolotaryuk, Yaroslav; Savin, A.V.; Christiansen, Peter Leth
1998-01-01
Solitary plane-wave solutions in a two-dimensional hexagonal lattice which can propagate in different directions on the plane are found by using the pseudospectral method. The main point of our studies is that the lattice model is isotropic and we show that the sound velocity is the same for diff...
Grey Self-similar Solitary Waves in Inhomogeneous Nonlinear Media
Institute of Scientific and Technical Information of China (English)
LI Hua-Mei
2009-01-01
This paper analyzes spatial grey self-similar solitary waves propagation and collision in graded-index nonlinear waveguide amplifiers with self-focusing and self-defocusing Kerr nonlinearities.New exact self-similar solutions are found using a novel transformation and their main features are investigated by using direct computer simulations.
Electron acoustic waves in a magnetized plasma with kappa distributed ions
Energy Technology Data Exchange (ETDEWEB)
Devanandhan, S.; Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Singh, S. V. [Indian Institute of Geomagnetism, Navi Mumbai (India); School of Physics, University of Kwazulu-Natal, Durban (South Africa); Bharuthram, R. [University of the Western Cape, Bellville (South Africa)
2012-08-15
Electron acoustic solitary waves in a two component magnetized plasma consisting of fluid cold electrons and hot superthermal ions are considered. The linear dispersion relation for electron acoustic waves is derived. In the nonlinear regime, the energy integral is obtained by a Sagdeev pseudopotential analysis, which predicts negative solitary potential structures. The effects of superthermality, obliquity, temperature, and Mach number on solitary structures are studied in detail. The results show that the superthermal index {kappa} and electron to ion temperature ratio {sigma} alters the regime where solitary waves can exist. It is found that an increase in magnetic field value results in an enhancement of soliton electric field amplitude and a reduction in soliton width and pulse duration.
Flow and sediment transport induced by a plunging solitary wave
DEFF Research Database (Denmark)
Sumer, B. Mutlu; Sen, M.Berke; Karagali, Ioanna;
2011-01-01
Two parallel experiments involving the evolution and runup of plunging solitary waves on a sloping bed were conducted: (1) a rigid-bed experiment, allowing direct (hot film) measurements of bed shear stresses, and (2) a sediment-bed experiment, allowing for the measurement of pore-water pressures......, and for observation of the morphological changes. The two experimental conditions were maintained as similar as possible. The experiments showed that the complete sequence of the plunging solitary wave involves the following processes: Shoaling and wave breaking; Runup; Rundown and hydraulic jump; and Trailing wave...... affected, by as much as a factor of 2, in the runup and hydraulic jump stages. The pore-water pressure measurements showed that the sediment at (or near) the surface of the bed experiences upward-directed pressure gradient forces during the downrush phase. The magnitude of this force can reach values...
Solitary and periodic waves in two-fluid magnetohydrodynamics
Gavrikov, M. B.; Kudryashov, N. A.; Petrov, B. A.; Savelyev, V. V.; Sinelshchikov, D. I.
2016-09-01
A system of equations of two-fluid magnetohydrodynamics is studied. An ordinary differential equation describing traveling waves in an ideal cold quasi-neutral plasma is obtained in the case of quasi-stationary electromagnetic field. The Painlevé analysis of this equation is carried out and the general solution of the equation is constructed in terms of the Weierstrass elliptic function. Solitary and periodic wave solutions for the components of magnetic field are found and analyzed.
The frustrated Brownian motion of nonlocal solitary waves
Folli, Viola
2010-01-01
We investigate the evolution of solitary waves in a nonlocal medium in the presence of disorder. By using a perturbational approach, we show that an increasing degree of nonlocality may largely hamper the Brownian motion of self-trapped wave-packets. The result is valid for any kind of nonlocality and in the presence of non-paraxial effects. Analytical predictions are compared with numerical simulations based on stochastic partial differential equation
Existence of solitary waves in dipolar quantum gases
Antonelli, Paolo
2011-02-01
We study a nonlinear Schrdinger equation arising in the mean field description of dipolar quantum gases. Under the assumption of sufficiently strong dipolar interactions, the existence of standing waves, and hence solitons, is proved together with some of their properties. This gives a rigorous argument for the possible existence of solitary waves in BoseEinstein condensates, which originate solely due to the dipolar interaction between the particles. © 2010 Elsevier B.V. All rights reserved.
Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials
Shen, Jian Qi
2016-08-01
In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.
Solitary wave shoaling and breaking in a regularized Boussinesq system
Senthilkumar, Amutha
2016-01-01
A coupled BBM system of equations is studied in the situation of water waves propagating over decreasing fluid depth. A conservation equation for mass and a wave breaking criterion valid in the Boussinesq approximation is found. A Fourier collocation method coupled with a 4-stage Runge-Kutta time integration scheme is employed to approximate solutions of the BBM system. The mass conservation equation is used to quantify the role of reflection in the shoaling of solitary waves on a sloping bottom. Shoaling results based on an adiabatic approximation are analyzed. Wave shoaling and the criterion of breaking solitary waves on a sloping bottom is studied. To validate the numerical model the simulation results are compared with those obtained by Grilli et al.[16] and a good agreement between them is observed. Shoaling of solitary waves of two different types of mild slope model systems in [8] and [13] are compared, and it is found that each of these models works well in their respective regimes of applicability.
SOLITARY WAVES IN FINITE DEFORMATION ELASTIC CIRCULAR ROD
Institute of Scientific and Technical Information of China (English)
LIU Zhi-fang; ZHANG Shan-yuan
2006-01-01
A new nonlinear wave equation of a finite deformation elastic circular rod simultaneously introducing transverse inertia and shearing strain was derived by means of Hamilton principle. The nonlinear equation includes two nonlinear terms caused by finite deformation and double geometric dispersion effects caused by transverse inertia and transverse shearing strain. Nonlinear wave equation and corresponding truncated nonlinear wave equation were solved by the hyperbolic secant function finite expansion method. The solitary wave solutions of these nonlinear equations were obtained. The necessary condition of these solutions existence was given also.
Orbital Stability of Solitary Waves of The Long Wave—Short Wave Resonance Equations
Institute of Scientific and Technical Information of China (English)
BolingGUO; LinCHEN
1996-01-01
This paper concerns the orbital stability for soliary waves of the long wave short wave resonance equations.By using a different method from[15] ,applying the abstract rsults of Grillakis et al.[8][9] and detailed spectral analysis.we obtain the necessary and sufficient condition for the stability of the solitary waves.
Semi-analytic variable charge solitary waves involving dust phase-space vortices (holes)
Energy Technology Data Exchange (ETDEWEB)
Tribeche, Mouloud; Younsi, Smain; Amour, Rabia; Aoutou, Kamel [Plasma Physics Group, Faculty of Sciences-Physics, Theoretical Physics Laboratory, University of Bab-Ezzouar, USTHB BP 32, El Alia, Algiers 16111 (Algeria)], E-mail: mtribeche@usthb.dz
2009-09-15
A semi-analytic model for highly nonlinear solitary waves involving dust phase-space vortices (holes) is outlined. The variable dust charge is expressed in terms of the Lambert function and we take advantage of this transcendental function to investigate the localized structures that may occur in a dusty plasma with variable charge trapped dust particles. Our results which complement the previously published work on this problem (Schamel et al 2001 Phys. Plasmas 8 671) should be of basic interest for experiments that involve the trapping of dust particles in ultra-low-frequency dust acoustic modes.
Indian Academy of Sciences (India)
Hong-Yan Wang; Kai-Biao Zhang
2015-01-01
Propagation of small but finite nonlinear dust-acoustic solitary waves are investigated in a planar unmagnetized dusty plasma, which consists of electrons, positrons, ions and negatively charged dust particles with different sizes and masses. A Kadomtsev–Petviashvili (KP) equation is obtained by using reductive perturbation method. The effect of positron density and positron–electron temperature ratio on dust-acoustic solitary structures are studied. Numerical results show that the increase in positron number density increases the amplitude of hump-like solitons but decreases the dip-like solitary waves. Furthermore, increase in the positron–electron temperature ratio results in the decrease of the amplitude of dip-like solitary waves. It seems that both the dipand hump-like solitary waves can exist in this system. Our results also suggest that the dust-size distribution has a significant role on the amplitude of the solitary waves.
A solitary wave of a relativistic magnetosonic wave propagating perpendicularly to a magnetic field
International Nuclear Information System (INIS)
A relativistic theory for a nonlinear magnetosonic wave propagating perpendicularly to a magnetic field is developed. On the basis of a relativistic two-fluid cold plasma model, structure of a stationary magnetosonic wave is studied. Relativistic effects become important for the parameter regime ωce/ωpe > approx 1, because the fluid electron velocity perpendicular to a magnetic field and parallel to the wave front takes values close to the speed of light for such plasma parameters. It is found that there exists a stationary solitary wave solution even in the relativistic model. Some properties of the solitary wave, such as the soliton width, are discussed. (author)
Nonlinear dust-ion-acoustic waves in a multi-ion plasma with trapped electrons
Indian Academy of Sciences (India)
S S Duha; B Shikha; A A Mamun
2011-08-01
A dusty multi-ion plasma system consisting of non-isothermal (trapped) electrons, Maxwellian (isothermal) light positive ions, warm heavy negative ions and extremely massive charge ﬂuctuating stationary dust have been considered. The dust-ion-acoustic solitary and shock waves associated with negative ion dynamics, Maxwellian (isothermal) positive ions, trapped electrons and charge ﬂuctuating stationary dust have been investigated by employing the reductive perturbation method. The basic features of such dust-ion-acoustic solitary and shock waves have been identiﬁed. The implications of our ﬁndings in space and laboratory dusty multi-ion plasmas are discussed.
On the Synchronization of Acoustic Gravity Waves
Lonngren, Karl E.; Bai, Er-Wei
Using the model proposed by Stenflo, we demonstrate that acoustic gravity waves found in one region of space can be synchronized with acoustic gravity waves found in another region of space using techniques from modern control theory.
Colliding solitary waves in quark gluon plasmas
Rafiei, Azam; Javidan, Kurosh
2016-09-01
We study the head-on collision of propagating waves due to perturbations in quark gluon plasmas. We use the Massachusetts Institute of Technology bag model, hydrodynamics equation, and suitable equation of state for describing the time evolution of such localized waves. A nonlinear differential equation is derived for the propagation of small amplitude localized waves using the reductive perturbation method. We show that these waves are unstable and amplitude of the left-moving (right-moving) wave increases (decreases) after the collision, and so they reach the borders of a quark gluon plasma fireball with different amplitudes. Indeed we show that such arrangements are created because of the geometrical symmetries of the medium.
Weakly nonlinear models for internal waves: inverse scattering transform and solitary wave contents
Chen, Shengqian
2016-01-01
The time evolution emanating from ``internal dam-break'' initial conditions is studied for a class of models of stratified Euler fluids in configurations close to two-homogeneous layers separated by a thin diffused interface. Direct numerical simulations and experiments in wave tanks show that such initial conditions eventually give rise to coherent structures that are close to solitary-wave solutions moving ahead of a region of dispersive wave motion and turbulent mixing close to the location of the initial dam step. A priori theoretical predictions of the main features of these solitary waves, such as their amplitudes and speeds, appear to be unavailable, even for simplified models of wave evolution in stratified fluids. With the aim of providing estimates of the existence, amplitude and speed of such solitary waves, an approach based on Inverse Scattering Transform (IST) for completely integrable models is developed here and tested against direct numerical simulations of Euler fluids and some of their mode...
Nonlinear dynamics of DNA - Riccati generalized solitary wave solutions
Energy Technology Data Exchange (ETDEWEB)
Alka, W.; Goyal, Amit [Department of Physics, Panjab University, Chandigarh-160014 (India); Nagaraja Kumar, C., E-mail: cnkumar@pu.ac.i [Department of Physics, Panjab University, Chandigarh-160014 (India)
2011-01-17
We study the nonlinear dynamics of DNA, for longitudinal and transverse motions, in the framework of the microscopic model of Peyrard and Bishop. The coupled nonlinear partial differential equations for dynamics of DNA model, which consists of two long elastic homogeneous strands connected with each other by an elastic membrane, have been solved for solitary wave solution which is further generalized using Riccati parameterized factorization method.
Nonlinear dynamics of DNA - Riccati generalized solitary wave solutions
Alka, W.; Goyal, Amit; Nagaraja Kumar, C.
2011-01-01
We study the nonlinear dynamics of DNA, for longitudinal and transverse motions, in the framework of the microscopic model of Peyrard and Bishop. The coupled nonlinear partial differential equations for dynamics of DNA model, which consists of two long elastic homogeneous strands connected with each other by an elastic membrane, have been solved for solitary wave solution which is further generalized using Riccati parameterized factorization method.
Airy-type solitary wave in highly noninstantaneous Kerr media.
Deng, Fu; Hong, Weiyi; Deng, Dongmei
2016-07-11
We investigate the dynamics of a decelerating Airy pulse in the highly noninstantaneous Kerr media. It is found that the deceleration of the Airy pulse can be counteracted by the highly noninstantaneous nonlinearity. When the power of the pulse is specifically chosen, the deceleration of the Airy pulse can be totally restrained, and an Airy-type solitary wave is observed within several dispersion lengths. PMID:27410868
Dynamics of solitary waves in the Zakharov model equations
International Nuclear Information System (INIS)
We analyze internal vibrations of a solitary wave in the generalized Zakharov system (including a direct nonlinear self-interaction of the high-frequency field) by means of a variational approach. The application of the variational approximation to this model turns out to be nontrivial, as one needs to renormalize the Lagrangian in order to avoid divergences. This is done with the use of two fundamental integrals of motion of the model. We derive a Hamiltonian two-degrees-of-freedom dynamical system that governs internal vibrations of the solitary wave. The eigenfrequencies of the small oscillations around the unperturbed solitary wave are found explicitly, one of them lying inside the gap of the high-frequency subsystem, the other one being well above the gap. Finite-amplitude oscillations are simulated numerically. It is shown that these oscillations remain regular if the perturbation does not break the balance between the two integrals of motion, while in the opposite case the oscillations are more irregular and may possibly become chaotic. copyright 1997 The American Physical Society
Groeskamp, Sjoerd; Nauw, Janine J.; Maas, Leo R. M.
2011-11-01
Despite vigorous tidal and wind mixing, observations in an estuarine tidal inlet in the Wadden Sea show that during part of the tidal cycle, vertical stratification and internal waves may still develop. Acoustic Doppler current profiler (ADCP) and conductivity, temperature, depth observations, collected over the past 6 years at 13 h anchor stations (ASs), reveal that these occur especially during slack tide, when there is little wind and large freshwater discharge from nearby Lake IJssel. Measurements with a moored ADCP show that in the same tidal phase, strong cross-channel circulation develops, which may suddenly reverse circulation sense due to passing density fronts. In the vertically stratified phase that follows after the front passage, propagating mode-one solitary internal waves are observed. These are resonantly generated during decelerating tidal ebb currents when the (shear) flow passes a transcritical regime (Froude number equal to 1). A combination of photographs (including one from the International Space Station), bathymetric data, and ASs data leads to the discovery of yet another source of internal waves in this area, produced during slackening tide by propagating lee waves that develop over a deep trench. We suggest that both the cross-channel circulation as well as the (solitary) internal waves may locally be of importance for the (re)distribution and transport of sediments and nutrients and may influence tidally averaged transports.
Loss of stability of a solitary wave through exciting a cnoidal wave on a Fermi-Pasta-Ulam ring
Yuan, Zongqiang; Chu, Min; Xia, Guodong; Zheng, Zhigang
2013-01-01
The spatiotemporal propagation behavior of a solitary wave is investigated on a Fermi-Pasta-Ulam ring. We observe the emergence of a cnoidal wave excited by the solitary wave. The cnoidal wave may coexist with the solitary wave for a long time associated with the periodic exchange of energy between these two nonlinear waves. The module of the cnoidal wave, which is considered as an indicator of the nonlinearity, is found to oscillate with the same period of the energy exchange. After the stage of coexistence, the interaction between these two nonlinear waves leads to the destruction of the cnoidal wave by the radiation of phonons. Finally, the interaction of the solitary wave with phonons leads to the loss of stability of the solitary wave.
Institute of Scientific and Technical Information of China (English)
CHENYong; YANZhen－Ya; 等
2002-01-01
In this paper,we study the generalized coupled Hirota-Satsuma KdV system by using the new generalized transformation in homogeneous balance method.As a result,many explicit exact solutions,which contain new solitary wave solutions,periodic wave solutions,and the combined formal solitary wave solutions,and periodic wave solutions ,are obtained.
An experimental study on runup of two solitary waves on plane beaches
Institute of Scientific and Technical Information of China (English)
XUAN Rui-tao; WU Wei; LIU Hua
2013-01-01
Experiments of the runup of two solitary waves on a plane beach are carried out in a wave flume.The two solitary waves with the same amplitude and the crest separating distances are generated by using an improved wave generation method.It is found that,with regard to the two solitary waves with same wave amplitude,the runup amplification of the second wave is less than that of the first wave if the relative crest separating distance is reduced to a certain threshold value.The rundown of the first solitary wave depresses the maximum runup of the second wave.If the leading solitary wave is of relatively smaller amplitude for the two solitary waves,the runup amplification is affected by the overtaking process of two solitary waves.It turns out that the runup amplification of the second wave is larger than that of the first wave if the similarity factor is approximately larger than 15,which means the larger wave overtakes the smaller one before the waves runup on a beach.
Small amplitude solitary waves in the Dirac-Maxwell system
Comech, Andrew; Stuart, David
2012-01-01
We study nonlinear bound states, or solitary waves, in the Dirac-Maxwell system proving the existence of solutions in which the Dirac wave function is of the form $\\phi(x,\\omega)e^{-i\\omega t}$, $\\omega\\in(-m,\\omega_*)$, with some $\\omega_*>-m$, such that $\\phi_\\omega\\in H^1(\\R^3,\\C^4)$, $\\Vert\\phi_\\omega\\Vert^2_{L^2}=O(m-|\\omega|)$, and $\\Vert\\phi_\\omega\\Vert_{L^\\infty}=O(m-|\\omega|)$. The method of proof is an implicit function theorem argument based on an identification of the nonrelativis...
The Froude number for solitary water waves with vorticity
Wheeler, Miles H.
2014-01-01
We consider two-dimensional solitary water waves on a shear flow with an arbitrary distribution of vorticity. Assuming that the horizontal velocity in the fluid never exceeds the wave speed and that the free surface lies everywhere above its asymptotic level, we give a very simple proof that a suitably defined Froude number $F$ must be strictly greater than the critical value $F=1$. We also prove a related upper bound on $F$, and hence on the amplitude, under more restrictive assumptions on t...
Rotating solitary wave at the wall of a cylindrical container
Amaouche, Mustapha
2013-04-30
This paper deals with the theoretical modeling of a rotating solitary surface wave that was observed during water drainage from a cylindrical reservoir, when shallow water conditions were reached. It represents an improvement of our previous study, where the radial flow perturbation was neglected. This assumption led to the classical planar Korteweg–de Vries equation for the wall wave profile, which did not account for the rotational character of the base flow. The present formulation is based on a less restricting condition and consequently corrects the last shortcoming. Now the influence of the background flow appears in the wave characteristics. The theory provides a better physical depiction of the unique experiment by predicting fairly well the wave profile at least in the first half of its lifetime and estimating the speed of the observed wave with good accuracy.
Study of nonlinear ion- and electron-acoustic waves in multi-component space plasmas
Directory of Open Access Journals (Sweden)
G. S. Lakhina
2008-11-01
Full Text Available Large amplitude ion-acoustic and electron-acoustic waves in an unmagnetized multi-component plasma system consisting of cold background electrons and ions, a hot electron beam and a hot ion beam are studied using Sagdeev pseudo-potential technique. Three types of solitary waves, namely, slow ion-acoustic, ion-acoustic and electron-acoustic solitons are found provided the Mach numbers exceed the critical values. The slow ion-acoustic solitons have the smallest critical Mach numbers, whereas the electron-acoustic solitons have the largest critical Mach numbers. For the plasma parameters considered here, both type of ion-acoustic solitons have positive potential whereas the electron-acoustic solitons can have either positive or negative potential depending on the fractional number density of the cold electrons relative to that of the ions (or total electrons number density. For a fixed Mach number, increases in the beam speeds of either hot electrons or hot ions can lead to reduction in the amplitudes of the ion-and electron-acoustic solitons. However, the presence of hot electron and hot ion beams have no effect on the amplitudes of slow ion-acoustic modes. Possible application of this model to the electrostatic solitary waves (ESWs observed in the plasma sheet boundary layer is discussed.
Eady Solitary Waves: A Theory of Type B Cyclogenesis.
Mitsudera, Humio
1994-11-01
Localized baroclinic instability in a weakly nonlinear, long-wave limit using an Eady model is studied. The resulting evolution equations have a form of the KdV type, including extra terms representing linear coupling. Baroclinic instability is triggered locally by the collision between two neutral solitary waves (one trapped at the upper boundary and the other at the lower boundary) if their incident amplitudes are sufficiently large. This characteristic is explained from the viewpoint of resonance when the relative phase speed, which depends on the amplitudes, is less than a critical value. The upper and lower disturbances grow in a coupled manner (resembling a normal-mode structure) initially, but they reverse direction slowly as the amplitudes increase, and eventually separate from each other.The motivation of this study is to investigate a type of extratropical cyclogenesis that involves a preexisting upper trough (termed as Type B development) from the viewpoint of resonant solitary waves. Two cases are of particular interest. First, the author examines a case where an upper disturbance preexists over an undisturbed low-level waveguide. The solitary waves exhibit behavior similar to that conceived by Hoskins et al. for Type B development; the lower disturbance is forced one sidedly by a preexisting upper disturbance initially, but in turn forces the latter once the former attains a sufficient amplitude, thus resulting in mutual reinforcement. Second, if a weak perturbation exists at the surface ahead of the preexisting strong upper disturbance, baroclinic instability is triggered when the two waves interact. Even though the amplitude of the lower disturbance is initially much weaker, it is intensified quickly and catches up with the amplitude of the upper disturbance, so that the coupled vertical structure resembles that of an unstable normal mode eventually. These results describe the observed behavior in Type B atmospheric cyclogenesis quite well.
A double optical solitary wave in a nonlinear Schr(o)dinger-type equation
Institute of Scientific and Technical Information of China (English)
Yin Jiu-Li; Ding Shan-Yu
2013-01-01
A qualitative analysis method to efficiently solve the shallow wave equations is improved,so that a more complicated nonlinear Schr(o)dinger equation can be considered.By using the detailed study,some quite strange optical solitary waves are obtained in which the bright and dark optical solitary waves are allowed to coexist.
Stability and Decay properties of Solitary wave solutions for the generalized BO-ZK equation
Esfahani, Amin
2009-01-01
In this paper we study the generalized BO-ZK equation in two dimensions. We classify the existence and non-existence of solitary waves depending on the sign of the dispersions and on the nonlinearity. By using the approach introduced by Cazenave and Lions we study the nonlinear stability of solitary waves. We also prove some decay and regularity properties of such waves.
Laboratory Generation of Solitary Waves:An Inversion Technique to Improve Available Methods
Institute of Scientific and Technical Information of China (English)
A.Romano; M.Guerrini; G.Bellotti; 琚烈红
2014-01-01
Solitary waves are often used in laboratory experiments to study tsunamis propagation and interaction with coasts. However, the experimental shape of the waves may differ from the theoretical one. In this paper, a correction technique aiming at minimizing the discrepancies between the two profiles is presented. Laboratory experiments reveal their effectiveness in correcting the experimental shape of solitary waves, mainly for low nonlinearities.
Transition from Solitons to Solitary Waves in the Fermi-Pasta-Ulam Lattice
Wen, Zhenying; Wei, Nian
2016-01-01
In this paper, we study the smooth transition from solitons to solitary waves in localization, relation between energy and velocity, propagation and scattering property in the Fermi-Pasta-Ulam lattice analytically and numerically. A soliton is a very stable solitary wave that retains its permanent structure after interacting with other solitary waves. A soliton exists when the energy is small, and it becomes a solitary wave when the energy increases to the threshold. The transition could help to understand the distinctly different heat conduction behaviors of the Fermi-Pasta-Ulam lattice at low and high temperature.
A new model for algebraic Rossby solitary waves in rotation fluid and its solution
Chen, Yao-Deng; Yang, Hong-Wei; Gao, Yu-Fang; Yin, Bao-Shu; Feng, Xing-Ru
2015-09-01
A generalized Boussinesq equation that includes the dissipation effect is derived to describe a kind of algebraic Rossby solitary waves in a rotating fluid by employing perturbation expansions and stretching transformations of time and space. Using this equation, the conservation laws of algebraic Rossby solitary waves are discussed. It is found that the mass, the momentum, the energy, and the velocity of center of gravity of the algebraic solitary waves are conserved in the propagation process. Finally, the analytical solution of the equation is generated. Based on the analytical solution, the properties of the algebraic solitary waves and the dissipation effect are discussed. The results point out that, similar to classic solitary waves, the dissipation can cause the amplitude and the speed of solitary waves to decrease; however, unlike classic solitary waves, the algebraic solitary waves can split during propagation and the decrease of the detuning parameter can accelerate the occurrence of the solitary waves fission phenomenon. Project supported by the Shandong Provincial Key Laboratory of Marine Ecology and Environment and Disaster Prevention and Mitigation Project, China (Grant No. 2012010), the National Natural Science Foundation of China (Grant Nos. 41205082 and 41476019), the Special Funds for Theoretical Physics of the National Natural Science Foundation of China (Grant No. 11447205), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), China.
Energy Technology Data Exchange (ETDEWEB)
Hossen, M. R.; Nahar, L.; Mamun, A. A. [Jahangirnagar University,Savar, Dhaka (Bangladesh)
2014-12-15
The properties of time-dependent cylindrical and spherical, modified ion-acoustic (mIA) solitary structures in relativistic degenerate multi-ion plasmas (containing degenerate electron fluids, inertial positively-, as well as negatively-, charged light ions, and positively-charged static heavy ions) have been investigated theoretically. This investigation is valid for both non-relativistic and ultrarelativistic limits. The well-known reductive perturbation method has been used to derive the Korteweg-de Vries (K-dV) and the mK-dV equations for studying the basic features of solitary waves. The fundamental characteristics of mIA solitary waves are found to be significantly modified by the effects of the degenerate pressures of the electron and the ion fluids, their number densities, and the various charge states of heavy ions. The relevance of our results in astrophysical compact objects like white dwarfs and neutron stars, which are of scientific interest, is briefly discussed.
Polarized seismic and solitary waves run-up at the sea bed
Energy Technology Data Exchange (ETDEWEB)
Dennis, L. C.C.; Zainal, A. A.; Faisal, S. Y. [Universiti Teknologi PETRONAS, 31750 Tronoh, Perak (Malaysia); Universiti Teknologi Malaysia, 81310 Johor Bahru (Malaysia)
2012-09-26
The polarization effects in hydrodynamics are studied. Hydrodynamic equation for the nonlinear wave is used along with the polarized solitary waves and seismic waves act as initial waves. The model is then solved by Fourier spectral and Runge-Kutta 4 methods, and the surface plot is drawn. The output demonstrates the inundation behaviors. Consequently, the polarized seismic waves along with the polarized solitary waves tend to generate dissimilar inundation which is more disastrous.
The light filament as vector solitary wave
Kovachev, Lubomir M
2015-01-01
We present an analytical approach to the theory of nonlinear propagation of femtosecond optical pulses with broad-band spectrum in gases. The vector character of the nonlinear third-order polarization is investigated in details, taking into account the carrier to envelope phase. The corresponding system of vector amplitude equations is written by using left-hand and right-hand circular components of the electrical field. We found that this system nonlinear equations admits $3D+1$ vector soliton solution with Lorentz shape. The solution presents relatively stable propagation and rotation with GHz frequency of the vector of the electrical field in plane, orthogonal to the direction of propagation. The evolution of the intensity profile demonstrate weak self-compression and week spherical wave in the first milliseconds of propagation.
Modulational Instability of Dust Ion Acoustic Waves in a Collisional Dusty Plasma
Institute of Scientific and Technical Information of China (English)
XUE Ju-Kui
2003-01-01
The modulational instability of dust ion acoustic waves in a dust plasma with ion-dust collision effects is studied. Using the perturbation method, a modified nonlinear Schrodinger equation contains a damping term that comes from the effect of the ion-dust collision is derived. It is found that the inclusion of the ion-dust collision would modify the modulational instability of the wave packet and could not admit any stationary envelope solitary waves.
Internal solitary waves in the Red Sea: An unfolding mystery
Da Silva, J. C. B.; Magalhães, J.M.; T. Gerkema; Maas, L.R.M.
2012-01-01
The off-shelf region between 16.0 degrees and 16.5 degrees N in the southern Red Sea is identified as a new hotspot for the occurrence of oceanic internal solitary waves. Satellite observations reveal trains of solitons that, surprisingly, appear to propagate from the center of the Red Sea, where it is deepest, toward the continental shelf, but they do not survive as coherent structures over the shelf. These solitons are characterized by coherent crest lengths exceeding 80 km and crest-to-cre...
Nonlinear ion-acoustic waves in a degenerate plasma with nuclei of heavy elements
Energy Technology Data Exchange (ETDEWEB)
Hossen, M. A., E-mail: armanplasma@gmail.com; Mamun, A. A., E-mail: mamun-phys@yahoo.co.uk [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh)
2015-10-15
The ion-acoustic (IA) solitary waves propagating in a fully relativistic degenerate dense plasma (containing relativistic degenerate electron and ion fluids, and immobile nuclei of heavy elements) have been theoretically investigated. The relativistic hydrodynamic model is used to derive the Korteweg-de Vries (K-dV) equation by the reductive perturbation method. The stationary solitary wave solution of this K-dV equation is obtained to characterize the basic features of the IA solitary structures that are found to exist in such a degenerate plasma. It is found that the effects of electron dynamics, relativistic degeneracy of the plasma fluids, stationary nuclei of heavy elements, etc., significantly modify the basic properties of the IA solitary structures. The implications of this results in astrophysical compact objects like white dwarfs are briefly discussed.
A unified intrinsic functional expansion theory for solitary waves
Institute of Scientific and Technical Information of China (English)
Theodore Yaotsu Wu; John Kao; Jin E. Zhang
2005-01-01
A new theory is developed here for evaluating solitary waves on water, with results of high accuracy uniformly valid for waves of all heights, from the highest wave with a corner crest of 120° down to very low ones of diminishing height. Solutions are sought for the Euler model by employing a unified expansion of the logarithmic hodograph in terms of a set of intrinsic component functions analytically determined to represent all the intrinsic properties of the wave entity from the wave crest to its outskirts. The unknown coefficients in the expansion are determined by minimization of the mean-square error of the solution, with the minimization optimized so as to take as few terms as needed to attain results as high in accuracy as attainable. In this regard, Stokes's formula, F2μπ = tanμπ, relating the wave speed (the Froude number F) and the logarithmic decrement μ of its wave field in the outskirt, is generalized to establish a new criterion requiring (for minimizing solution error) the functional expansion to contain a finite power series in M terms of Stokes's basic term (singular inμ), such that 2Mμ is just somewhat beyond unity, i.e. 2Mμ (~-) 1. This fundamental criterion is fully validated by solutions for waves Dedicated to Zhemin Zheng for celebration of his Eightieth Anniversary It gives us a great pleasure to dedicate this study to Prof. Zhemin Zheng and join our distinguished colleagues and friends for the jubilant celebration of his Eightieth Anniversary. Warmest tribute is due from us, as from many others unlimited by borders and boundaries, for his contributions of great significance to science, engineering science and engineering, his tremendous influence as a source of inspiration and unerring guide to countless workers in the field, his admirable leadership in fostering the Institute of Mechanics of world renown, as well as for his untiring endeavor in promoting international interaction and cooperation between academies of various nations
Institute of Scientific and Technical Information of China (English)
Xu Chang-Zhi; He Bao-Gang; Zhang Jie-Fang
2004-01-01
A variable separation approach is proposed and extended to the (1+1)-dimensional physical system. The variable separation solutions of (1+1)-dimensional equations of long-wave-short-wave resonant interaction are obtained. Some special type of solutions such as soliton solution, non-propagating solitary wave solution, propagating solitary wave solution, oscillating solitary wave solution are found by selecting the arbitrary function appropriately.
Fukaya, Noriyoshi
2016-01-01
We study the orbital instability of solitary waves for a generalized derivative nonlinear Schr\\"odinger equation. We give sufficient conditions for instability of a two-parameter family of solitary waves in a degenerate case.
Variable separation solutions and new solitary wave structures to the (1+1)-dimensional Ito system
Institute of Scientific and Technical Information of China (English)
Xu Chang-Zhi; He Bao-Gang; Zhang Jie-Fang
2006-01-01
A variable separation approach is proposed and extended to the (1+1)-dimensional physics system.The variable separation solution of (1+1)-dimensional Ito system is obtained.Some special types of solutions such as non-propagating solitary wave solution,propagating solitary wave solution and looped soliton solution are found by selecting the arbitrary function appropriately.
Homotopic mapping solitary traveling wave solutions for the disturbed BKK mechanism physical model
International Nuclear Information System (INIS)
Using the trial equation method, a Broer—Kau—Kupershmidt (BKK) mechanism physical model is obtained, and the exact and approximate solitary traveling wave solutions are found. As an example, it is pointed out that the solitary traveling wave approximate solutions have better accurate degree by using the homotopic mapping theory. (general)
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Using direct algebraic method,exact solitary wave solutions are performed for a class of third order nonlinear dispersive disipative partial differential equations. These solutions are obtained under certain conditions for the relationship between the coefficients of the equation. The exact solitary waves of this class are rational functions of real exponentials of kink-type solutions.
Internal solitary waves in the East China Sea
Institute of Scientific and Technical Information of China (English)
LI Xiaofeng; ZHAO Zhongxiang; HAN Zhen; XU Liuxiong
2008-01-01
A European Space Agency's ENVISAT advanced synthetic aperture radar (ASAR) image covering Zhejiang coastal water in the East China Sea (ECS) was acquired on 1 August 2007. This image shows that there are about 20 coherent internal solitary wave (ISW) packets propagating southwestward toward Zhejiang coast. These ISW packets are separated by about 10 kin, suggesting that these ISWs are tide-generated waves. Each ISW packet contains 5--15 wave crests. The wavelengths of the wave crests with-in the ISW packets are about 300 m. The lengths of the leading wave crests are about 50 km. The ISW amplitude is estimated from solving KdV equation in an ideal two-layer ocean model. It is found that the ISW amplitudes is about 8 m. Further analysis of the ASAR image and ocean stratification profiles show that the observed ISWs are depression waves. Analyzing the tidal current finds that these waves are locally generated. The wavelength and amplitude of the ECS ISW are much smaller than their counter-parts in the South China Sea (SCS). The propagation speed of the ECS ISW is also an order of magnitude smaller than that of the SCS ISW. The observed ISWs in the ECS happened during a spring tide period.
Propagation behavior of acoustic wave in wood
Institute of Scientific and Technical Information of China (English)
Huadong Xu; Guoqi Xu; Lihai Wang; Lei Yu
2014-01-01
We used acoustic tests on a quarter-sawn poplar timbers to study the effects of wood anisotropy and cavity defects on acoustic wave velocity and travel path, and we investigated acoustic wave propagation behavior in wood. The timber specimens were first tested in unmodified condition and then tested after introduction of cavity defects of varying sizes to quantify the transmitting time of acoustic waves in laboratory conditions. Two-dimensional acoustic wave contour maps on the radial section of specimens were then simulated and analyzed based on the experimental data. We tested the relationship between wood grain and acoustic wave velocity as waves passed in various directions through wood. Wood anisotropy has significant effects on both velocity and travel path of acoustic waves, and the velocity of waves passing longitudinally through timbers exceeded the radial velocity. Moreover, cavity defects altered acoustic wave time contours on radial sections of timbers. Acous-tic wave transits from an excitation point to the region behind a cavity in defective wood more slowly than in intact wood.
Numerical simulations of shoaling internal solitary waves of elevation
Xu, Chengzhu; Subich, Christopher; Stastna, Marek
2016-07-01
We present high-resolution, two- and three-dimensional direct numerical simulations of large amplitude internal solitary waves of elevation on the laboratory scale, shoaling onto and over a small-amplitude shelf. The three-dimensional, mapped coordinate, spectral collocation method used for the simulations allows for accurate modelling of both the shoaling waves and the bottom boundary layer. The shoaling of the waves is characterized by the formation of a quasi-trapped core which undergoes a spatially growing stratified shear instability at its edge and a lobe-cleft instability in its nose. Both of these instabilities develop and three-dimensionalize concurrently, leading to strong bottom shear stress. We explore significant regions of Schmidt and Reynolds number space and demonstrate that the formation of shear instabilities during shoaling is robust and should be readily observable in a number of standard laboratory setups. In the experiments with a corrugated bottom boundary, boundary layer separation is found inside each of the corrugations during shoaling. This more complex boundary layer phenomenology precludes the formation of the lobe-cleft instability almost completely and hence provides a different mechanism for fluid and material exchange across the bottom boundary layer. Our analyses suggest that all of these wave-induced instabilities can lead to enhanced turbulence in the water column and increased shear stress on the bottom boundary. Through the generation and evolution of these instabilities, the shoaling of internal solitary waves of elevation is likely to provide systematic mechanisms for material mixing, cross-boundary layer transport, and sediment resuspension.
Bifurcation and Solitary Waves of the Combined KdV and KdV Equation
Institute of Scientific and Technical Information of China (English)
HUA Cun-Cai; LIU Yan-Zhu
2002-01-01
Bifurcation, bistability and solitary waves of the combined KdV and mKdV equation are investigatedsystematically. At first, bifurcation and bistability are analyzed by selecting an integral constant as the bifurcationparameter. Then, different conditions expressed in terms of the bifurcation parameter are obtained for the existence ofbreather-like, algebraic, pulse-like solitary waves, and shock waves. All types of the solitary wave and shock wave solutionsare given by direct integration. Finally, an approximate analytic method by employing the interpolation polynomials iscomplete and the theoretical methods are the simplest hitherto.
Oceanic pycnocline depth retrieval from SAR imagery in the existence of solitary internal waves
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to retrieve the depth indirectly in virtue of the solitary internal waves. A numerical model is presented for retrieving the pycnocline depth from synthetic aperture radar (SAR) images where the solitary internal waves are visible and when ocean waters are fully stratified. This numerical model is constructed by combining the solitary internal wave model and a two-layer ocean model. It is also assumed that the observed groups of solitary internal wave packets on the SAR imagery are generated by local semidiurnal tides. A case study in the East China Sea shows a good agreement with in situ CTD (conductivity-temperature-depth) data.
Ion Acoustic Waves in the Presence of Electron Plasma Waves
DEFF Research Database (Denmark)
Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens
1977-01-01
Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.......Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave....
Solitary-like waves in a liquid foam microchannel
Bouret, Yann; Cohen, Alexandre; Fraysse, Nathalie; Argentina, Médéric; Raufaste, Christophe
2016-08-01
Plateau borders (PBs) are liquid microchannels located at the contact between three bubbles in liquid foams. They are stable, deformable, and can be thought of as quasi-one-dimensional model systems to study surface waves in fluid dynamics. We show that the burst of a bubble trapped in a PB produces local constrictions which travel along the liquid channel at constant velocity, without significant change in shape. These patterns are reminiscent of the depression solitary waves encountered in nonlinear systems. By coupling flow inertia to capillary stresses, we derive a simple model that admits solitonic solutions, which we characterized numerically and analytically in the limit of small deformation. These solutions capture most of the features observed experimentally.
Haider, M. M.; Rahman, O.
2016-07-01
An attempt has been made to study the multi-dimensional instability of dust-ion-acoustic (DIA) solitary waves (SWs) in magnetized multi-ion plasmas containing opposite polarity ions, opposite polarity dusts and non-thermal electrons. First of all, we have derived Zakharov-Kuznetsov (ZK) equation to study the DIA SWs in this case using reductive perturbation method as well as its solution. Small-k perturbation technique was employed to find out the instability criterion and growth rate of such a wave which can give a guideline in understanding the space and laboratory plasmas, situated in the D-region of the Earth's ionosphere, mesosphere, and solar photosphere, as well as the microelectronics plasma processing reactors.
Self-similarity of solitary waves on inertia-dominated falling liquid films.
Denner, Fabian; Pradas, Marc; Charogiannis, Alexandros; Markides, Christos N; van Wachem, Berend G M; Kalliadasis, Serafim
2016-03-01
We propose consistent scaling of solitary waves on inertia-dominated falling liquid films, which accurately accounts for the driving physical mechanisms and leads to a self-similar characterization of solitary waves. Direct numerical simulations of the entire two-phase system are conducted using a state-of-the-art finite volume framework for interfacial flows in an open domain that was previously validated against experimental film-flow data with excellent agreement. We present a detailed analysis of the wave shape and the dispersion of solitary waves on 34 different water films with Reynolds numbers Re=20-120 and surface tension coefficients σ=0.0512-0.072 N m(-1) on substrates with inclination angles β=19°-90°. Following a detailed analysis of these cases we formulate a consistent characterization of the shape and dispersion of solitary waves, based on a newly proposed scaling derived from the Nusselt flat film solution, that unveils a self-similarity as well as the driving mechanism of solitary waves on gravity-driven liquid films. Our results demonstrate that the shape of solitary waves, i.e., height and asymmetry of the wave, is predominantly influenced by the balance of inertia and surface tension. Furthermore, we find that the dispersion of solitary waves on the inertia-dominated falling liquid films considered in this study is governed by nonlinear effects and only driven by inertia, with surface tension and gravity having a negligible influence. PMID:27078461
Identification and determination of solitary wave structures in nonlinear wave propagation
Energy Technology Data Exchange (ETDEWEB)
Newman, W.I.; Campbell, D.K.; Hyman, J.M.
1991-01-01
Nonlinear wave phenomena are characterized by the appearance of solitary wave coherent structures'' traveling at speeds determined by their amplitudes and morphologies. Assuming that these structures are briefly noninteracting, we propose a method for the identification of the number of independent features and their respective speeds. Using data generated from an exact two-soliton solution to the Korteweg-de-Vries equation, we test the method and discuss its strengths and limitations. 41 refs., 2 figs.
On Collisionless Damping of Ion Acoustic Waves
DEFF Research Database (Denmark)
Jensen, Vagn Orla; Petersen, P.I.
1973-01-01
Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero.......Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero....
Features of fluid flows in strongly nonlinear internal solitary waves
Directory of Open Access Journals (Sweden)
S. Semin
2014-12-01
Full Text Available The characteristics of highly nonlinear solitary internal waves (solitons are calculated within the fully nonlinear numerical model of the Massachusetts Institute of Technology. The verification and adaptation of the model is based on the data from laboratory experiments. The present paper also compares the results of our calculations with the calculations performed in the framework of the fully nonlinear Bergen Ocean Model. The comparison of the computed soliton parameters with the predictions of the weakly nonlinear theory based on the Gardner equation is given. The occurrence of reverse flow in the bottom layer directly behind the soliton is confirmed in the numerical simulations. The trajectories of Lagrangian particles in the internal soliton on the surface, on the pycnocline and near the bottom are computed.
Selim, M. M.; El-Depsy, A.; El-Shamy, E. F.
2015-12-01
Properties of nonlinear ion-acoustic travelling waves propagating in a three-dimensional multicomponent magnetoplasma system composed of positive ions, negative ions and superthermal electrons are considered. Using the reductive perturbation technique (RPT), the Zkharov-Kuznetsov (ZK) equation is derived. The bifurcation theory of planar dynamical systems is applied to investigate the existence of the solitary wave solutions and the periodic travelling wave solutions of the resulting ZK equation. It is found that both compressive and rarefactive nonlinear ion-acoustic travelling waves strongly depend on the external magnetic field, the unperturbed positive-to-negative ions density ratio, the direction cosine of the wave propagation vector with the Cartesian coordinates, as well as the superthermal electron parameter. The present model may be useful for describing the formation of nonlinear ion-acoustic travelling wave in certain astrophysical scenarios, such as the D and F-regions of the Earth's ionosphere.
Run-up of non-breaking double solitary waves with equal wave heights on a plane beach
Institute of Scientific and Technical Information of China (English)
王本龙; 董杰; 刘桦
2014-01-01
The evolution and run-up of double solitary waves on a plane beach were studied numerically using the nonlinear shallow water equations (NSWEs) and the Godunov scheme. The numerical model was validated through comparing the present numerical results with analytical solutions and laboratory measurements available for propagation and run-up of single solitary wave. Two successive solitary waves with equal wave heights and variable separation distance of two crests were used as the incoming wave on the open boundary at the toe of a slope beach. The run-ups of the first wave and the second wave with different separation distances were investigated. It is found that the run-up of the first wave does not change with the separation distance and the run-up of the second wave is affected slightly by the separation distance when the separation distance is gradually shortening. The ratio of the maximum run-up of the second wave to one of the first wave is related to the separation distance as well as wave height and slope. The run-ups of double solitary waves were compared with the linearly superposed results of two individual solitary-wave run-ups. The comparison reveals that linear superposition gives reasonable prediction when the separation distance is large, but it may overestimate the actual run-up when two waves are close.
Eulerian Simulation of Acoustic Waves Over Long Range in Realistic Environments
Chitta, Subhashini; Steinhoff, John
2015-11-01
In this paper, we describe a new method for computation of long-range acoustics. The approach is a hybrid of near and far-field methods, and is unique in its Eulerian treatment of the far-field propagation. The near-field generated by any existing method to project an acoustic solution onto a spherical surface that surrounds a source. The acoustic field on this source surface is then extended to an arbitrarily large distance in an inhomogeneous far-field. This would normally require an Eulerian solution of the wave equation. However, conventional Eulerian methods have prohibitive grid requirements. This problem is overcome by using a new method, ``Wave Confinement'' (WC) that propagates wave-identifying phase fronts as nonlinear solitary waves that live on grid indefinitely. This involves modification of wave equation by the addition of a nonlinear term without changing the basic conservation properties of the equation. These solitary waves can then be used to ``carry'' the essential integrals of the acoustic wave. For example, arrival time, centroid position and other properties that are invariant as the wave passes a grid point. Because of this property the grid can be made as coarse as necessary, consistent with overall accuracy to resolve atmospheric/ground variations. This work is being funded by the U.S. Army under a Small Business Innovation Research (SBIR) program (contract number: # W911W6-12-C-0036). The authors would like to thank Dr. Frank Caradonna and Dr. Ben W. Sim for this support.
FISSION LAWS OF INITIALLY INTERFACE SOLITARY WAVES IN TWO-LAYER OCEAN
Institute of Scientific and Technical Information of China (English)
XU Zhao-ting; SHEN Guo-jin; QIAO Fang-li
2004-01-01
A 2-D KdV equation of two-layer stratified ocean with 2-D topography is recapitulated in the present paper.Based on a reduced version of this 2-D KdV equation,the fission laws of the initially internal solitary waves are studied by means of numerical calculation.From the numerical results,it is shown that the initially interface solitary waves can fission on the continental slope like the initially surface solitary waves and the fission process is a significant generating mechanism of internal interface soliton packet on the continental shelf.
Investigation of co-travelling solitary wave collisions in a granular chain
Anzel, Paul; Daraio, Chiara
2012-04-01
We present investigations into the collision of co-travelling solitary waves in a granular chain. Impulses are injected into the system by means of a piezo stack and the results are compared to a numerical model of discrete masses connected by non-linear springs. Similar to other solitary wave-carrying systems, a phase shift in both interacting solitary waves is observed due to their collision. Additionally, the formation of small secondary waves is observed in both numerical and experimental results. Insight into solitary wave interactions will be important for high-frequency excitation of a granular crystal, which may allow for improved Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) methods.
Coupling between whistler waves and slow-mode solitary waves
Tenerani, Anna; Pegoraro, Francesco; Contel, Olivier Le
2012-01-01
The interplay between electron-scale and ion-scale phenomena is of general interest for both laboratory and space plasma physics. In this paper we investigate the linear coupling between whistler waves and slow magnetosonic solitons through two-fluid numerical simulations. Whistler waves can be trapped in the presence of inhomogeneous external fields such as a density hump or hole where they can propagate for times much longer than their characteristic time scale, as shown by laboratory experiments and space measurements. Space measurements have detected whistler waves also in correspondence to magnetic holes, i.e., to density humps with magnetic field minima extending on ion-scales. This raises the interesting question of how ion-scale structures can couple to whistler waves. Slow magnetosonic solitons share some of the main features of a magnetic hole. Using the ducting properties of an inhomogeneous plasma as a guide, we present a numerical study of whistler waves that are trapped and transported inside pr...
Swimming using surface acoustic waves.
Directory of Open Access Journals (Sweden)
Yannyk Bourquin
Full Text Available Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel.
Swimming using surface acoustic waves.
Bourquin, Yannyk; Cooper, Jonathan M
2013-01-01
Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel. PMID:23431358
Unidirectional propagation of designer surface acoustic waves
Lu, Jiuyang; Ke, Manzhu; Liu, Zhengyou
2014-01-01
We propose an efficient design route to generate unidirectional propagation of the designer surface acoustic waves. The whole system consists of a periodically corrugated rigid plate combining with a pair of asymmetric narrow slits. The directionality of the structure-induced surface waves stems from the destructive interference between the evanescent waves emitted from the double slits. The theoretical prediction is validated well by simulations and experiments. Promising applications can be anticipated, such as in designing compact acoustic circuits.
Response of internal solitary waves to tropical storm Washi in the northwestern South China Sea
Directory of Open Access Journals (Sweden)
Z. H. Xu
2011-11-01
Full Text Available Based on in-situ time series data from an array of temperature sensors and an acoustic Doppler current profiler on the continental shelf of the northwestern South China Sea, a sequence of internal solitary waves (ISWs were observed during the passage of tropical storm Washi in the summer of 2005, which provided a unique opportunity to investigate the ISW response to the tropical cyclone. The passing tropical storm is found to play an important role in affecting the stratification structure of the water column, and consequently leading to significant variability in the propagating features of the ISWs, such as the polarity reversal and amplitude variations of the waves. The response of the ISWs to Washi can be divided into two stages, direct forcing by the strong wind (during the arrival of Washi and remote forcing via the near-inertial internal waves induced by the tropical storm (after the passage of Washi. The field observations as well as a theoretical analysis suggest that the variations of the ISWs closely coincide with the changing stratification structure and shear currents in accompanied by the typhoon wind and near-inertial waves. This study presents the first observations and analysis of the ISW response to the tropical cyclone in the South China Sea.
A Schamel equation for ion acoustic waves in superthermal plasmas
Energy Technology Data Exchange (ETDEWEB)
Williams, G., E-mail: gwilliams06@qub.ac.uk; Kourakis, I. [Centre for Plasma Physics, Department of Physics and Astronomy, Queen' s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Verheest, F. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Hellberg, M. A. [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Anowar, M. G. M. [Department of Physics, Begum Rokeya University, Rangpur, Rangpur-5400 (Bangladesh)
2014-09-15
An investigation of the propagation of ion acoustic waves in nonthermal plasmas in the presence of trapped electrons has been undertaken. This has been motivated by space and laboratory plasma observations of plasmas containing energetic particles, resulting in long-tailed distributions, in combination with trapped particles, whereby some of the plasma particles are confined to a finite region of phase space. An unmagnetized collisionless electron-ion plasma is considered, featuring a non-Maxwellian-trapped electron distribution, which is modelled by a kappa distribution function combined with a Schamel distribution. The effect of particle trapping has been considered, resulting in an expression for the electron density. Reductive perturbation theory has been used to construct a KdV-like Schamel equation, and examine its behaviour. The relevant configurational parameters in our study include the superthermality index κ and the characteristic trapping parameter β. A pulse-shaped family of solutions is proposed, also depending on the weak soliton speed increment u{sub 0}. The main modification due to an increase in particle trapping is an increase in the amplitude of solitary waves, yet leaving their spatial width practically unaffected. With enhanced superthermality, there is a decrease in both amplitude and width of solitary waves, for any given values of the trapping parameter and of the incremental soliton speed. Only positive polarity excitations were observed in our parametric investigation.
Nonlinear Wave Propagation and Solitary Wave Formation in Two-Dimensional Heterogeneous Media
Luna, Manuel
2011-05-01
Solitary wave formation is a well studied nonlinear phenomenon arising in propagation of dispersive nonlinear waves under suitable conditions. In non-homogeneous materials, dispersion may happen due to effective reflections between the material interfaces. This dispersion has been used along with nonlinearities to find solitary wave formation using the one-dimensional p-system. These solitary waves are called stegotons. The main goal in this work is to find two-dimensional stegoton formation. To do so we consider the nonlinear two-dimensional p-system with variable coefficients and solve it using finite volume methods. The second goal is to obtain effective equations that describe the macroscopic behavior of the variable coefficient system by a constant coefficient one. This is done through a homogenization process based on multiple-scale asymptotic expansions. We compare the solution of the effective equations with the finite volume results and find a good agreement. Finally, we study some stability properties of the homogenized equations and find they and one-dimensional versions of them are unstable in general.
Application of artificial neural network to calculation of solitary wave run-up
Institute of Scientific and Technical Information of China (English)
You-xing WEI; Deng-ting WANG; Qing-jun LIU
2010-01-01
The prediction of solitary wave run-up has important practical significance in coastal and ocean engineering,but the calculation precision is limited in the existing models.For improving the calculation precision,a solitary wave run-up calculation model was established based on artificial neural networks in this study A back-propagation(BP)network with one hidden layer was adopted and modified with the additional momentum method and the auto-adjusting learning factor.The model was applied to calculation of solitary wave run-up.The correlation coefficients between the neural network model results and the experimental values was 0.9965.By comparison with the correlation coefficient of 0.9635,between the Synolakis formula calculation results and the experimental values,it is concluded that the neural network model is an effective method for calculation and analysis of solitary wave run-up.
Different Types of Solitary Wave Scattering in the Fermi-Pasta-Ulam Model
Institute of Scientific and Technical Information of China (English)
WEN Zhen-Ying; ZHAO Hong
2005-01-01
@@ We show that the scattering between two solitary waves in the Fermi-Pasta-Ulam model with interaction potential V(x) = αx2/2 + x4/4 can be classified into four types according to the configurations of the solitary waves. For three of the four types, the large solitary wave can lose energy and the small one can gain in average by collision.For the other one type in a special parameter region we encounter an anomalous scattering, i.e. the large solitary wave gains energy and the small one loses energy. Numerical investigations are performed for the anharmonic limit case of α = 0 and the general case of α≠ 0 and comparisons between them are made.
A Polynomial Expansion Method and New General Solitary Wave Solutions to KS Equation
Institute of Scientific and Technical Information of China (English)
PENG Yan-Ze
2003-01-01
Using a polynomial expansion method, the general exact solitary wave solution and singular one areconstructed for the non-linear KS equation. This approach is obviously applicable to a large variety of nonlinear evolution equation.
Singh, Satyavir; Bharuthram, Ramashwar
2016-07-01
Small amplitude electron acoustic solitary waves are studied in a magnetized plasma consisting of hot electrons following Cairn's type non-thermal distribution function and fluid cool electrons, cool ions and an electron beam. Using reductive perturbation technique, the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation is derived to describe the nonlinear evolution of electron acoustic waves. It is observed that the presence of non-thermal electrons plays an important role in determining the existence region of solitary wave structures. Theoretical results of this work is used to model the electrostatic solitary structures observed by Viking satellite. Detailed investigation of physical parameters such as non-thermality of hot electrons, beam electron velocity and temperature, obliquity on the existence regime of solitons will be discussed.
Bypass transition of the bottom boundary layer under solitary wave
Sadek, Mahmoud; Diamessis, Peter; Parras, Luis; Liu, Philip
2015-11-01
The transition to turbulence in the bottom boundary layer (BBL) flow driven by a soliton-like pressure gradient in an oscillating water tunnel (an approximation for the BBL under solitary waves) is investigated using hydrodynamic linear stability theory and DNS. As observed in the laboratory experiment by Sumer et al. (2010), two possible transition scenarios exist. The first scenario is associated with the classical transition resulting from the breakdown of the exponentially growing 2-D Tollmien-Schlichting waves. The alternative scenario; i.e., bypass transition; takes place through formation of localized turbulent spots. The investigation of the latter transition scenario is performed in two steps. The first step consists of reformulating the linear stability analysis in the non-modal framework for the purpose of finding the optimum disturbance characteristics which lead to the formation of those turbulent spots. In the second step, the computed optimum noise structure is inserted in the 3D DNS in order to induce the formation of the turbulent spots and effectively simulate the bypass transition observed experimentally.
The superposition method in seeking the solitary wave solutions to the KdV-Burgers equation
Indian Academy of Sciences (India)
Yuanxi Xie; Jilashi Tang
2006-03-01
In this paper, starting from the careful analysis on the characteristics of the Burgers equation and the KdV equation as well as the KdV-Burgers equation, the superposition method is put forward for constructing the solitary wave solutions of the KdV-Burgers equation from those of the Burgers equation and the KdV equation. The solitary wave solutions for the KdV-Burgers equation are presented successfully by means of this method.
Weakly Two-Dimensional Solitary Waves on Coupled NonlinearTransmission Lines
Institute of Scientific and Technical Information of China (English)
段文山; 洪学仁; 石玉仁; 吕克璞; 孙建安
2002-01-01
We study the nonlinear solitary wave solution under the transverse perturbations for a system of coupled nonlinear electrical transmission lines. In the continuum limit and suitably scaled coordinates, the voltage on the system is described by a modified Zakharov-Kuznetsov equation. The cut-off frequency of the growth rate for the solitary waves under transverse perturbations has been analytically obtained. It is in agreement witl the cases p = 1/2 and p = I vhich have been studied previously.
A unified approach in seeking the solitary wave solutions to sine-Gordon type equations
Institute of Scientific and Technical Information of China (English)
Xie Yuan-Xi; Tang Jia-Shi
2005-01-01
By utilizing the solutions of an auxiliary ordinary differential equation introduced in this paper, we present a simple and direct method to uniformly construct the exact solitary wave solutions for sine-Gordon type equations.As illustrative examples, the exact solitary wave solutions of some physically significant sine-Gordon type equations,including the sine-Gordon equation, double sine-Gordon equation and mKdV-sine-Gordon equation, are investigated by means of this method.
Analytical solitary wave solutions of the nonlinear Kronig-Penney model in photonic structures.
Kominis, Y
2006-06-01
A phase space method is employed for the construction of analytical solitary wave solutions of the nonlinear Kronig-Penney model in a photonic structure. This class of solutions is obtained under quite generic conditions, while the method is applicable to a large variety of systems. The location of the solutions on the spectral band gap structure as well as on the low dimensional space of system's conserved quantities is studied, and robust solitary wave propagation is shown.
Rogue wave variational modelling through the interaction of two solitary waves
Gidel, Floriane; Bokhove, Onno
2016-04-01
The extreme and unexpected characteristics of Rogue waves have made them legendary for centuries. It is only on the 1st of January 1995 that these mariners' tales started to raise scientist's curiosity, when such a wave was recorded in the North Sea; a sudden wall of water hit the Draupner offshore platform, more than twice higher than the other waves, providing evidence of the existence of rogue or freak waves. Since then, studies have shown that these surface gravity waves of high amplitude (at least twice the height of the other sea waves [Dyste et al., 2008]) appear in non-linear dispersive water motion [Drazin and Johnson, 1989], at any depth, and have caused a lot of damage in recent years [Nikolkina and Didenkulova, 2011 ]. So far, most of the studies have tried to determine their probability of occurrence, but no conclusion has been achieved yet, which means that we are currently unenable to predict or avoid these monster waves. An accurate mathematical and numerical water-wave model would enable simulation and observation of this external forcing on boats and offshore structures and hence reduce their threat. In this work, we aim to model rogue waves through a soliton splash generated by the interaction of two solitons coming from different channels at a specific angle. Kodama indeed showed that one way to produce extreme waves is through the intersection of two solitary waves, or one solitary wave and its oblique reflection on a vertical wall [Yeh, Li and Kodama, 2010 ]. While he modelled Mach reflection from Kadomtsev-Petviashvili (KP) theory, we aim to model rogue waves from the three-dimensional potential flow equations and/or their asymptotic equivalent described by Benney and Luke [Benney and Luke, 1964]. These theories have the advantage to allow wave propagation in several directions, which is not the case with KP equations. The initial solitary waves are generated by removing a sluice gate in each channel. The equations are derived through a
Dynamics of coupled light waves and electron-acoustic waves.
Shukla, P K; Stenflo, L; Hellberg, M
2002-08-01
The nonlinear interaction between coherent light waves and electron-acoustic waves in a two-electron plasma is considered. The interaction is governed by a pair of equations comprising a Schrödinger-like equation for the light wave envelope and a driven (by the light pressure) electron-acoustic wave equation. The newly derived nonlinear equations are used to study the formation and dynamics of envelope light wave solitons and light wave collapse. The implications of our investigation to space and laser-produced plasmas are pointed out.
The Korteweg-de Vries-Zakharov-Kuznetsov equation for electron-acoustic waves
International Nuclear Information System (INIS)
Motivated by a recent paper [Phys. Plasmas 7, 2987 (2000)] highlighting the potential importance of the electron-acoustic wave in interpreting the solitary waves observed by high time resolution measurements of the electric field in the auroral region, the effect of a magnetic field on weakly nonlinear electron-acoustic waves is investigated. A Korteweg-de Vries-Zakharov-Kuznetsov (KdV-ZK) equation is derived for a plasma comprised of cool and hot electrons and a species of fluid ions. Two models are employed for the ions: magnetized and unmagnetized. When the ions are magnetized the frequency constraints imposed upon the electron-acoustic wave packet prove to be too limiting to be of general use. The second model, which treats the ions as a stationary neutralizing background, overcomes the restrictions imposed by the former and is more fitting for the frequency domain of the electron-acoustic wave. Plane and ellipsoidal soliton solutions are admitted by the KdV-ZK equation, the latter perhaps able to explain some of the two dimensional features of the solitary waves observed in the Earth's high altitude auroral region. Both models for the ions predict only negative potential solitons. It is discussed how the plasma model might be adapted to produce positive potential solitons
Characteristic behaviour of Kadomtsev-Petviashvili solitary waves and their stability in plasmas
International Nuclear Information System (INIS)
By employing the reductive perturbation technique, Kadomtsev-Petviashvili (K-P) equation has been derived with a view to know the salient features of soliton propagation in multi-component plasma. A proposed method called as tanh-method has been employed to find the soliton solution of the non-linear K-P wave equation and has shown successfully the existence of various soliton propagation in plasma. The main aim of using the formalism of tanh-method has been given to modify the non-linear wave equation into an ordinary differential equation which has been solved ultimately by Frobenius method. In contrast to the earlier predictions, it has been shown that the multi-component plasma might not always sustain the compressive or rarefactive soliton even though the plasma consists of multi-temperature electrons. The existence depends on the control of plasma configuration which might be the advanced knowledge to observe the soliton formation in laboratory and space plasmas. Moreover, because of the higher order non-linearity, the observations sieved various plasma acoustic modes which could be of interest to relate in space plasmas. Finally, it has been shown that the solitary wave propagation though suffers from the bifurcation due to the singularity in the propagation, despite all, the study, based on the perturbation procedure, confirmed the stability of the soliton propagation irrespective of their different natures. (author)
Dust-acoustic solitary structures in plasmas with nonthermal electrons and positive dust
Directory of Open Access Journals (Sweden)
F. Verheest
2008-07-01
Full Text Available Large dust-acoustic solitons and kinks in dusty plasmas with positive cold dust, nonthermally distributed electrons and Boltzmann ions have been studied in a systematic way, to delimit their compositional parameter space. The existence domain of positive solitons is limited by infinite dust compression, of negative ones by the occurrence of potential kinks, provided the electrons are sufficiently nonthermal and there is sufficient positive charge on the dust. There is a parameter range where both negative and positive solitary structures coexist.
Focusing of Acoustic Waves through Acoustic Materials with Subwavelength Structures
Xiao, Bingmu
2013-05-01
In this thesis, wave propagation through acoustic materials with subwavelength slits structures is studied. Guided by the findings, acoustic wave focusing is achieved with a specific material design. By using a parameter retrieving method, an effective medium theory for a slab with periodic subwavelength cut-through slits is successfully derived. The theory is based on eigenfunction solutions to the acoustic wave equation. Numerical simulations are implemented by the finite-difference time-domain (FDTD) method for the two-dimensional acoustic wave equation. The theory provides the effective impedance and refractive index functions for the equivalent medium, which can reproduce the transmission and reflection spectral responses of the original structure. I analytically and numerically investigate both the validity and limitations of the theory, and the influences of material and geometry on the effective spectral responses are studied. Results show that large contrasts in impedance and density are conditions that validate the effective medium theory, and this approximation displays a better accuracy for a thick slab with narrow slits in it. Based on the effective medium theory developed, a design of a at slab with a snake shaped" subwavelength structure is proposed as a means of achieving acoustic focusing. The property of focusing is demonstrated by FDTD simulations. Good agreement is observed between the proposed structure and the equivalent lens pre- dicted by the theory, which leads to robust broadband focusing by a thin at slab.
Linear Stability of the boundary layer under a solitary wave
Verschaeve, Joris C G
2013-01-01
A theoretical and numerical analysis of the linear stability of the boundary layer flow under a solitary wave is presented. In the present work, the nonlinear boundary layer equations are solved. The result is compared to the linear boundary layer solution in Liu et al. (2007) reveal- ing that both profiles are disagreeing more than has been found before. A change of frame of reference has been used to allow for a classical linear stability analysis without the need to redefine the notion of stability for this otherwise unsteady flow. For the linear stability the Orr-Sommerfeld equation and the parabolic stability equation were used. The results are compared to key results of inviscid stability theory and validated by means of a direct numerical simulation using a Legendre-Galerkin spectral ele- ment Navier-Stokes solver. Special care has been taken to ensure that the numerical results are valid. Linear stability predicts that the boundary layer flow is unstable for the entire parameter range considered, conf...
Integrability: mathematical methods for studying solitary waves theory
Wazwaz, Abdul-Majid
2014-03-01
In recent decades, substantial experimental research efforts have been devoted to linear and nonlinear physical phenomena. In particular, studies of integrable nonlinear equations in solitary waves theory have attracted intensive interest from mathematicians, with the principal goal of fostering the development of new methods, and physicists, who are seeking solutions that represent physical phenomena and to form a bridge between mathematical results and scientific structures. The aim for both groups is to build up our current understanding and facilitate future developments, develop more creative results and create new trends in the rapidly developing field of solitary waves. The notion of the integrability of certain partial differential equations occupies an important role in current and future trends, but a unified rigorous definition of the integrability of differential equations still does not exist. For example, an integrable model in the Painlevé sense may not be integrable in the Lax sense. The Painlevé sense indicates that the solution can be represented as a Laurent series in powers of some function that vanishes on an arbitrary surface with the possibility of truncating the Laurent series at finite powers of this function. The concept of Lax pairs introduces another meaning of the notion of integrability. The Lax pair formulates the integrability of nonlinear equation as the compatibility condition of two linear equations. However, it was shown by many researchers that the necessary integrability conditions are the existence of an infinite series of generalized symmetries or conservation laws for the given equation. The existence of multiple soliton solutions often indicates the integrability of the equation but other tests, such as the Painlevé test or the Lax pair, are necessary to confirm the integrability for any equation. In the context of completely integrable equations, studies are flourishing because these equations are able to describe the
Dynamic motions of ion acoustic waves in plasmas with superthermal electrons
Energy Technology Data Exchange (ETDEWEB)
Saha, Asit, E-mail: asit_saha123@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology (India); Chatterjee, Prasanta [Department of Mathematics, Siksha Bhavana, Visva Bharati University (India); Wong, C.S. [Plasma Technology Research Centre, Department of Physics, University of Malaya, Kuala Lampur (Malaysia)
2015-12-15
The dynamic motions of ion acoustic waves an unmagnetized plasma with superthermal (q-non extensive) electrons are investigated employing the bifurcation theory of planar dynamical systems through direct approach. Using traveling wave transformation and initial conditions, basic equations are transformed to a planar dynamical system. Using numerical computations, all possible phase portraits of the dynamical system are presented. Corresponding to homoclinic and periodic orbits of the phase portraits, two new analytical forms of solitary and periodic wave solutions are derived depending on the non extensive parameter q and speed v of the traveling wave. Considering an external periodic perturbation, the quasiperiodic and chaotic motions of ion acoustic waves are presented. Depending upon different ranges of non extensive parameter q, the effect of q is shown on quasiperiodic and chaotic motions of ion acoustic waves with fixed value of v. It is seen that the unperturbed dynamical system has the solitary and periodic wave solutions, but the perturbed dynamical system has the quasiperiodic and chaotic motions with same values of parameters q and v. (author)
Institute of Scientific and Technical Information of China (English)
CHEN Yong; YAN Zhen-Ya; LI Biao; ZHANG Hong-Qing
2002-01-01
In this paper, we study the generalized coupled Hirota Satsuma KdV system by using the new generalizedtransformation in homogeneous balance method. As a result, many explicit exact solutions, which contain new solitarywave solutions, periodic wave solutions, and the combined formal solitary wave solutions, and periodic wave solutions,are obtained.
The propagation of a solitary wave over seabed mud of the Voigt model
Xia, YueZhang; Zhu, KeQin
2012-01-01
In shallow water, seabed mud can dissipate the energy of surface gravity waves effectively. In this paper, solitary wave attenuation induced by seabed mud is studied based on a two-layered system, in which the water is assumed to be inviscid and the mud layer is described by the Voigt model. A set of Boussinesq-type equations suitable for solitary waves over the mud of the Voigt model is established, by combining the perturbation analysis and the Laplace transformation. Degenerating into the case of Newtonian model, our Boussinesq-type equations are equivalent to those of Liu and Chan (2007), while the term indicating mud influence is greatly simplified. Based on the equations, the attenuation of solitary waves is studied. An evolution equation of wave amplitude is obtained and the development of mud velocity profiles is discussed. The modal analysis shows that the first mode always dominates mud dynamics. The results are also compared with those of the Maxwell model.
Head-on collision of large amplitude internal solitary waves of the first mode
Terletska, Kateryna; Maderich, Vladimir; Brovchenko, Igor; Jung, Kyung Tae; Talipova, Tatiana
2016-04-01
The dynamics and energetics of a frontal collision of internal solitary waves of depression and elevation of moderate and large amplitudes propagating in a two-layer stratified fluid are studied numerically in frame of the Navier-Stokes equations. It was considered symmetric and asymmetric head-on collisions. We propose the dimensionless characteristic of the wave collision ξ that is the ratio of the wave steepnesses. Wave runup normalized on the amplitude of incoming wave as function of the waves steepness is proposed. Interval 01 corresponds to the larger wave in the case of asymmetric collision. Results of modeling were compared with the results of laboratory experiments [1]. It was shown that the frontal collision of internal solitary waves of moderate amplitude leads to a small phase shift and to the generation of dispersive wavetrain trailing behind transmitted solitary wave. The phase shift grows with increasing amplitudes of the interacting waves and approaches the limiting value when amplitudes of the waves are equal to the upper/lower layer for waves of depression/elevation. The deviation of the maximum wave height during collision from the twice the amplitude are maximal when wave amplitudes are equal to the upper/lower layer for waves of depression/elevation, then it decays with growth of amplitudes of interacting waves. It was found that the interaction of waves of large amplitude leads to the shear instability and the formation of Kelvin - Helmholtz vortices in the interface layer, however, subsequently waves again become stable. References [1] R.-C. Hsu, M. H. Cheng, C.-Y. Chen, Potential hazards and dynamical analysis of interfacial solitary wave interactions. Nat Hazards. 65 (2013) 255-278
RANS-VOF solver for solitary wave run-up on a circular cylinder
Cao, Hong-jian; Wan, De-cheng
2015-04-01
Simulation of solitary wave run-up on a vertical circular cylinder is carried out in a viscous numerical wave tank developed based on the open source codes OpenFOAM. An incompressible two-phase flow solver naoe-FOAM-SJTU is used to solve the Reynolds-Averaged Navier-Stokes (RANS) equations with the SST k- ω turbulence model. The PISO algorithm is utilized for the pressure-velocity coupling. The air-water interface is captured via Volume of Fluid (VOF) technique. The present numerical model is validated by simulating the solitary wave run-up and reflected against a vertical wall, and solitary wave run-up on a vertical circular cylinder. Comparisons between numerical results and available experimental data show satisfactory agreement. Furthermore, simulations are carried out to study the solitary wave run-up on the cylinder with different incident wave height H and different cylinder radius a. The relationships of the wave run-up height with the incident wave height H, cylinder radius a are analyzed. The evolutions of the scattering free surface and vortex shedding are also presented to give a better understanding of the process of nonlinear wave-cylinder interaction.
RANS-VOF Solver for Solitary Wave Run-up on A Circular Cylinder
Institute of Scientific and Technical Information of China (English)
曹洪建; 万德成
2015-01-01
Simulation of solitary wave run-up on a vertical circular cylinder is carried out in a viscous numerical wave tank developed based on the open source codes OpenFOAM. An incompressible two-phase flow solver naoe-FOAM-SJTU is used to solve the Reynolds-Averaged Navier–Stokes (RANS) equations with the SST k-wturbulence model. The PISO algorithm is utilized for the pressure-velocity coupling. The air-water interface is captured via Volume of Fluid (VOF) technique. The present numerical model is validated by simulating the solitary wave run-up and reflected against a vertical wall, and solitary wave run-up on a vertical circular cylinder. Comparisons between numerical results and available experimental data show satisfactory agreement. Furthermore, simulations are carried out to study the solitary wave run-up on the cylinder with different incident wave height H and different cylinder radius a. The relationships of the wave run-up height with the incident wave height H, cylinder radius a are analyzed. The evolutions of the scattering free surface and vortex shedding are also presented to give a better understanding of the process of nonlinear wave-cylinder interaction.
Burgers-Korteweg-de Vries equation and its traveling solitary waves
Institute of Scientific and Technical Information of China (English)
Zhao-sheng FENG; Qing-guo MENG
2007-01-01
The Burgers-Korteweg-de Vries equation has wide applications in physics, engineering equation has neither nontrivial bell-profile traveling solitary waves, nor periodic waves. In the present paper, we show two approaches for the study of traveling solitary waves of the Burgers-Korteweg-de Vries equation: one is a direct method which involves a few coordinate transformations, and the other is the Lie group method. Our study indicates that the Burgers-Korteweg-de Vries equation indirectly admits one-parameter Lie groups of transformations with certain parametric conditions and a traveling solitary wave solution with an arbitrary velocity is obtained accordingly. Some incorrect statements in the recent literature are clarified.
Burgers-Korteweg-de Vries equation and its traveling solitary waves
Institute of Scientific and Technical Information of China (English)
2007-01-01
The Burgers-Korteweg-de Vries equation has wide applications in physics, engineering and fluid mechanics. The Poincare phase plane analysis reveals that the Burgers-Korteweg-de Vries equation has neither nontrivial bell-profile traveling solitary waves, nor periodic waves. In the present paper, we show two approaches for the study of traveling solitary waves of the Burgers-Korteweg-de Vries equation: one is a direct method which involves a few coordinate transformations, and the other is the Lie group method. Our study indicates that the Burgers-Korteweg-de Vries equation indirectly admits one-parameter Lie groups of transformations with certain parametric conditions and a traveling solitary wave solution with an arbitrary velocity is obtained accordingly. Some incorrect statements in the recent literature are clarified.
Algebraic Rossby Solitary Waves Excited by Non-Stationary External Source
Institute of Scientific and Technical Information of China (English)
杨红卫; 尹宝树; 董焕河; 时云龙
2012-01-01
The paper deals with the effects of non-stationary external source forcing and dissipation on algebraic Rossby solitary waves. From quasi-geostrophic potential vorticity equation, basing on the multiple-scale method, an inhomogeneous Korteweg-de Vries-Benjamin Ono Burgers （KdV-B-O-Burgers） equation is obtained. This equation has not been previously derived for Rossby waves. By analysis and calculation, four conservation laws associated with the above equation are first obtained. With the help of pseudo-spectral method, the waterfall plots are obtained and the evolutional characters of algebraic Rossby solitary waves are studied. The results show that non-stationary external source and dissipation have great effect on the generation and evolution of algebraic solitary Rossby waves.
Analysis of solitary wave impulses in granular chains using ultrasonic excitation
Yang, J.; Hutchins, D. A.; Akanji, O.; Thomas, P. J.; Davis, L. A. J.; Harput, S.; Gelat, P.; Freear, S.; Saffari, N.
2016-06-01
The propagation of broad bandwidth solitary wave impulses, generated within granular chains by narrow bandwidth ultrasonic excitation, is studied in detail. Theoretical predictions are compared to experimental results. It is demonstrated that the observed effects result from a sum of a solitary wave traveling out from the source with a wave that reflects from the far end of the chain. It is shown that this combination, when used with an excitation in the form of a long-duration tone burst, encourages the generation of multiple impulses with a characteristic periodicity. This study shows that the properties of the chain structure and the excitation can be adjusted so as to generate ultrasonic solitary wave impulses with a high amplitude and known frequency content, which are of interest in applications such as biomedical ultrasound.
Ion acceleration in a solitary wave by an intense picosecond laser pulse.
Zhidkov, A; Uesaka, M; Sasaki, A; Daido, H
2002-11-18
Acceleration of ions in a solitary wave produced by shock-wave decay in a plasma slab irradiated by an intense picosecond laser pulse is studied via particle-in-cell simulation. Instead of exponential distribution as in known mechanisms of ion acceleration from the target surface, these ions accelerated forwardly form a bunch with relatively low energy spread. The bunch is shown to be a solitary wave moving over expanding plasma; its velocity can exceed the maximal velocity of ions accelerated forward from the rear side of the target.
Exciton transport by surface acoustic waves
Rudolph, J.; Hey, R.; Santos, P. V.
2007-05-01
Long-range acoustic transport of excitons in GaAs quantum wells (QWs) is demonstrated. The mobile strain field of a surface acoustic wave creates a dynamic lateral type I modulation of the conduction and valence bands in a double-quantum-well (DQW) structure. This mobile potential modulation transports long-living indirect excitons in the DQW over several hundreds of μm.
Bai, X.
2015-12-01
The internal solitary wave (ISW) fission process is delineated in the northeastern South China Sea (SCS) for the first time through field observations, satellite detections and theoretical numerical simulations. Observations from a mooring station with Acoustic Doppler Current Profiler (ADCP) document the fission appearance of a group of ISWs near the continental shelf. Evidence from Moderate Resolution Imaging Spectroradiometer (MODIS) true-colour images supports the field measurements. Initialized by the parameters from observations, a two-layer numerical model based on the Regularized Long-Wave (RLW) equation in a homogeneous thermocline is employed to analyze the propagation and evolution of the ISWs, which shows results similar to the observations. The simulation results indicate that ISWs usually fission near the critical region (the coefficient of the nonlinear term, α≈0). Further theoretical analysis is expanded to the condition in an inhomogeneous thermocline, and the number of ISW fission is calculated and discussed.
Imaging of Acoustic Waves in Sand
Energy Technology Data Exchange (ETDEWEB)
Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall
2003-08-01
There is considerable interest in detecting objects such as landmines shallowly buried in loose earth or sand. Various techniques involving microwave, acoustic, thermal and magnetic sensors have been used to detect such objects. Acoustic and microwave sensors have shown promise, especially if used together. In most cases, the sensor package is scanned over an area to eventually build up an image or map of anomalies. We are proposing an alternate, acoustic method that directly provides an image of acoustic waves in sand or soil, and their interaction with buried objects. The INEEL Laser Ultrasonic Camera utilizes dynamic holography within photorefractive recording materials. This permits one to image and demodulate acoustic waves on surfaces in real time, without scanning. A video image is produced where intensity is directly and linearly proportional to surface motion. Both specular and diffusely reflecting surfaces can be accomodated and surface motion as small as 0.1 nm can be quantitatively detected. This system was used to directly image acoustic surface waves in sand as well as in solid objects. Waves as frequencies of 16 kHz were generated using modified acoustic speakers. These waves were directed through sand toward partially buried objects. The sand container was not on a vibration isolation table, but sat on the lab floor. Interaction of wavefronts with buried objects showed reflection, diffraction and interference effects that could provide clues to location and characteristics of buried objects. Although results are preliminary, success in this effort suggests that this method could be applied to detection of buried landmines or other near-surface items such as pipes and tanks.
Active micromixer using surface acoustic wave streaming
Branch; Darren W. , Meyer; Grant D. , Craighead; Harold G.
2011-05-17
An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.
Topological charge pump by surface acoustic waves
Yi, Zheng; Shi-Ping, Feng; Shi-Jie, Yang
2016-06-01
Quantized electron pumping by the surface acoustic wave across barriers created by a sequence of split metal gates is interpreted from the viewpoint of topology. The surface acoustic wave serves as a one-dimensional periodical potential whose energy spectrum possesses the Bloch band structure. The time-dependent phase plays the role of an adiabatic parameter of the Hamiltonian which induces a geometrical phase. The pumping currents are related to the Chern numbers of the filled bands below the Fermi energy. Based on this understanding, we predict a novel effect of quantized but non-monotonous current plateaus simultaneously pumped by two homodromous surface acoustic waves. Project supported by the National Natural Science Foundation of China (Grant No. 11374036) and the National Basic Research Program of China (Grant No. 2012CB821403).
NUMERICAL SIMULATION OF SOLITARY WAVE RUN-UP AND OVERTOPPING USING BOUSSINESQ-TYPE MODEL
Institute of Scientific and Technical Information of China (English)
TSUNG Wen-Shuo; HSIAO Shih-Chun; LIN Ting-Chieh
2012-01-01
In this article,the use of a high-order Boussinesq-type model and sets of laboratory experiments in a large scale flume of breaking solitary waves climbing up slopes with two inclinations are presented to study the shoreline behavior of breaking and non-breaking solitary waves on plane slopes.The scale effect on run-up height is briefly discussed.The model simulation capability is well validated against the available laboratory data and present experiments.Then,serial numerical tests are conducted to study the shoreline motion correlated with the effects of beach slope and wave nonlinearity for breaking and non-breaking waves.The empirical formula proposed by Hsiao et al.for predicting the maximum run-up height of a breaking solitary wave on plane slopes with a wide range of slope inclinations is confirmed to be cautious.Furthermore,solitary waves impacting and overtopping an impermeable sloping seawall at various water depths are investigated.Laboratory data of run-up height,shoreline motion,free surface elevation and overtopping discharge are presented.Comparisons of run-up,run-down,shoreline trajectory and wave overtopping discharge are made.A fairly good agreement is seen between numerical results and experimental data.It elucidates that the present depth-integrated model can be used as an efficient tool for predicting a wide spectrum of coastal problems.
Kodaira, Tsubasa; Waseda, Takuji
2013-04-01
We have conducted ADCP and CTD measurements from 31/8/2010 to 2/9/2010 at the Miyake Island, located approximately 180 km south of Tokyo. The Kuroshio Current approached the island in this period, and the PALSAR image showed parabolic bright line upstream of the island. This bright line may be a surface signature of large amplitude internal solitary wave. Although our measurements did not explicitly show evidence of the internal solitary wave, critical condition might have been satisfied because of the Kuroshio Current and strong seasonal thermocline. To discover the generation mechanism of the large amplitude internal solitary wave at the Miyake Island, we have conducted non-hydrostatic numerical simulation with the MITgcm. A simple box domain, with open boundaries at all sides, is used. The island is simplified to circular cylinder or Gaussian Bell whose radius is 3km at ocean surface level. The size of the domain is 40kmx40kmx500m for circular cylinder cases and 80kmx80kmx500m for Gaussian bell cases. By looking at our CTD data, we have chosen for initial and boundary conditions a tanh function for vertical temperature profile. Salinity was kept constant for simplicity. Vertical density profile is also described by tanh function because we adopt linear type of equation of state. Vertical velocity profile is constant or linearly changed with depth; the vertical mean speed corresponds to the linear phase speed of the first baroclinic mode obtained by solving the eigen-value problem. With these configurations, we have conducted two series of simulations: shear flow through cylinder and uniform flow going through Gaussian Bell topography. Internal solitary waves were generated in front of the cylinder for the first series of simulations with shear flow. The generated internal waves almost purely consisted of 1st baroclinic component. Their intensities were linearly related with upstream vertical shear strength. As the internal solitary wave became larger, its width
Institute of Scientific and Technical Information of China (English)
张卫国
2003-01-01
In this paper, we have obtained the bell-type and kink-type solitary wave solutions of the generalized symmetric regularized long-wave equations with high-order nonlinear terms by means of proper transformation and undetermined assumption method.
A mechanical analog of the two-bounce resonance of solitary waves: Modeling and experiment
Goodman, Roy H.; Rahman, Aminur; Bellanich, Michael J.; Morrison, Catherine N.
2015-04-01
We describe a simple mechanical system, a ball rolling along a specially-designed landscape, which mimics the well-known two-bounce resonance in solitary wave collisions, a phenomenon that has been seen in countless numerical simulations but never in the laboratory. We provide a brief history of the solitary wave problem, stressing the fundamental role collective-coordinate models played in understanding this phenomenon. We derive the equations governing the motion of a point particle confined to such a surface and then design a surface on which to roll the ball, such that its motion will evolve under the same equations that approximately govern solitary wave collisions. We report on physical experiments, carried out in an undergraduate applied mathematics course, that seem to exhibit the two-bounce resonance.
Institute of Scientific and Technical Information of China (English)
段文山
2002-01-01
By considering the vortex-like ion distribution, we know that the nonlinear dust acoustic wave can be described by the modified Korteweg-de Vries equation. If there are high-order transverse perturbations in this system, the governing equation for this system is the modified Kadomtsev-Petviashvili equation. We also find that for this system under the transverse perturbation the one-dimensional solitary wave solution is stable.
Institute of Scientific and Technical Information of China (English)
YANG Qiu-Ying; MA Song-Hua; ZHANG Ying-Yue; FANG Jian-Ping; CHEN Tian-Lun; HONG Bi-Hai; ZHENG Chun-Long
2008-01-01
By means of an extended mapping approach and a linear variable separation approach, a new family of exact solutions of the (3+1)-dimensional Jimbo-Miwa system is derived. Based on the derived solitary wave solution, we obtain some special localized excitations and study the interactions between two solitary waves of the system.
Collaborative Research: Dynamics of Electrostatic Solitary Waves on Current Layers
Energy Technology Data Exchange (ETDEWEB)
Pickett, Jolene S.
2012-10-31
The research carried out under the subject grant has provided insight into the generation of Electrostatic Solitary Waves (ESWs), which are nonlinear structures observed in space plasma data. These ESWs, appearing as pulses in the electric field time series data, represent the presence of several hundred meters to kilometer size positive potential structures, similar to champagne bubbles, where the electrons have been depleted, and which travel along Earth's magnetic field lines. The laboratory experiments carried out at the UCLA LAPD under the grant allowed us the opportunity to change various plasma and field conditions within the plasma device, and experiment with injection of suprathermal electron beams, in order to create ESWs. This then allowed us to determine the most likely method of generation of the ESWs. By comparing the properties of the ESWs observed in the LAPD to those observed in space and the plasma and field conditions under which those ESWs were observed in both locations, we were able to evaluate various ESW generation mechanisms. The findings of the laboratory experiments are that ESWs are generated through a lower hybrid instability. The ESWs observed in Earth's auroral current regions have similar characteristics to those generated by the laboratory when referenced to basic plasma and field characteristics, leading us to the conclusion that the lower hybrid drift instability is certainly a possibility for generation of the ESWs, at least in the auroral (northern/southern lights) regions. Due to space instrumentation insufficiencies and the limitations on telemetry, and thus poor time resolution, it is not possible to determine absolutely what generates these bubbles in space, but the laboratory experiments and supporting simulations have helped us to further our understanding of the processes under which they are generated. The public benefits from the findings of this research because the research is focused on current layers
Directory of Open Access Journals (Sweden)
O. D. Shishkina
2013-10-01
Full Text Available An interaction of internal solitary waves with the shelf edge in the time periods related to the presence of a pronounced seasonal pycnocline in the Red Sea and in the Alboran Sea is analysed via satellite photos and SAR images. Laboratory data on transformation of a solitary wave of depression while passing along the transverse bottom step were obtained in a tank with a two-layer stratified fluid. The certain difference between two characteristic types of hydrophysical phenomena was revealed both in the field observations and in experiments. The hydrological conditions for these two processes were named the "deep" and the "shallow" shelf respectively. The first one provides the generation of the secondary periodic short internal waves – "runaway" edge waves – due to change in the polarity of a part of a soliton approaching the shelf normally. Another one causes a periodic shear flow in the upper quasi-homogeneous water layer with the period of incident solitary wave. The strength of the revealed mechanisms depends on the thickness of the water layer between the pycnocline and the shelf bottom as well as on the amplitude of the incident solitary wave.
From nonlocal gap solitary waves to bound states in periodic media
Akylas, T R; Yang, Jianke
2011-01-01
Solitary waves in one-dimensional periodic media are discussed employing the nonlinear Schr\\"odinger equation with a spatially periodic potential as a model. This equation admits two families of gap solitons that bifurcate from the edges of Bloch bands in the linear wave spectrum. These fundamental solitons may be positioned only at specific locations relative to the potential; otherwise, they become nonlocal owing to the presence of growing tails of exponentially-small amplitude with respect to the wave peak amplitude. Here, by matching the tails of such nonlocal solitary waves, higher-order locally confined gap solitons, or bound states, are constructed. Details are worked out for bound states comprising two nonlocal solitary waves in the presence of a sinusoidal potential. A countable set of bound-state families, characterized by the separation distance of the two solitary waves, is found, and each family features three distinct solution branches that bifurcate near Bloch-band edges at small, but finite, a...
Energy Technology Data Exchange (ETDEWEB)
Kichigin, G. N., E-mail: king@iszf.irk.ru [Russian Academy of Sciences, Institute of Solar–Terrestrial Physics, Siberian Branch (Russian Federation)
2016-01-15
Solutions describing solitary fast magnetosonic (FMS) waves (FMS solitons) in cold magnetized plasma are obtained by numerically solving two-fluid hydrodynamic equations. The parameter domain within which steady-state solitary waves can propagate is determined. It is established that the Mach number for rarefaction FMS solitons is always less than unity. The restriction on the propagation velocity leads to the limitation on the amplitudes of the magnetic field components of rarefaction solitons. It is shown that, as the soliton propagates in plasma, the transverse component of its magnetic field rotates and makes a complete turn around the axis along which the soliton propagates.
Stability and Instability of the KDV Solitary Wave Under the KP-I Flow
Rousset, Frederic; Tzvetkov, Nikolay
2012-07-01
We consider the KP-I and gKP-I equations in {{{R}} × ({{R}}/2π{{Z}})}. We prove that the KdV soliton with subcritical speed 0 Stud 163:181-211, 2007). For supercritical speeds c > c*, in the spirit of the work by Duyckaerts and Merle (GAFA 18:1787-1840, 2009), we sharpen our previous instability result and construct a global solution which is different from the solitary wave and its translates and which converges to the solitary wave as time goes to infinity. This last result also holds for the gKP-I equation.
Solitary Density Waves for Improved Traffic Flow Model with Variable Brake Distances
Institute of Scientific and Technical Information of China (English)
朱文兴; 丁瑞玲
2012-01-01
Traffic flow model is improved by introducing variable brake distances with varying slopes. Stability of the traffic flow on a gradient is analyzed and the neutral stability condition is obtained. The KdV （Korteweg-de Vries） equation is derived the use of nonlinear analysis and soliton solution is obtained in the meta-stable region. Solitary density waves are reproduced in the numerical simulations. It is found that as uniform headway is less than the safety distance solitary wave exhibits upward form, otherwise it exhibits downward form. In general the numerical results are in good agreement with the analytical results.
Energy Technology Data Exchange (ETDEWEB)
Rehman, M. A.; Qureshi, M. N. S. [Department of Physics, GC University, Kachery Road, Lahore 54000 (Pakistan); Shah, H. A. [Department of Physics, Forman Christian College, Ferozepur Road, Lahore 54600 (Pakistan); Masood, W. [COMSATS, Institute of Information Technology, Park Road, Chak Shehzad, Islamabad 44000 (Pakistan); National Centre for Physics (NCP) Shahdra Valley Road, Islamabad (Pakistan)
2015-10-15
Nonlinear circularly polarized Alfvén waves are studied in magnetized nonrelativistic, relativistic, and ultrarelativistic degenerate Fermi plasmas. Using the quantum hydrodynamic model, Zakharov equations are derived and the Sagdeev potential approach is used to investigate the properties of the electromagnetic solitary structures. It is seen that the amplitude increases with the increase of electron density in the relativistic and ultrarelativistic cases but decreases in the nonrelativistic case. Both right and left handed waves are considered, and it is seen that supersonic, subsonic, and super- and sub-Alfvénic solitary structures are obtained for different polarizations and under different relativistic regimes.
Broadband acoustic cloak for ultrasound waves.
Zhang, Shu; Xia, Chunguang; Fang, Nicholas
2011-01-14
Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely, serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Because of the nonresonant nature of the building elements, this low-loss (∼6 dB/m) cylindrical cloak exhibits invisibility over a broad frequency range from 52 to 64 kHz. Furthermore, our experimental study indicates that this design approach should be scalable to different acoustic frequencies and offers the possibility for a variety of devices based on coordinate transformation.
Some Applications of Surface Acoustic Wave Sensors
Institute of Scientific and Technical Information of China (English)
2000-01-01
The paper describes the evaluation of thin amorphous magnetic film by using of surface acoustic waves on piezo electric substrate. The obtained experimental data show strong dependence of material parameters on the annealing temperature. The mixed ferromagnetic/SAW devices for electronic applications will be also discussed.
Wave Phenomena in an Acoustic Resonant Chamber
Smith, Mary E.; And Others
1974-01-01
Discusses the design and operation of a high Q acoustical resonant chamber which can be used to demonstrate wave phenomena such as three-dimensional normal modes, Q values, densities of states, changes in the speed of sound, Fourier decomposition, damped harmonic oscillations, sound-absorbing properties, and perturbation and scattering problems.…
Binary collision approximation for solitary waves in a Y-shaped granular chain
Institute of Scientific and Technical Information of China (English)
Chen Qiong; Yang Xian-Qing; Zhao Xin-Yin; Wang Zhen-Hui; Zhao Yue-Min
2013-01-01
We implement a binary collision approximation to study solitary wave propagation in a two-dimensional double Y-shaped granular chain.The solitary wave was transmitted and reflected when it met the interface of the bifurcated branches of the Y-shaped granular chains.We obtain the analytic results of the ratios of the transmitted and reflected speeds to the incident speed of the solitary wave,the maximum force between the two neighbor beads in a solitary wave,and the total time taken by the pulse to pass through each branch.All of the analytic results are in good agreement with the experimental observations from Daraio et al.[Phys.Rev.E 82 036603 (2010)].Moreover,we also discuss the delay effects on the arrival of split pulses,and predict the recombination of the split waves traveling in branches in the final stem of asymmetric systems.The prediction of pulse recombination is verified by our numerical results.
Linear and nonlinear heavy ion-acoustic waves in a strongly coupled plasma
Energy Technology Data Exchange (ETDEWEB)
Ema, S. A., E-mail: ema.plasma@gmail.com; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh); Hossen, M. R. [Deparment of Natural Sciences, Daffodil International University, Sukrabad, Dhaka-1207 (Bangladesh)
2015-09-15
A theoretical study on the propagation of linear and nonlinear heavy ion-acoustic (HIA) waves in an unmagnetized, collisionless, strongly coupled plasma system has been carried out. The plasma system is assumed to contain adiabatic positively charged inertial heavy ion fluids, nonextensive distributed electrons, and Maxwellian light ions. The normal mode analysis is used to study the linear behaviour. On the other hand, the well-known reductive perturbation technique is used to derive the nonlinear dynamical equations, namely, Burgers equation and Korteweg-de Vries (K-dV) equation. They are also numerically analyzed in order to investigate the basic features of shock and solitary waves. The adiabatic effects on the HIA shock and solitary waves propagating in such a strongly coupled plasma are taken into account. It has been observed that the roles of the adiabatic positively charged heavy ions, nonextensivity of electrons, and other plasma parameters arised in this investigation have significantly modified the basic features (viz., polarity, amplitude, width, etc.) of the HIA solitary/shock waves. The findings of our results obtained from this theoretical investigation may be useful in understanding the linear as well as nonlinear phenomena associated with the HIA waves both in space and laboratory plasmas.
Advection of pollutants by internal solitary waves in oceanic and atmospheric stable stratifications
Directory of Open Access Journals (Sweden)
G. W. Haarlemmer
1998-01-01
Full Text Available When a pollutant is released into the ocean or atmosphere under turbulent conditions, even a steady release is captured by large eddies resulting in localized patches of high concentration of the pollutant. If such a cloud of pollutant subsequently enters a stable stratification-either a pycnocline or thermocline-then internal waves are excited. Since large solitary internal waves have a recirculating core, pollutants may be trapped in the sclitary wave, and advected large distances through the waveguide provided by the stratification. This paper addresses the mechanisms, through computer and physical simulation, by which a localized release of a dense pollutant results in solitary waves that trap the pollutant or disperse the pollutant faster than in the absence of the waves.
Solitary waves and stable analysis for the quintic discrete nonlinear Schrödinger equation
Zhang, Jinliang; Liu, Zhiguo; Li, Siwei; Wang, Mingliang
2012-07-01
The quintic discrete nonlinear Schrödinger equation (QDNLS) is an important model for describing the propagation of discrete self-trapped beams in an array of weakly coupled nonlinear optical waveguides. In this paper, the QDNLS is studied and bright solitons, dark solitons, alternating phase solitons, trigonometric function periodic wave solutions and rational wave solutions with arbitrary parameters are obtained using the extended G'/G-expansion method. The linear stability of the bright soliton, the dark soliton and the rational wave solution is analyzed using the perturbation method, and the conditions that stable solitary wave solutions satisfy are presented. The stable solitary wave solutions to the QDNLS are useful in understanding the complicated physical phenomena described by QDNLS.
Measuring Acoustic Nonlinearity by Collinear Mixing Waves
Liu, M.; Tang, G.; Jacobs, L. J.; Qu, J.
2011-06-01
It is well known that the acoustic nonlinearity parameter β is correlated to fatigue damage in metallic materials. Various methods have been developed to measure β. One of the most often used methods is the harmonic generation technique, in which β is obtained by measuring the magnitude of the second order harmonic waves. An inherent weakness of this method is the difficulty in distinguishing material nonlinearity from the nonlinearity of the measurement system. In this paper, we demonstrate the possibility of using collinear mixing waves to measure β. The wave mixing method is based on the interaction between two incident waves in a nonlinear medium. Under certain conditions, such interactions generate a third wave of different frequency. This generated third wave is also called resonant wave, because its amplitude is unbounded if the medium has no attenuation. Such resonant waves are less sensitive to the nonlinearity of the measurement system, and have the potential to identify the source location of the nonlinearity. In this work, we used a longitudinal wave and a shear wave as the incident waves. The resonant shear wave is measured experimentally on samples made of aluminum and steel, respectively. Numerical simulations of the tests were also performed using a finite difference method.
Acoustic wave-equation-based earthquake location
Tong, Ping; Yang, Dinghui; Liu, Qinya; Yang, Xu; Harris, Jerry
2016-04-01
We present a novel earthquake location method using acoustic wave-equation-based traveltime inversion. The linear relationship between the location perturbation (δt0, δxs) and the resulting traveltime residual δt of a particular seismic phase, represented by the traveltime sensitivity kernel K(t0, xs) with respect to the earthquake location (t0, xs), is theoretically derived based on the adjoint method. Traveltime sensitivity kernel K(t0, xs) is formulated as a convolution between the forward and adjoint wavefields, which are calculated by numerically solving two acoustic wave equations. The advantage of this newly derived traveltime kernel is that it not only takes into account the earthquake-receiver geometry but also accurately honours the complexity of the velocity model. The earthquake location is obtained by solving a regularized least-squares problem. In 3-D realistic applications, it is computationally expensive to conduct full wave simulations. Therefore, we propose a 2.5-D approach which assumes the forward and adjoint wave simulations within a 2-D vertical plane passing through the earthquake and receiver. Various synthetic examples show the accuracy of this acoustic wave-equation-based earthquake location method. The accuracy and efficiency of the 2.5-D approach for 3-D earthquake location are further verified by its application to the 2004 Big Bear earthquake in Southern California.
Extraordinary transmission of gigahertz surface acoustic waves
Mezil, Sylvain; Chonan, Kazuki; Otsuka, Paul H.; Tomoda, Motonobu; Matsuda, Osamu; Lee, Sam H.; Wright, Oliver B.
2016-09-01
Extraordinary transmission of waves, i.e. a transmission superior to the amount predicted by geometrical considerations of the aperture alone, has to date only been studied in the bulk. Here we present a new class of extraordinary transmission for waves confined in two dimensions to a flat surface. By means of acoustic numerical simulations in the gigahertz range, corresponding to acoustic wavelengths λ ~ 3–50 μm, we track the transmission of plane surface acoustic wave fronts between two silicon blocks joined by a deeply subwavelength bridge of variable length with or without an attached cavity. Several resonant modes of the structure, both one- and two-dimensional in nature, lead to extraordinary acoustic transmission, in this case with transmission efficiencies, i.e. intensity enhancements, up to ~23 and ~8 in the two respective cases. We show how the cavity shape and bridge size influence the extraordinary transmission efficiency. Applications include new metamaterials and subwavelength imaging.
Extraordinary transmission of gigahertz surface acoustic waves.
Mezil, Sylvain; Chonan, Kazuki; Otsuka, Paul H; Tomoda, Motonobu; Matsuda, Osamu; Lee, Sam H; Wright, Oliver B
2016-01-01
Extraordinary transmission of waves, i.e. a transmission superior to the amount predicted by geometrical considerations of the aperture alone, has to date only been studied in the bulk. Here we present a new class of extraordinary transmission for waves confined in two dimensions to a flat surface. By means of acoustic numerical simulations in the gigahertz range, corresponding to acoustic wavelengths λ ~ 3-50 μm, we track the transmission of plane surface acoustic wave fronts between two silicon blocks joined by a deeply subwavelength bridge of variable length with or without an attached cavity. Several resonant modes of the structure, both one- and two-dimensional in nature, lead to extraordinary acoustic transmission, in this case with transmission efficiencies, i.e. intensity enhancements, up to ~23 and ~8 in the two respective cases. We show how the cavity shape and bridge size influence the extraordinary transmission efficiency. Applications include new metamaterials and subwavelength imaging. PMID:27640998
Extraordinary transmission of gigahertz surface acoustic waves.
Mezil, Sylvain; Chonan, Kazuki; Otsuka, Paul H; Tomoda, Motonobu; Matsuda, Osamu; Lee, Sam H; Wright, Oliver B
2016-09-19
Extraordinary transmission of waves, i.e. a transmission superior to the amount predicted by geometrical considerations of the aperture alone, has to date only been studied in the bulk. Here we present a new class of extraordinary transmission for waves confined in two dimensions to a flat surface. By means of acoustic numerical simulations in the gigahertz range, corresponding to acoustic wavelengths λ ~ 3-50 μm, we track the transmission of plane surface acoustic wave fronts between two silicon blocks joined by a deeply subwavelength bridge of variable length with or without an attached cavity. Several resonant modes of the structure, both one- and two-dimensional in nature, lead to extraordinary acoustic transmission, in this case with transmission efficiencies, i.e. intensity enhancements, up to ~23 and ~8 in the two respective cases. We show how the cavity shape and bridge size influence the extraordinary transmission efficiency. Applications include new metamaterials and subwavelength imaging.
Extraordinary transmission of gigahertz surface acoustic waves
Mezil, Sylvain; Chonan, Kazuki; Otsuka, Paul H.; Tomoda, Motonobu; Matsuda, Osamu; Lee, Sam H.; Wright, Oliver B.
2016-01-01
Extraordinary transmission of waves, i.e. a transmission superior to the amount predicted by geometrical considerations of the aperture alone, has to date only been studied in the bulk. Here we present a new class of extraordinary transmission for waves confined in two dimensions to a flat surface. By means of acoustic numerical simulations in the gigahertz range, corresponding to acoustic wavelengths λ ~ 3–50 μm, we track the transmission of plane surface acoustic wave fronts between two silicon blocks joined by a deeply subwavelength bridge of variable length with or without an attached cavity. Several resonant modes of the structure, both one- and two-dimensional in nature, lead to extraordinary acoustic transmission, in this case with transmission efficiencies, i.e. intensity enhancements, up to ~23 and ~8 in the two respective cases. We show how the cavity shape and bridge size influence the extraordinary transmission efficiency. Applications include new metamaterials and subwavelength imaging. PMID:27640998
Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator
Polzikova, N. I.; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P.
2016-05-01
We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW) resonator (HBAR) formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE) this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.
Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator
Directory of Open Access Journals (Sweden)
N. I. Polzikova
2016-05-01
Full Text Available We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW resonator (HBAR formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.
Modified KdV equation for solitary Rossby waves with β effect in barotropic fluids
Institute of Scientific and Technical Information of China (English)
Song Jian; Yang Lian-Gui
2009-01-01
This paper uses the weakly nonlinear method and perturbation method to deal with the quasi-geostrophic vorticity equation, and the modified Korteweg-de Vries(mKdV) equations describing the evolution of the amplitude of solitary Rossby waves as the change of Rossby parameter β(y) with latitude y is obtained.
A Comparative Study on Three Different Transducers for the Measurement of Nonlinear Solitary Waves
Directory of Open Access Journals (Sweden)
Piervincenzo Rizzo
2013-01-01
Full Text Available In the last decade there has been an increasing interest in the use of highly- and weakly- nonlinear solitary waves in engineering and physics. Nonlinear solitary waves can form and travel in nonlinear systems such as one-dimensional chains of particles, where they are conventionally generated by the mechanical impact of a striker and are measured either by using thin transducers embedded in between two half-particles or by a force sensor placed at the chain’s base. These waves have a constant spatial wavelength and their speed, amplitude, and duration can be tuned by modifying the particles’ material or size, or the velocity of the striker. In this paper we propose two alternative sensing configurations for the measurements of solitary waves propagating in a chain of spherical particles. One configuration uses piezo rods placed in the chain while the other exploits the magnetostrictive property of ferromagnetic materials. The accuracy of these two sensing systems on the measurement of the solitary wave’s characteristics is assessed by comparing experimental data to the numerical prediction of a discrete particle model and to the experimental measurements obtained by means of a conventional transducer. The results show very good agreement and the advantages and limitations of the new sensors are discussed.
Kinetic, potential and surface tension energies of solitary waves in deep water
Hur, Vera Mikyoung
2015-01-01
We present an exact relation among the kinetic, potential and surface tension energies of a solitary wave in deep water in all dimensions. We deduce its non-existence in the absence of the effects of surface tension, provided that gravity acts in a direction opposite to what is physically realistic.
Kinetic, potential and surface tension energies of solitary waves in deep water
International Nuclear Information System (INIS)
We present an exact relation among the kinetic, potential and surface tension energies of a solitary wave in deep water in all dimensions. We deduce its non-existence in the absence of the effects of surface tension, provided that gravity acts in a direction opposite to what is physically realistic. (fast track communication)
STABILITY AND INSTABILITY OF SOLITARY WAVES FOR ABSTRACT COMPLEX HAMILTONIAN SYSTEM
Institute of Scientific and Technical Information of China (English)
Zhao Ye
2005-01-01
This paper is concerned with the orbital stability and orbital instability of solitary waves for some complex Hamiltonian systems in abstract form. Under some assumptions on the spectra of the related operator and the decaying estimates of the semigroup, the sufficient conditions on orbital stability and instability are obtained.
THE EXACT SOLITARY WAVE SOLUTIONS FOR THE KLEIN-GORDON-SCHR(O)DINGER EQUATIONS
Institute of Scientific and Technical Information of China (English)
夏静娜; 韩淑霞; 王明亮
2002-01-01
The solitary wave solutions for the Klein-Gordon-Schrodinger Equations were obtained by using the homogeaeous balance principle. The form of the solutions is more generalized than the result that has been proved by pure theoretical and qualitative method in literature;namely, the form of solutions in literature is a particular case of result of the present paper.
Smyrnakis, J.; Magiropoulos, M.; Kavoulakis, G. M.; Jackson, A. D.
2013-01-01
We derive solitary-wave solutions within the mean-field approximation in quasi-one-dimensional binary mixtures of Bose-Einstein condensates under periodic boundary conditions, for the case of an effective repulsive interatomic interaction. The particular gray-bright solutions that give the global energy minima are determined. Their characteristics and the associated dispersion relation are derived.
Is DNA a nonlinear dynamical system where solitary conformational waves are possible?
Indian Academy of Sciences (India)
Ludmila V Yakushevich
2001-09-01
DNA is considered as a nonlinear dynamical system in which solitary conformational waves can be excited. The history of the approach, the main results, and arguments in favour and against are presented. Perspectives are discussed pertaining to studies of DNA’s nonlinear properties.
Solitary waves in Galilean covariant Fermi field theories with self-interaction
Saradzhev, Fuad M
2014-01-01
The generalized Levy-Leblond equation for a $(3+1)$-dimensional self-interacting Fermi field is considered. Spin up solitary wave solutions with space oscillations in the $x^3$-coordinate are constructed. The solutions are shown to accumulate non-equal amounts of inertial and rest masses.
The homotopic mapping solution for the solitary wave for a generalized nonlinear evolution equation
Institute of Scientific and Technical Information of China (English)
Mo Jia-Qi; Lin Su-Rong
2009-01-01
This paper studies a generalized nonlinear evolution equation. Using the homotopic mapping method,it constructs a corresponding homotopic mapping transform. Selecting a suitable initial approximation and using homotopic mapping,it obtains an approximate solution with an arbitrary degree of accuracy for the solitary wave. From the approximate solution obtained by using the homotopic mapping method,it possesses a good accuracy.
Acoustic-gravity waves, theory and application
Kadri, Usama; Farrell, William E.; Munk, Walter
2015-04-01
Acoustic-gravity waves (AGW) propagate in the ocean under the influence of both the compressibility of sea water and the restoring force of gravity. The gravity dependence vanishes if the wave vector is normal to the ocean surface, but becomes increasingly important as the wave vector acquires a horizontal tilt. They are excited by many sources, including non-linear surface wave interactions, disturbances of the ocean bottom (submarine earthquakes and landslides) and underwater explosions. In this introductory lecture on acoustic-gravity waves, we describe their properties, and their relation to organ pipe modes, to microseisms, and to deep ocean signatures by short surface waves. We discuss the generation of AGW by underwater earthquakes; knowledge of their behaviour with water depth can be applied for the early detection of tsunamis. We also discuss their generation by the non-linear interaction of surface gravity waves, which explains the major role they play in transforming energy from the ocean surface to the crust, as part of the microseisms phenomenon. Finally, they contribute to horizontal water transport at depth, which might affect benthic life.
Absorption of surface acoustic waves by graphene
Directory of Open Access Journals (Sweden)
S. H. Zhang
2011-06-01
Full Text Available We present a theoretical study on interactions of electrons in graphene with surface acoustic waves (SAWs. We find that owing to momentum and energy conservation laws, the electronic transition accompanied by the SAW absorption cannot be achieved via inter-band transition channels in graphene. For graphene, strong absorption of SAWs can be observed in a wide frequency range up to terahertz at room temperature. The intensity of SAW absorption by graphene depends strongly on temperature and can be adjusted by changing the carrier density. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as frequency-tunable SAW devices.
On solitary waves. Part 2 A unified perturbation theory for higher-order waves
Institute of Scientific and Technical Information of China (English)
Theodore Yaotsu Wu; Xinlong Wang; Wendong Qu
2005-01-01
A unified perturbation theory is developed here for calculating solitary waves of all heights by series expansion of base flow variables in powers of a small base parameter to eighteenth order for the one-parameter family of solutions in exact form, with all the coefficients determined in rational numbers. Comparative studies are pursued to investigate the effects due to changes of base parameters on (i) the accuracy of the theoretically predicted wave properties and (ii) the rate of convergence of perturbation expansion. Two important results are found by comparisons between the theoretical predictions based on a set of parameters separately adopted for expansion in turn. First, the accuracy and the convergence of the perturbation expansions, appraised versus the exact solution provided by an earlier paper [1] as the standard reference, are found to depend, quite sensitively, on changes in base parameter. The resulting variations in the solution are physically displayed in various wave properties with differences found dependent on which property (e.g.the wave amplitude, speed, its profile, excess mass, momentum, and energy), on what range in value of the base, and on the rank of the order n in the expansion being addressed.Secondly, regarding convergence, the present perturbation series is found definitely asymptotic in nature, with the relative error δ (n) (the relative mean-square difference between successive orders n of wave elevations) reaching a minimum,δm, at a specific order, n = nm, both depending on the base adopted, e.g. n = 11-12 based on parameter α (wave amplitude), nm,β = 15 onβ (amplitude-speed square ratio),and nm.∈ = 17 on ∈ ( wave number squared). The asymptotic range is brought to completion by the highest order of n = 18 reached in this work.
Relativistic breather-like solitary waves with linear polarization in cold plasmas
Sánchez-Arriaga, G; Saxena, V; Kourakis, I
2014-01-01
Linearly polarized solitary waves, arising from the interaction of an intense laser pulse with a plasma, are investigated. New localized structures, in the form of exact, nonlinear solutions of the one-dimensional Maxwell-fluid model for a cold plasma with fixed ions are presented. Unlike stationary circularly polarized solitary waves, the linear polarization gives rise to a breather-like behavior and a periodic exchange of electromagnetic energy and electron kinetic energy at twice the frequency of the wave. A numerical method based on a finite-differences scheme allows to compute a branch of solutions within the frequency range $\\Omega_{min}<\\Omega<\\omega_{pe}$, where $\\omega_{pe}$ and $\\Omega_{min}$ are the electron plasma frequency and the frequency value for which the plasma density vanishes locally, respectively. A detailed description of the spatio-temporal structure of the waves and their main properties as a function of $\\Omega$ are presented. Small amplitude oscillations appearing in the tail ...
Acoustic Remote Sensing of Rogue Waves
Parsons, Wade; Kadri, Usama
2016-04-01
We propose an early warning system for approaching rogue waves using the remote sensing of acoustic-gravity waves (AGWs) - progressive sound waves that propagate at the speed of sound in the ocean. It is believed that AGWs are generated during the formation of rogue waves, carrying information on the rogue waves at near the speed of sound, i.e. much faster than the rogue wave. The capability of identifying those special sound waves would enable detecting rogue waves most efficiently. A lot of promising work has been reported on AGWs in the last few years, part of which in the context of remote sensing as an early detection of tsunami. However, to our knowledge none of the work addresses the problem of rogue waves directly. Although there remains some uncertainty as to the proper definition of a rogue wave, there is little doubt that they exist and no one can dispute the potential destructive power of rogue waves. An early warning system for such extreme waves would become a demanding safety technology. A closed form expression was developed for the pressure induced by an impulsive source at the free surface (the Green's function) from which the solution for more general sources can be developed. In particular, we used the model of the Draupner Wave of January 1st, 1995 as a source and calculated the induced AGW signature. In particular we studied the AGW signature associated with a special feature of this wave, and characteristic of rogue waves, of the absence of any local set-down beneath the main crest and the presence of a large local set-up.
NEAR-FIELD ACOUSTIC HOLOGRAPHY FOR SEMI-FREE ACOUSTIC FIELD BASED ON WAVE SUPERPOSITION APPROACH
Institute of Scientific and Technical Information of China (English)
LI Weibing; CHEN Jian; YU Fei; CHEN Xinzhao
2006-01-01
In the semi-free acoustic field, the actual acoustic pressure at any point is composed of two parts: The direct acoustic pressure and the reflected acoustic pressure. The general acoustic holographic theories and algorithms request that there is only the direct acoustic pressure contained in the pressure at any point on the hologram surface, consequently, they cannot be used to reconstruct acoustic source and predict acoustic field directly. To take the reflected pressure into consideration, near-field acoustic holography for semi-free acoustic field based on wave superposition approach is proposed to realize the holographic reconstruction and prediction of the semi-free acoustic field, and the wave superposition approach is adopted as a holographic transform algorithm. The proposed theory and algorithm are realized and verified with a numerical example,and the drawbacks of the general theories and algorithms in the holographic reconstruction and prediction of the semi-free acoustic field are also demonstrated by this numerical example.
On the Dynamics of Two-Dimensional Capillary-Gravity Solitary Waves with a Linear Shear Current
Directory of Open Access Journals (Sweden)
Dali Guo
2014-01-01
Full Text Available The numerical study of the dynamics of two-dimensional capillary-gravity solitary waves on a linear shear current is presented in this paper. The numerical method is based on the time-dependent conformal mapping. The stability of different kinds of solitary waves is considered. Both depression wave and large amplitude elevation wave are found to be stable, while small amplitude elevation wave is unstable to the small perturbation, and it finally evolves to be a depression wave with tails, which is similar to the irrotational capillary-gravity waves.
Institute of Scientific and Technical Information of China (English)
刘长根; 陶建华
2004-01-01
A vertical 2-D numerical wave model was developed based on unsteady Reynolds equations. In this model, the k-epsilon models were used to close the Reynolds equations, and volume of fluid(VOF) method was used to reconstruct the free surface. The model was verified by experimental data. Then the model was used to simulate solitary wave interaction with submerged, alternative submerged and emerged semi-circular breakwaters. The process of velocity field, pressure field and the wave surface near the breakwaters was obtained. It is found that when the semi-circular breakwater is submerged, a large vortex will be generated at the bottom of the lee side wall of the breakwater; when the still water depth is equal to the radius of the semi-circular breakwater, a pair of large vortices will be generated near the shoreward wall of the semi-circular breakwater due to wave impacting, but the velocity near the bottom of the lee side wall of the breakwater is always relatively small. When the semi-circular breakwater is emerged, and solitary wave cannot overtop it, the solitary wave surface will run up and down secondarily during reflecting from the breakwater. It can be further used to estate the diffusing and transportation of the contamination and transportation of suspended sediment.
Wave-Induced Pressure Under an Internal Solitary Wave and Its Impact at the Bed
Rivera, Gustavo; Diamesis, Peter; Jenkins, James; Berzi, Diego
2015-11-01
The bottom boundary layer (BBL) under a mode-1 internal solitary wave (ISW) of depression propagating against an oncoming model barotropic current is examined using 2-D direct numerical simulation based on a spectral multidomain penalty method model. Particular emphasis is placed on the diffusion into the bed of the pressure field driven by the wake and any near-bed instabilities produced under specific conditions. To this end, a spectral nodal Galerkin approach is used for solving the diffusion equation for the wave-induced pressure. At sufficiently high ISW amplitude, the BBL undergoes a global instability which produces intermittent vortex shedding from within the separation bubble in the lee of the wave. The interplay between the bottom shear stress field and pressure perturbations during vortex ejection events and the subsequent evolution of the vortices is examined. The potential for bed failure upon the passage of the ISW trough and implications for resuspension of bottom particulate matter are both discussed in the context of specific sediment transport models.
Yang, Jianke
2012-03-01
Saddle-node bifurcations arise frequently in solitary waves of diverse physical systems. Previously it was believed that solitary waves always undergo stability switching at saddle-node bifurcations, just as in finite-dimensional dynamical systems. Here we show that this is not true. For a large class of generalized nonlinear Schrödinger equations with real or complex potentials, we prove that stability of solitary waves does not switch at saddle-node bifurcations. This analytical result is confirmed by numerical examples where both soliton branches are stable at saddle-node bifurcations.
Holographic imaging of surface acoustic waves
Bruno, Francois; Royer, Daniel; Atlan, Michael
2014-01-01
We report on an experimental demonstration of surface acoustic waves monitoring on a thin metal plate with heterodyne optical holography. Narrowband imaging of local optical pathlength modulation is achieved with a frequency-tunable time-averaged laser Doppler holographic imaging scheme on a sensor array, at video-rate. This method enables robust and quantitative mapping of out-of-plane vibrations of nanometric amplitudes at radiofrequencies.
Nonlinear ion acoustic waves scattered by vortexes
Ohno, Yuji; Yoshida, Zensho
2016-09-01
The Kadomtsev-Petviashvili (KP) hierarchy is the archetype of infinite-dimensional integrable systems, which describes nonlinear ion acoustic waves in two-dimensional space. This remarkably ordered system resides on a singular submanifold (leaf) embedded in a larger phase space of more general ion acoustic waves (low-frequency electrostatic perturbations). The KP hierarchy is characterized not only by small amplitudes but also by irrotational (zero-vorticity) velocity fields. In fact, the KP equation is derived by eliminating vorticity at every order of the reductive perturbation. Here, we modify the scaling of the velocity field so as to introduce a vortex term. The newly derived system of equations consists of a generalized three-dimensional KP equation and a two-dimensional vortex equation. The former describes 'scattering' of vortex-free waves by ambient vortexes that are determined by the latter. We say that the vortexes are 'ambient' because they do not receive reciprocal reactions from the waves (i.e., the vortex equation is independent of the wave fields). This model describes a minimal departure from the integrable KP system. By the Painlevé test, we delineate how the vorticity term violates integrability, bringing about an essential three-dimensionality to the solutions. By numerical simulation, we show how the solitons are scattered by vortexes and become chaotic.
Algebraic method for constructing singular steady solitary waves: a case study
Clamond, Didier; Dutykh, Denys; Galligo, André
2016-07-01
This article describes the use of algebraic methods in a phase plane analysis of ordinary differential equations. The method is illustrated by the study of capillary-gravity steady surface waves propagating in shallow water. We consider the (fully nonlinear, weakly dispersive) Serre-Green-Naghdi equation with surface tension, because it provides a tractable model that, at the same time, is not too simple, so interest in the method can be emphasized. In particular, we analyse a special class of solutions, the solitary waves, which play an important role in many fields of physics. In capillary-gravity regime, there are two kinds of localized infinitely smooth travelling wave solutions-solitary waves of elevation and of depression. However, if we allow the solitary waves to have an angular point, then the `zoology' of solutions becomes much richer, and the main goal of this study is to provide a complete classification of such singular localized solutions using the methods of the effective algebraic geometry.
Algebraic method for constructing singular steady solitary waves: A case study
Clamond, Didier; Galligo, André
2016-01-01
This article describes the use of algebraic methods in a phase plane analysis of ordinary differential equations. The method is illustrated by the study of capillary-gravity steady surface waves propagating in shallow water. We consider the (fully nonlinear, weakly dispersive) Serre-Green-Naghdi equations with surface tension, because it provides a tractable model that, in the same time, is not too simple so the interest of the method can be emphasised. In particular, we analyse a special class of solutions, the solitary waves, which play an important role in many fields of Physics. In capillary-gravity regime, there are two kinds of localised infinitely smooth travelling wave solutions -- solitary waves of elevation and of depression. However, if we allow the solitary waves to have an angular point, the "zoology" of solutions becomes much richer and the main goal of this study is to provide a complete classification of such singular localised solutions using the methods of the effective Algebraic Geometry.
Non-Linear Excitation of Ion Acoustic Waves
DEFF Research Database (Denmark)
Michelsen, Poul; Hirsfield, J. L.
1974-01-01
The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation.......The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation....
Miscellaneous Rotating Solitary Waves to a Coupled Dispersionless System
International Nuclear Information System (INIS)
We investigate the soliton structure of a coupled dispersionless system describing a current-conducting string with infinite length within a magnetic field. Thus, following Hirota's method, we unwrap three typical localized waves with nonzero angular momentum depending strongly upon their angular velocities. Illustrating the soliton behavior of these waves, we focus our interests on breather-like waves and depict the elastic scattering amongst such waves
Institute of Scientific and Technical Information of China (English)
FAN Zhisong; ZHANG Yuanling; SONG Mei
2008-01-01
A new model developed from the full-spectrum model of Lyzenga and Bennett (1988) is built up by us preliminarily through considering the impact of the ocean surface mixed layer turbulence on SAR remote sensing of internal solitary waves. In the partial differential equation of the action spectral density of the surface gravity-capillary waves the source function representing the contribution of the turbulence is added besides the usual source function representing the contribution of the wind. The source function is determined by applying the k-εmodel and adopting the Nasmyth spectrum of oceanic turbulence ( Nasmyth, 1970 ; Oakey, 1982; Fan, 2002 ) on the basis of the previous simulation results of internal tide transformation obtained in the companion paper ( Fan et al. ,2008 ). Either under relatively high wind speed, or under low wind speed, our model predicts significant large modulations of radar backscatter at all three bands ( L, C and X bands) for both VV and HH polarization. These results prove that considering the impact of ocean surface mixed layer turbulence on SAR remote sensing of internal solitary waves is reasonable and appropriate for settlement of the well-known problem of contemporary radar imaging models.
Nonlinear propagation of ion-acoustic waves in a degenerate dense plasma
Indian Academy of Sciences (India)
M M Masud; A A Mamun
2013-07-01
Nonlinear propagation of ion-acoustic (IA) waves in a degenerate dense plasma (with all the constituents being degenerate, for both the non-relativistic or ultrarelativistic cases) have been investigated by the reductive perturbation method. The linear dispersion relation and Korteweg de Vries (KdV) equation have been derived, and the numerical solutions of KdV equation have been analysed to identify the basic features of electrostatic solitary structures that may form in such a degenerate dense plasma. The implications of our results in compact astrophysical objects, particularly, in white dwarfs and neutron stars, have been briefly discussed.
Coherent structures in wave boundary layers. Part 2. Solitary motion
DEFF Research Database (Denmark)
Sumer, B. Mutlu; Jensen, Palle Martin; Sørensen, Lone B.;
2010-01-01
in an oscillating water tunnel. Two kinds of measurements were made: bed shear stress measurements and velocity measurements. The experiments show that the solitary-motion boundary layer experiences three kinds of flow regimes as the Reynolds number is increased: (i) laminar regime; (ii) laminar regime where...... the boundary-layer flow experiences a regular array of vortex tubes near the bed over a short period of time during the deceleration stage; and (iii) transitional regime characterized with turbulent spots, revealed by single/multiple, or, sometimes, quite dense spikes in the bed shear stress traces....... Supplementary synchronized flow visualization tests confirmed the presence of the previously mentioned flow features. Information related to flow resistance are also given in the paper....
Nonlinear ion acoustic waves scattered by vortexes
Ohno, Yuji
2015-01-01
The Kadomtsev--Petviashvili (KP) hierarchy is the archetype of infinite-dimensional integrable systems, which describes nonlinear ion acoustic waves in two-dimensional space. This remarkably ordered system resides on a singular submanifold (leaf) embedded in a larger phase space of more general ion acoustic waves (low-frequency electrostatic perturbations). The KP hierarchy is characterized not only by small amplitudes but also by irrotational (zero-vorticity) velocity fields. In fact, the KP equation is derived by eliminating vorticity at every order of the reductive perturbation. Here we modify the scaling of the velocity field so as to introduce a vortex term. The newly derived system of equations consists of a generalized three-dimensional KP equation and a two-dimensional vortex equation. The former describes `scattering' of vortex-free waves by ambient vortexes that are determined by the latter. We say that the vortexes are `ambient' because they do not receive reciprocal reactions from the waves (i.e.,...
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Uday Narayan, E-mail: unghosh1@rediffmail.com; Chatterjee, Prasanta; Roychoudhury, Rajkumar [Department of Mathematics, Siksha Bhavana, Visva Bharati, Santiniketan 731235 (India)
2015-07-15
Recently Gun Li et al. discussed “Effects of damping solitary wave in a viscosity bounded plasma” [Phys. Plasmas 21, 022118 (2014)]. The paper contains some serious errors which have been pointed out in this Comment.
Ship-induced solitary Riemann waves of depression in Venice Lagoon
Energy Technology Data Exchange (ETDEWEB)
Parnell, Kevin E. [College of Marine and Environmental Sciences and Centre for Tropical Environmental and Sustainability Sciences, James Cook University, Queensland 4811 (Australia); Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Soomere, Tarmo, E-mail: soomere@cs.ioc.ee [Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn (Estonia); Zaggia, Luca [Institute of Marine Sciences, National Research Council, Castello 2737/F, 30122 Venice (Italy); Rodin, Artem [Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Lorenzetti, Giuliano [Institute of Marine Sciences, National Research Council, Castello 2737/F, 30122 Venice (Italy); Rapaglia, John [Sacred Heart University Department of Biology, 5151 Park Avenue, Fairfield, CT 06825 (United States); Scarpa, Gian Marco [Università Ca' Foscari, Dorsoduro 3246, 30123 Venice (Italy)
2015-03-06
We demonstrate that ships of moderate size, sailing at low depth Froude numbers (0.37–0.5) in a navigation channel surrounded by shallow banks, produce depressions with depths up to 2.5 m. These depressions (Bernoulli wakes) propagate as long-living strongly nonlinear solitary Riemann waves of depression substantial distances into Venice Lagoon. They gradually become strongly asymmetric with the rear of the depression becoming extremely steep, similar to a bore. As they are dynamically similar, air pressure fluctuations moving over variable-depth coastal areas could generate meteorological tsunamis with a leading depression wave followed by a devastating bore-like feature. - Highlights: • Unprecedently deep long-living ship-induced waves of depression detected. • Such waves are generated in channels with side banks under low Froude numbers. • The propagation of these waves is replicated using Riemann waves. • Long-living waves of depression form bore-like features at rear slope.
Ship-induced solitary Riemann waves of depression in Venice Lagoon
International Nuclear Information System (INIS)
We demonstrate that ships of moderate size, sailing at low depth Froude numbers (0.37–0.5) in a navigation channel surrounded by shallow banks, produce depressions with depths up to 2.5 m. These depressions (Bernoulli wakes) propagate as long-living strongly nonlinear solitary Riemann waves of depression substantial distances into Venice Lagoon. They gradually become strongly asymmetric with the rear of the depression becoming extremely steep, similar to a bore. As they are dynamically similar, air pressure fluctuations moving over variable-depth coastal areas could generate meteorological tsunamis with a leading depression wave followed by a devastating bore-like feature. - Highlights: • Unprecedently deep long-living ship-induced waves of depression detected. • Such waves are generated in channels with side banks under low Froude numbers. • The propagation of these waves is replicated using Riemann waves. • Long-living waves of depression form bore-like features at rear slope
On the generation and evolution of internal solitary waves in the southern Red Sea
Guo, Daquan
2015-04-01
Satellite observations recently revealed the existence of trains of internal solitary waves in the southern Red Sea between 16.0°N and 16.5°N, propagating from the centre of the domain toward the continental shelf [Da silva et al., 2012]. Given the relatively weak tidal velocity in this area and their generation in the central of the domain, Da Silva suggested three possible mechanisms behind the generation of the waves, namely Resonance and disintegration of interfacial tides, Generation of interfacial tides by impinging, remotely generated internal tidal beams and for geometrically focused and amplified internal tidal beams. Tide analysis based on tide stations data and barotropic tide model in the Red Sea shows that tide is indeed very weak in the centre part of the Red Sea, but it is relatively strong in the northern and southern parts (reaching up to 66 cm/s). Together with extreme steep slopes along the deep trench, it provides favourable conditions for the generation of internal solitary in the southern Red Sea. To investigate the generation mechanisms and study the evolution of the internal waves in the off-shelf region of the southern Red Sea we have implemented a 2-D, high-resolution and non-hydrostatic configuration of the MIT general circulation model (MITgcm). Our simulations reproduce well that the generation process of the internal solitary waves. Analysis of the model\\'s output suggests that the interaction between the topography and tidal flow with the nonlinear effect is the main mechanism behind the generation of the internal solitary waves. Sensitivity experiments suggest that neither tidal beam nor the resonance effect of the topography is important factor in this process.
Broadband Acoustic Cloak for Ultrasound Waves
Zhang, Shu; Fang, Nicholas
2010-01-01
Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Due to the non-resonant nature of the building elements, this low loss (~6dB/m) cylindrical cloak exhibits excellent invisibility over a broad frequency range from 52 to 64 kHz in the measurements. The low visibility of the cloaked object for underwater ultrasound shed a light on the fundamental understanding of ma...
Measuring Acoustic Wave Transit Time in Furnace Based on Active Acoustic Source Signal
Institute of Scientific and Technical Information of China (English)
Zhen Luo; Feng Tian; Xiao-Ping Sun
2007-01-01
Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new method for measuring transit time of acoustic wave based on active acoustic source signal is proposed in this paper, which includes the followings: the time when the acoustic source signal arrives at the two sensors is measured first; then, the difference of two arriving time arguments is computed, thereby we get the transit time of the acoustic wave between two sensors installed on the two sides of the furnace. Avoiding the restriction on acoustic source signal and background noise, the new method can get the transit time of acoustic wave with higher precision and stronger ability of resisting noise interference.
Numerical modeling on the interaction of internal solitary wave with slope-shelf and modal analysis
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
On the basis of a nonhydrostatic numerical model, the interaction of internal solitary wave with slope-shelf was studied. The breaking and polarity transformation were analyzed. A "kink" structure, due to shoaling topography and higher nonlinear effect, was found to be generated by the leading wave before breaking. Coherent vortex shedding behind the leading wave was presented. The evolution characteristics of the modal structure were analyzed based on the empirical orthogonal function method. The modal structure was complicated due to the effect of the variable topography, especially when breaking occurred. In the performed experiments, the contributions to the total variance from higher mode jumped from no more than 20% to over 40%.
Solitary Shock Waves near Phase Transition in Lipid Interfaces and Nerves
Shrivastava, Shamit; Schneider, Matthias
2014-01-01
This study shows that the stability of solitary waves excited in a lipid monolayer near a phase boundary requires positive curvature of the adiabats, a known necessary condition in shock compression science. It is further shown that the condition results in a threshold for excitation, saturation of the wave amplitude and the splitting of the wave at the phase boundaries. The observed phenomenon has far reaching consequences for dynamic biological processes and is hypothesized to be closely tied to the existence of both, the threshold and thermodynamic blockage of nerve pulse propagation.
TWO-DIMENSIONAL ALGEBRAIC SOLITARY WAVE AND ITS VERTICAL STRUCTURE IN STRATIFIED FLUID
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
The algebraic solitary wave and its associated eigenvalue problem in a deep stratified fluid with a free surface and a shallow upper layer were studied. And its vertical structure was examined. An exact solution for the derived 2D Benjamin-Ono equation was obtained, and physical explanation was given with the corresponding dispersion relation. As a special case, the vertical structure of the weakly nonlinear internal wave for the Holmboe density distribution was numerically investigated, and the propagating mechanism of the internal wave was studied by using the ray theory.
Stable solitary waves in Super dense plasmas at external magnetic fields
Ghaani, Azam; Sarbishaei, Mohsen
2014-01-01
Propagation of localized waves in a Fermi-Dirac distributed super dense matter at the presence of strong external magnetic fields is studied using the reductive perturbation method. Previous works indicate that localized waves break down in unmagnetized super dense hadronic matter. We have shown that stable solitons can be created in such non-relativistic fluids in the presence of an external magnetic field. Such solitary waves are governed by the Zakharov-Kuznetsov (ZK) equation. Properties of solitonic solutions are studied in media with different values of back ground mass density and strength of magnetic field.
Gravity solitary waves with polynomial decay to exponentially small ripples at infinity
Lombardi, E; Iooss, Gérard
2003-01-01
International audience In this paper, we study the travelling gravity waves of velocity c in a system of two layers of perfect fluids, the bottom one being infinitely deep, the upper one having a finite thickness h. We assume that the flow is potential, and the dimensionless parameters are the ratio between densities ρ = ρ2/ρ1 and λ=gh/c^2. For ε = 1 − λ(1 − ρ) near 0 + , the existence of periodic travelling waves of arbitrary small amplitude and the existence of generalized solitary waves...
Indian Academy of Sciences (India)
BHARDWAJ S B; SINGH RAM MEHAR; SHARMA KUSHAL; MISHRA S C
2016-06-01
Attempts have been made to explore the exact periodic and solitary wave solutions of nonlinear reaction diffusion (RD) equation involving cubic–quintic nonlinearity along with timedependent convection coefficients. Effect of varying model coefficients on the physical parameters of solitary wave solutions is demonstrated. Depending upon the parametric condition, the periodic,double-kink, bell and antikink-type solutions for cubic–quintic nonlinear reaction-diffusion equation are extracted. Such solutions can be used to explain various biological and physical phenomena.
Simulating acoustic waves in spotted stars
Papini, Emanuele; Gizon, Laurent; Hanasoge, Shravan M
2015-01-01
Acoustic modes of oscillation are affected by stellar activity, however it is unclear how starspots contribute to these changes. Here we investigate the non-magnetic effects of starspots on global modes with angular degree $\\ell \\leq 2$ in highly active stars, and characterize the spot seismic signature on synthetic light curves. We perform 3D time-domain simulations of linear acoustic waves to study their interaction with a model starspot. We model the spot as a 3D change in the sound speed stratification with respect to a convectively stable stellar background, built from solar Model S. We perform a parametric study by considering different depths and perturbation amplitudes. Exact numerical simulations allow investigation of the wavefield-spot interaction beyond first order perturbation theory. The interaction of the axisymmetric modes with the starspot is strongly nonlinear. As mode frequency increases, the frequency shifts for radial modes exceed the value predicted by linear theory, while the shifts for...
Yang, Jianke
2012-01-01
Linear stability of both sign-definite (positive) and sign-indefinite solitary waves near pitchfork bifurcations is analyzed for the generalized nonlinear Schroedinger equations with arbitrary forms of nonlinearity and external potentials in arbitrary spatial dimensions. Bifurcations of linear-stability eigenvalues associated with pitchfork bifurcations are analytically calculated. It is shown that the smooth solution branch switches stability at the bifurcation point. In addition, the two bifurcated solution branches and the smooth branch have the opposite (same) stability when their power slopes have the same (opposite) sign. One unusual feature on the stability of these pitchfork bifurcations is that the smooth and bifurcated solution branches can be both stable or both unstable, which contrasts such bifurcations in finite-dimensional dynamical systems where the smooth and bifurcated branches generally have opposite stability. For the special case of positive solitary waves, stronger and more explicit stab...
Evidence for 2D Solitary Sound Waves in a Lipid Controlled Interface and its Biological Implications
Shrivastava, Shamit
2014-01-01
Biological membranes by virtue of their elastic properties should be capable of propagating localized perturbations analogous to sound waves. However, the existence and the possible role of such waves in communication in biology remains unexplored. Here we report the first observations of 2D solitary elastic pulses in lipid interfaces, excited mechanically and detected by FRET. We demonstrate that the nonlinearity near a maximum in the susceptibility of the lipid monolayer results in solitary pulses that also have a threshold for excitation. These experiments clearly demonstrate that the state of the interface regulates the propagation of pulses both qualitatively and quantitatively. We elaborate on the striking similarity of the observed phenomenon to nerve pulse propagation and a thermodynamic basis of cell signaling in general.
Development of internal solitary waves in various thermocline regimes - a multi-modal approach
Directory of Open Access Journals (Sweden)
T. Gerkema
2003-01-01
Full Text Available A numerical analysis is made on the appearance of oceanic internal solitary waves in a multi-modal setting. This is done for observed profiles of stratification from the Sulu Sea and the Bay of Biscay, in which thermocline motion is dominated by the first and third mode, respectively. The results show that persistent solitary waves occur only in the former case, in accordance with the observations. In the Bay of Biscay much energy is transferred from the third mode to lower modes, implying that a uni-modal approach would not have been appropriate. To elaborate on these results in a systematic way, a simple model for the stratification is used; an interpretation is given in terms of regimes of thermocline strength.
International Nuclear Information System (INIS)
Nonparaxial and nonlinear propagation of a short intense laser beam in a parabolic plasma channel is analyzed by means of the variational method and nonlinear dynamics. The beam propagation properties are classified by five kinds of behaviors. In particularly, the electromagnetic solitary wave for finite pulse laser is found beside the other four propagation cases including beam periodically oscillating with defocussing and focusing amplitude, constant spot size, beam catastrophic focusing. It is also found that the laser pulse can be allowed to propagate in the plasma channel only when a certain relation for laser parameters and plasma channel parameters is satisfied. For the solitary wave, it may provide an effective way to obtain ultra-short laser pulse.
Classification of solitary wave bifurcations in generalized nonlinear Schr\\"odinger equations
Yang, Jianke
2012-01-01
Bifurcations of solitary waves are classified for the generalized nonlinear Schr\\"odinger equations with arbitrary nonlinearities and external potentials in arbitrary spatial dimensions. Analytical conditions are derived for three major types of solitary wave bifurcations, namely saddle-node bifurcations, pitchfork bifurcations and transcritical bifurcations. Shapes of power diagrams near these bifurcations are also obtained. It is shown that for pitchfork and transcritical bifurcations, their power diagrams look differently from their familiar solution-bifurcation diagrams. Numerical examples for these three types of bifurcations are given as well. Of these numerical examples, one shows a transcritical bifurcation, which is the first report of transcritical bifurcations in the generalized nonlinear Schr\\"odinger equations. Another shows a power loop phenomenon which contains several saddle-node bifurcations, and a third example shows double pitchfork bifurcations. These numerical examples are in good agreeme...
Solitary waves of α-helix propagation in media with arbitrary inhomogeneities
Mvogo, Alain; Ben-Bolie, Germain Hubert; Kofané, Timoléon Crépin
2013-05-01
We study the dynamics of solitary waves in α-helical proteins going beyond the standard nearest-neighbour interaction by taking into account influence long-range dipole-dipole interactions of the Kac-Baker type. By means of the coherent state representation of operators, the model Hamiltonian is transformed into a pair of classical lattice equations, which is further reduced to a sole nonlinear Schrödinger (NLS) equation using the continuum approximation of which the dispersive coefficient depends on the long-range interactions (LRI) parameter. It comes out from our results that the bright-like solitons, solitary waves which govern the energy transfer in α-helix, are deeply influenced by the LRI. At the end, we transform the NLS equation for more currently-important inhomogeneous NLS models in media with inhomogeneities. Application of this transformation to two example models is illustrated and soliton-like solutions are also graphically discussed.
Acoustic clouds: standing sound waves around a black hole analogue
Benone, Carolina L; Herdeiro, Carlos; Radu, Eugen
2014-01-01
Under certain conditions sound waves in fluids experience an acoustic horizon with analogue properties to those of a black hole event horizon. In particular, a draining bathtub-like model can give rise to a rotating acoustic horizon and hence a rotating black hole (acoustic) analogue. We show that sound waves, when enclosed in a cylindrical cavity, can form stationary waves around such rotating acoustic black holes. These acoustic perturbations display similar properties to the scalar clouds that have been studied around Kerr and Kerr-Newman black holes; thus they are dubbed acoustic clouds. We make the comparison between scalar clouds around Kerr black holes and acoustic clouds around the draining bathtub explicit by studying also the properties of scalar clouds around Kerr black holes enclosed in a cavity. Acoustic clouds suggest the possibility of testing, experimentally, the existence and properties of black hole clouds, using analog models.
Wave-Flow Interactions and Acoustic Streaming
Chafin, Clifford E
2016-01-01
The interaction of waves and flows is a challenging topic where a complete resolution has been frustrated by the essential nonlinear features in the hydrodynamic case. Even in the case of EM waves in flowing media, the results are subtle. For a simple shear flow of constant n fluid, incident radiation is shown to be reflected and refracted in an analogous manner to Snell's law. However, the beam intensities differ and the system has an asymmetry in that an internal reflection gap opens at steep incident angles nearly oriented with the shear. For EM waves these effects are generally negligible in real systems but they introduce the topic at a reduced level of complexity of the more interesting acoustic case. Acoustic streaming is suggested, both from theory and experimental data, to be associated with vorticity generation at the driver itself. Bounds on the vorticity in bulk and nonlinear effects demonstrate that the bulk sources, even with attenuation, cannot drive such a strong flow. A review of the velocity...
Laboratory Observations on Internal Solitary Wave Evolution over A Submarine Ridge
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Laboratory experiments were conducted in a wave flume on internal solitary wave (ISW) of depression and elevation types propagating over a submarine ridge in semicircular/triangular shape. Tests were arranged in series for combinations of submarine ridges of different heights and ISW of different amplitudes. The resultant wave motions were found differing from those of surface gravity waves. In deeper water, where an ISW of depression-type prevailed, the process of wave breaking displayed downward motion with continuous eddy on the front face of the ridge followed by upward motion towards the apex of the obstacle. Experimental results also suggested that blockage parameter ζ could be applied to classify various degrees of ISW-ridge interaction, i.e., ζ＜0.5 for weak interaction, 0.5＜ζ＜0.7 for moderate interaction, and 0.7＜ζ for wave breaking.
Noguchi, Y.; Yamada, T.; Otomori, M.; Izui, K.; Nishiwaki, S.
2015-11-01
This letter presents an acoustic metasurface that converts longitudinal acoustic waves into transverse elastic waves in an acoustic-elastic coupled system. Metasurface configurations are obtained by a level set-based topology optimization method, and we describe the mechanism that changes the direction of the wave motion. Numerical examples of 2D problems with prescribed frequencies of incident acoustic waves are provided, and transverse elastic wave amplitudes are maximized by manipulating the propagation of the acoustic waves. Frequency analysis reveals that each of the different metasurface designs obtained for different wavelengths of incident waves provides peak response at the target frequency.
On the orbital stability of Gaussian solitary waves in the log-KdV equation
Carles, Rémi; Pelinovsky, Dmitry
2014-12-01
We consider the logarithmic Korteweg-de Vries (log-KdV) equation, which models solitary waves in anharmonic chains with Hertzian interaction forces. By using an approximating sequence of global solutions of the regularized generalized KdV equation in H^1({R}) with conserved L2 norm and energy, we construct a weak global solution of the log-KdV equation in a subset of H^1({R}) . This construction yields conditional orbital stability of Gaussian solitary waves of the log-KdV equation, provided that uniqueness and continuous dependence of the constructed solution holds. Furthermore, we study the linearized log-KdV equation at the Gaussian solitary wave and prove that the associated linearized operator has a purely discrete spectrum consisting of simple purely imaginary eigenvalues in addition to the double zero eigenvalue. The eigenfunctions, however, do not decay like Gaussian functions but have algebraic decay. Using numerical approximations, we show that the Gaussian initial data do not spread out but produce visible radiation at the left slope of the Gaussian-like pulse in the time evolution of the linearized log-KdV equation.
Tang, Qunshu; Hobbs, Richard; Zheng, Chan; Biescas, Berta; Caiado, Camila
2016-06-01
Marine seismic reflection technique is used to observe the strong ocean dynamic process of nonlinear internal solitary waves (ISWs or solitons) in the near-surface water. Analysis of ISWs is problematical because of their transient nature and limitations of classical physical oceanography methods. This work explores a Markov Chain Monte Carlo (MCMC) approach to recover the temperature and salinity of ISW field using the seismic reflectivity data and in situ hydrographic data. The MCMC approach is designed to directly sample the posterior probability distributions of temperature and salinity which are the solutions of the system under investigation. The principle improvement is the capability of incorporating uncertainties in observations and prior models which then provide quantified uncertainties in the output model parameters. We tested the MCMC approach on two acoustic reflectivity data sets one synthesized from a CTD cast and the other derived from multichannel seismic reflections. This method finds the solutions faithfully within the significantly narrowed confidence intervals from the provided priors. Combined with a low frequency initial model interpreted from seismic horizons of ISWs, the MCMC method is used to compute the finescale temperature, salinity, acoustic velocity, and density of ISW field. The statistically derived results are equivalent to the conventional linearized inversion method. However, the former provides us the quantified uncertainties of the temperature and salinity along the whole section whilst the latter does not. These results are the first time ISWs have been mapped with sufficient detail for further analysis of their dynamic properties.
Equatorial Rossby Solitary Wave Under the External Forcing
Institute of Scientific and Technical Information of China (English)
FU Zun-Tao; LIU Shi-Kuo; LIU Shi-Da
2005-01-01
A simple shallow-water model with influence of external forcing on a β-plane is applied to investigate the nonlinear equatorial Rossby waves in a shear flow. By the perturbation method, the extended variable-coefficient KdV equation under an external forcing is derived for large amplitude equatorial Rossby wave in a shear flow. And then various periodic-like structures for these equatorial Rossby waves are obtained with the help of Jacobi elliptic functions.It is shown that the external forcing plays an important role in various periodic-like structures.
Surface acoustic wave propagation in graphene film
International Nuclear Information System (INIS)
Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals
Surface acoustic wave propagation in graphene film
Energy Technology Data Exchange (ETDEWEB)
Roshchupkin, Dmitry, E-mail: rochtch@iptm.ru; Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Irzhak, Dmitry [Institute of Microelectronics Technology and High-Purity Materials Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Ortega, Luc [Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS, UMR 8502, 91405 Orsay Cedex (France); Zizak, Ivo; Erko, Alexei [Institute for Nanometre Optics and Technology, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein Strasse 15, 12489 Berlin (Germany); Tynyshtykbayev, Kurbangali; Insepov, Zinetula [Nazarbayev University Research and Innovation System, 53 Kabanbay Batyr St., Astana 010000 (Kazakhstan)
2015-09-14
Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.
Simulation of dust-acoustic waves
International Nuclear Information System (INIS)
The authors use molecular dynamics (MD) and particle-in-cell (PIC) simulation methods to investigate the dispersion relation of dust-acoustic waves in a one-dimensional, strongly coupled (Coulomb coupling parameter Λ = ratio of the Coulomb energy to the thermal energy = 120) dusty plasma. They study both cases where the dust is represented by a small number of simulation particles that form into a regular array structure (crystal limit) as well as where the dust is represented by a much larger number of particles (fluid limit)
Energy Technology Data Exchange (ETDEWEB)
Guo Shimin [School of Mathematics and Statistics, Xi' an Jiaotong University, Xi' an 710049 (China); Research Group MAC 2, Centrum Wiskunde and Informatica, Amsterdam 1098XG (Netherlands); Wang Hongli [School of Business and Administration, Tongji University, Shanghai 200092 (China); Mei Liquan [School of Mathematics and Statistics, Xi' an Jiaotong University, Xi' an 710049 (China); Center for Computational Geosciences, Xi' an Jiaotong University, Xi' an 710049 (China)
2012-06-15
By combining the effects of bounded cylindrical geometry, azimuthal and axial perturbations, the nonlinear dust acoustic waves (DAWs) in an unmagnetized plasma consisting of negatively charged dust grains, nonextensive ions, and nonextensive electrons are studied in this paper. Using the reductive perturbation method, a (3 + 1)-dimensional variable-coefficient cylindrical Korteweg-de Vries (KdV) equation describing the nonlinear propagation of DAWs is derived. Via the homogeneous balance principle, improved F-expansion technique and symbolic computation, the exact traveling and solitary wave solutions of the KdV equation are presented in terms of Jacobi elliptic functions. Moreover, the effects of the plasma parameters on the solitary wave structures are discussed in detail. The obtained results could help in providing a good fit between theoretical analysis and real applications in space physics and future laboratory plasma experiments where long-range interactions are present.
Lotekar, Ajay; Kakad, Amar; Kakad, Bharati
2016-10-01
One-dimensional fluid simulation is performed for the unmagnetized plasma consisting of cold fluid ions and superthermal electrons. Such a plasma system supports the generation of ion acoustic (IA) waves. A standard Gaussian type perturbation is used in both electron and ion equilibrium densities to excite the IA waves. The evolutionary profiles of the IA waves are obtained by varying the superthermal index and the amplitude of the initial perturbation. This simulation demonstrates that the amplitude of the initial perturbation and the superthermal index play an important role in determining the time evolution and the characteristics of the generated IA waves. The initial density perturbation in the system creates charge separation that drives the finite electrostatic potential in the system. This electrostatic potential later evolves into the dispersive and nondispersive IA waves in the simulation system. The density perturbation with the amplitude smaller than 10% of the equilibrium plasma density evolves into the dispersive IA waves, whereas larger density perturbations evolve into both dispersive and nondispersive IA waves for lower and higher superthermal index. The dispersive IA waves are the IA oscillations that propagate with constant ion plasma frequency, whereas the nondispersive IA waves are the IA solitary pulses (termed as IA solitons in the stability region) that propagate with the constant wave speed. The characteristics of the stable nondispersive IA solitons are found to be consistent with the nonlinear fluid theory. To the best of our knowledge, this is the first fluid simulation study that has considered the superthermal distributions for the plasma species to model the electrostatic solitary waves.
Institute of Scientific and Technical Information of China (English)
XU Zhenhua; YIN Baoshu; YANG Hongwei; QI Jifeng
2012-01-01
Both large amplitude depression and elevation internal solitary waves (ISWs) were observed on the continental shelf of the northwest South China Sea (SCS) during the Wenchang Internal Wave Experiment.In this study,we investigate the characteristics of depression and elevation ISWs based on comparisons between observational results and internal wave theories.It is suggested that the large amplitude depression wave is better represented by the extended Korteweg-de Vries (EKdV) theory than by the KdV model,whereas the large amplitude elevation wave is in better agreement with the KdV equation than with the EKdV theory.Wave-induced forces on a supposed small-diameter cylindrical pile by depression and elevation waves are also estimated using the internal wave theory and Morison formula.The wave-induced force by elevation ISWs is rarely reported in the literature.It is found that the force induced by the elevation wave differs significantly from that by the depression wave,and the elevation wave generally produces greater force on the pile in the lower water column than the depression wave.These results show that ISWs in the study area can present a serious threat to ocean engineering structures,and should not be ignored in the design of oil platforms and ocean operations.
Simulating acoustic waves in spotted stars
Papini, Emanuele; Birch, Aaron C.; Gizon, Laurent; Hanasoge, Shravan M.
2015-05-01
Acoustic modes of oscillation are affected by stellar activity, however it is unclear how starspots contribute to these changes. Here we investigate the nonmagnetic effects of starspots on global modes with angular degree ℓ ≤ 2 in highly active stars, and characterize the spot seismic signature on synthetic light curves. We perform 3D time-domain simulations of linear acoustic waves to study their interaction with a model starspot. We model the spot as a 3D change in the sound speed stratification with respect to a convectively stable stellar background, built from solar Model S. We perform a parametric study by considering different depths and perturbation amplitudes. Exact numerical simulations allow the investigation of the wavefield-spot interaction beyond first order perturbation theory. The interaction of the axisymmetric modes with the starspot is strongly nonlinear. As mode frequency increases, the frequency shifts for radial modes exceed the value predicted by linear theory, while the shifts for the ℓ = 2,m = 0 modes are smaller than predicted by linear theory, with avoided-crossing-like patterns forming between the m = 0 and m = 1 mode frequencies. The nonlinear behavior increases with increasing spot amplitude and/or decreasing depth. Linear theory still reproduces the correct shifts for nonaxisymmetric modes. In the nonlinear regime the mode eigenfunctions are not pure spherical harmonics, but rather a mixture of different spherical harmonics. This mode mixing, together with the frequency changes, may lead to misidentification of the modes in the observed acoustic power spectra.
Analytical Interaction of the Acoustic Wave and Turbulent Flame
Institute of Scientific and Technical Information of China (English)
TENG Hong-Hui; JIANG Zong-Lin
2007-01-01
A modified resonance model of a weakly turbulent flame in a high-frequency acoustic wave is derived analytically.Under the mechanism of Darrieus-Landau instability, the amplitude of flame wrinkles, which is as functions of turbulence. The high perturbation wave number makes the resonance easier to be triggered but weakened with respect to the extra acoustic wave. In a closed burning chamber with the acoustic wave induced by the flame itself, the high perturbation wave number is to restrain the resonance for a realistic flame.
Measurement and modeling of bed shear stress under solitary waves
Digital Repository Service at National Institute of Oceanography (India)
Jayakumar, S.; Guard, P.A.; Baldock, T.E.
) < ~ 10 sup (5)). Measurements were carried out where the wave height to water depth (h/d) ratio varied between 0.12 and 0.68; maximum near bed velocity varied between 0.16 m/s and 0.51 m/s and the maximum total shear stress (sum of skin shear stress...
On extending the concept of double negativity to acoustic waves
Institute of Scientific and Technical Information of China (English)
CHAN C.T.; LI Jensen; FUNG K.H.
2006-01-01
The realization of double negative electromagnetic wave media, sometimes called left-handed materials (LHMs) or metamaterials, have drawn considerable attention in the past few years. We will examine the possibility of extending the concept to acoustic waves. We will see that acoustic metamaterials require both the effective density and bulk modulus to be simultaneously negative in the sense of an effective medium. If we can find a double negative (negative density and bulk modulus) acoustic medium, it will be an acoustic analogue of Veselago's medium in electromagnetism, and share many novel consequences such as negative refractive index and backward wave characteristics. We will give one example of such a medium.
Wave envelopes method for description of nonlinear acoustic wave propagation.
Wójcik, J; Nowicki, A; Lewin, P A; Bloomfield, P E; Kujawska, T; Filipczyński, L
2006-07-01
A novel, free from paraxial approximation and computationally efficient numerical algorithm capable of predicting 4D acoustic fields in lossy and nonlinear media from arbitrary shaped sources (relevant to probes used in medical ultrasonic imaging and therapeutic systems) is described. The new WE (wave envelopes) approach to nonlinear propagation modeling is based on the solution of the second order nonlinear differential wave equation reported in [J. Wójcik, J. Acoust. Soc. Am. 104 (1998) 2654-2663; V.P. Kuznetsov, Akust. Zh. 16 (1970) 548-553]. An incremental stepping scheme allows for forward wave propagation. The operator-splitting method accounts independently for the effects of full diffraction, absorption and nonlinear interactions of harmonics. The WE method represents the propagating pulsed acoustic wave as a superposition of wavelet-like sinusoidal pulses with carrier frequencies being the harmonics of the boundary tone burst disturbance. The model is valid for lossy media, arbitrarily shaped plane and focused sources, accounts for the effects of diffraction and can be applied to continuous as well as to pulsed waves. Depending on the source geometry, level of nonlinearity and frequency bandwidth, in comparison with the conventional approach the Time-Averaged Wave Envelopes (TAWE) method shortens computational time of the full 4D nonlinear field calculation by at least an order of magnitude; thus, predictions of nonlinear beam propagation from complex sources (such as phased arrays) can be available within 30-60 min using only a standard PC. The approximate ratio between the computational time costs obtained by using the TAWE method and the conventional approach in calculations of the nonlinear interactions is proportional to 1/N2, and in memory consumption to 1/N where N is the average bandwidth of the individual wavelets. Numerical computations comparing the spatial field distributions obtained by using both the TAWE method and the conventional approach
Visualization of Surface Acoustic Waves in Thin Liquid Films
Rambach, R. W.; Taiber, J.; C. M. L. Scheck; Meyer, C.; Reboud, J.; Cooper, J M; Franke, T.
2016-01-01
We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with anWe demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfl...
Mechanism of an acoustic wave impact on steel during solidification
K. Nowacki; P. Musiał; T. Lis
2013-01-01
Acoustic steel processing in an ingot mould may be the final stage in the process of quality improvement of a steel ingot. The impact of radiation and cavitation pressure as well as the phenomena related to the acoustic wave being emitted and delivered to liquid steel affect various aspects including the internal structure fragmentation, rigidity or density of steel. The article provides an analysis of the mechanism of impact of physical phenomena caused by an acoustic wave affecting the qual...
Solitary wave solutions to nonlinear evolution equations in mathematical physics
Indian Academy of Sciences (India)
Anwar Ja’afar Mohamad Jawad; M Mirzazadeh; Anjan Biswas
2014-10-01
This paper obtains solitons as well as other solutions to a few nonlinear evolution equations that appear in various areas of mathematical physics. The two analytical integrators that are applied to extract solutions are tan–cot method and functional variable approaches. The soliton solutions can be used in the further study of shallow water waves in (1+1) as well as (2+1) dimensions.
A model for large-amplitude internal solitary waves with trapped cores
Directory of Open Access Journals (Sweden)
K. R. Helfrich
2010-07-01
Full Text Available Large-amplitude internal solitary waves in continuously stratified systems can be found by solution of the Dubreil-Jacotin-Long (DJL equation. For finite ambient density gradients at the surface (bottom for waves of depression (elevation these solutions may develop recirculating cores for wave speeds above a critical value. As typically modeled, these recirculating cores contain densities outside the ambient range, may be statically unstable, and thus are physically questionable. To address these issues the problem for trapped-core solitary waves is reformulated. A finite core of homogeneous density and velocity, but unknown shape, is assumed. The core density is arbitrary, but generally set equal to the ambient density on the streamline bounding the core. The flow outside the core satisfies the DJL equation. The flow in the core is given by a vorticity-streamfunction relation that may be arbitrarily specified. For simplicity, the simplest choice of a stagnant, zero vorticity core in the frame of the wave is assumed. A pressure matching condition is imposed along the core boundary. Simultaneous numerical solution of the DJL equation and the core condition gives the exterior flow and the core shape. Numerical solutions of time-dependent non-hydrostatic equations initiated with the new stagnant-core DJL solutions show that for the ambient stratification considered, the waves are stable up to a critical amplitude above which shear instability destroys the initial wave. Steadily propagating trapped-core waves formed by lock-release initial conditions also agree well with the theoretical wave properties despite the presence of a "leaky" core region that contains vorticity of opposite sign from the ambient flow.
Classification of regimes of internal solitary waves transformation over a shelf-slope topography
Terletska, Kateryna; Maderich, Vladimir; Talipova, Tatiana; Brovchenko, Igor; Jung, Kyung Tae
2015-04-01
The internal waves shoal and dissipate as they cross abrupt changes of the topography in the coastal ocean, estuaries and in the enclosed water bodies. They can form near the coast internal bores propagating into the shallows and re-suspend seabed pollutants that may have serious ecological consequences. Internal solitary waves (ISW) with trapped core can transport masses of water and marine organisms for some distance. The transport of cold, low-oxygen waters results in nutrient pumping. These facts require development of classification of regimes of the ISWs transformation over a shelf-slope topography to recognize 'hot spots' of wave energy dissipation on the continental shelf. A new classification of regimes of internal solitary wave interaction with the shelf-slope topography in the framework of two-layer fluid is proposed. We introduce a new three-dimensional diagram based on parameters α ,β , γ. Here α is the nondimensional wave amplitude normalized on the thermocline thickness α = ain/h1 (α > 0), β is the blocking parameter introduced in (Talipova et al., 2013) that is the ratio of the height of the bottom layer on the the shelf step h2+ to the incident wave amplitude ain, β = h2+/ain (β > -3), and γ is the parameter inverse to the slope inclination (γ > 0.01). Two mechanisms are important during wave shoaling: (i) wave breaking resulting in mixing and (ii) changing of the polarity of the initial wave of depression on the slope. Range of the parameters at which wave breaking occurs can be defined using the criteria, obtained empirically (Vlasenko and Hutter, 2002). In the three-dimensional diagram this criteria is represented by the surface f1(β,γ) = 0 that separates the region of parameters where breaking takes place from the region without breaking. The polarity change surface f2(α,β) = 0 is obtained from the condition of equality of the depth of upper layer h1 to the depth of the lower layer h2. In the two-layer stratification waves of
AN EXPERIMENTAL OBSERVATION OF A SOLITARY WAVE IMPINGEMENT, RUN-UP AND OVERTOPPING ON A SEAWALL
Institute of Scientific and Technical Information of China (English)
LIN Ting-Chieh; HWANG Kao-Shu; HSIAO Shih-Chun; YANG Ray-Yeng
2012-01-01
A sequence of laboratory experiments using solitary waves was performed to model the effect of leading form of three types of tsunamis (a bore,an impinging wave and an overtopping wave) on a seawall on a sloping beach.The wave evolution process,impinging pressure along the seawall surface,total overtopping discharge behind the seawall and the maximum run-up height on the rear slope were measured and compared.Laboratory data were employed to re-examine relevant empirical formulae in the literature.The effect of the presence of the seawall in reducing maximum run-up height using the present setup was briefly discussed.The present data can be used for calibrating numerical and mathematical models.
Measurement and modelling of bed shear induced by solitary waves
Digital Repository Service at National Institute of Oceanography (India)
JayaKumar, S.
be considered in pipeline routing. 10.6. Future directions Bed shear stresses due to N-shaped waves were estimated using the method described in this thesis. However, due to want of time, this data was not considered in this thesis. The data pertaining to N....K.C. and Erali, D.R., 1974. Large diameter underwater pipeline for nuclear power plant designed against soil liquefaction. Offshore Technology Conference, Dallas, p.^pp. 597-606. Cokgor, S., 2002. Hydrodynamic forces on a partly buried cylinder exposed...
Energy Technology Data Exchange (ETDEWEB)
Bui Dinh, T. [Institute of Physics, University of Zielona Gora, ul. Prof. A. Szafrana 4a, 65-516 Zielona Gora (Poland); Vinh University, 182 Duong Le Duan, Nghe An (Viet Nam); Long, V. Cao [Institute of Physics, University of Zielona Gora, ul. Prof. A. Szafrana 4a, 65-516 Zielona Gora (Poland); Xuan, K. Dinh [Vinh University, 182 Duong Le Duan, Nghe An (Viet Nam); Wojciechowski, K.W. [Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznan (Poland)
2012-07-15
Results of numerical simulations are presented for propagation of solitary waves in an elastic rod of positive or negative Poisson's ratio, i.e. of a common or auxetic material. Splitting of various initial pulses during propagation into a sequence of solitary waves is considered in frames of a model which contains both quadratic and cubic nonlinear terms. The obtained results are compared with some exact analytic solutions, called solitons, what leads to the conclusion that the solitons describe well the more complicated wave fields which are obtained by numerical simulations. This is because the analytic solutions reflect complete balance between various orders of nonlinearity and dispersion. Collisions between some obtained solitary waves are also presented. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Riaud, Antoine; Charron, Eric; Bussonnière, Adrien; Matar, Olivier Bou
2015-01-01
From radio-electronics signal analysis to biological samples actuation, surface acoustic waves (SAW) are involved in a multitude of modern devices. Despite this versatility, SAW transducers developed up to date only authorize the synthesis of the most simple standing or progressive waves such as plane and focused waves. In particular, acoustical integrated sources able to generate acoustical vortices (the analogue of optical vortices) are missing. In this work, we propose a flexible tool based on inverse filter technique and arrays of SAW transducers enabling the synthesis of prescribed complex wave patterns at the surface of anisotropic media. The potential of this setup is illustrated by the synthesis of a 2D analog of 3D acoustical vortices, namely "swirling surface acoustic waves". Similarly to their 3D counterpart, they appear as concentric structures of bright rings with a phase singularity in their center resulting in a central dark spot. Swirling SAW can be useful in fragile sensors whose neighborhood...
An effective absorbing boundary algorithm for acoustical wave propagator
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper, Berenger's perfectly matched layer (PML) absorbing boundary condition for electromagnetic waves is introduced as the truncation area of the computational domain to absorb one-dimensional acoustic wave for the scheme of acoustical wave propagator (AWP). To guarantee the efficiency of the AWP algorithm, a regulated propagator matrix is derived in the PML medium.Numerical simulations of a Gaussian wave packet propagating in one-dimensional duct are carried out to illustraze the efficiency of the combination of PML and AWP. Compared with the traditional smoothing truncation windows technique of AWP, this scheme shows high computational accuracy in absorbing acoustic wave when the acoustical wave arrives at the computational edges. Optimal coefficients of the PML configurations are also discussed.
Ion-acoustic cnoidal waves in a quantum plasma
Mahmood, Shahzad
2016-01-01
Nonlinear ion-acoustic cnoidal wave structures are studied in an unmagnetized quantum plasma. Using the reductive perturbation method, a Korteweg-de Vries equation is derived for appropriate boundary conditions and nonlinear periodic wave solutions are obtained. The corresponding analytical solution and numerical plots of the ion-acoustic cnoidal waves and solitons in the phase plane are presented using the Sagdeev pseudo-potential approach. The variations in the nonlinear potential of the ion-acoustic cnoidal waves are studied at different values of quantum parameter $H_{e}$ which is the ratio of electron plasmon energy to electron Fermi energy defined for degenerate electrons. It is found that both compressive and rarefactive ion-acoustic cnoidal wave structures are formed depending on the value of the quantum parameter. The dependence of the wavelength and frequency on nonlinear wave amplitude is also presented.
Raising Photoemission Efficiency with Surface Acoustic Waves
Energy Technology Data Exchange (ETDEWEB)
A. Afanasev, F. Hassani, C.E. Korman, V.G. Dudnikov, R.P. Johnson, M. Poelker, K.E.L. Surles-Law
2012-07-01
We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.
Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms
Lay, Erin H.; Shao, Xuan-Min; Kendrick, Alexander K.; Carrano, Charles S.
2015-07-01
Acoustic waves with periods of 2-4 min and gravity waves with periods of 6-16 min have been detected at ionospheric heights (250-350 km) using GPS total electron content measurements. The area disturbed by these waves and the wave amplitudes have been associated with underlying thunderstorm activity. A statistical study comparing Next Generation Weather Radar thunderstorm measurements with ionospheric acoustic and gravity waves in the midlatitude U.S. Great Plains region was performed for the time period of May-July 2005. An increase of ionospheric acoustic wave disturbed area and amplitude is primarily associated with large thunderstorms (mesoscale convective systems). Ionospheric gravity wave disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.
Propagation of plate acoustic waves in contact with fluid medium
Ghatadi Suraji, Nagaraj
The characteristics of acoustic waves propagating in thin piezoelectric plates in the presence of a fluid medium contacting one or both of the plate surfaces are investigated. If the velocity of plate wave in the substrate is greater than velocity of bulk wave in the fluid, then a plate acoustic wave (PAW) traveling in the substrate will radiate a bulk acoustic wave (BAW) in the fluid. It is found that, under proper conditions, efficient conversion of energy from plate acoustic waves to bulk acoustic waves and vice versa can be obtained. For example, using the fundamental anti symmetric plate wave mode (A0 mode) propagating in a lithium niobate substrate and water as the fluid, total mode conversion loss (PAW to BAW and back from BAW to PAW) of less than 3 dB has been obtained. This mode conversion principle can be used to realize miniature, high efficiency transducers for use in ultrasonic flow meters. Similar type of transducer based on conversion of energy from surface acoustic wave (SAW) to bulk acoustic wave (BAW) has been developed previously. The use of plate waves has several advantages. Since the energy of plate waves is present on both plate surfaces, the inter digital transducer (IDT) can be on the surface opposite from that which is in contact with the fluid. This protects the IDT from possible damage due to the fluid and also simplifies the job of making electrical connections to the IDT. Another advantage is that one has wider choice of substrate materials with plate waves than is the case with SAWs. Preliminary calculations indicate that the mode conversion principle can also be used to generate and detect ultrasonic waves in air. This has potential applications for realizing transducers for use in non-contact ultrasonic's. The design of an ASIC (Application Specific Integrated Circuit) chip containing an amplifier and frequency counter for use with ultrasonic transducers is also presented in this thesis.
Propagation of ion-acoustic waves in a dusty plasma with non-isothermal electrons
Indian Academy of Sciences (India)
K K Mondal
2007-08-01
For an unmagnetised collisionless plasma consisting of warm ions, non-isothermal electrons and cold, massive and charged dust grains, the Sagdeev potential equation, considering both ion dynamics and dust dynamics has been derived. It has been observed that the Sagdeev potential () exists only for > 0 up to an upper limit ( ≃ 1.2). This implies the possibility of existence of compressive solitary wave in the plasma. Exhaustive numerics done for both the large-amplitude and small-amplitude ion-acoustic waves have revealed that various parameters, namely, ion temperature, non-isothermality of electrons, Mach numbers etc. have considerable impact on the amplitude as well as the width of the solitary waves. Dependence of soliton profiles on the ion temperature and the Mach number has also been graphically displayed. Moreover, incorporating dust-charge fluctuation and non-isothermality of electrons, a non-linear equation relating the grain surface potential to the electrostatic potential has been derived. It has been solved numerically and interdependence of the two potentials for various ion temperatures and orders of non-isothermality has been shown graphically.
Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris
2013-01-01
A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.
Experiments on the interactions between impurities and solitary waves in lattice model
Institute of Scientific and Technical Information of China (English)
ZHU; Yifei(朱逸斐); CHEN; Weizhong; (陈伟中); Lü; Lei; (吕镭)
2003-01-01
The interactions between solitary waves and impurities have been studied experimentally in a 1D nonlinear coupled pendulum chain under vertical excitation. The mass and the coupling are unique, except a single pendulum with length impurity in the chain. The experiment reveals: the long impurity repels breather and attracts kink while the short one attracts breather and repels kink under higher frequency driving, and the long impurity attracts breather and repels kink while the short one repels breather and attracts kink under the lower frequency driving. These results prove the current theoretical prediction based on continuum-limit approximation.
Flat Solitary Waves due to a Submerged Body Moving in a Stratified Fluid
Institute of Scientific and Technical Information of China (English)
WEI Gang; SU Xiao-Bing; LU Dong-Qiang; YOU Yun-Xiang; DAI Shi-Qiang
2008-01-01
A theoretical model for interaction of a submerged moving body with the conjugate flow in a three-layer fluid is proposed to depict the internal flat solitary wave, which is observed in experiments conducted by the present authors. A set of coupled nonlinear algebraic equations is derived for the interracial displacements. The numerical results indicate that (a) the conjugate flow due to a two-dimensional body moving at the bottom possesses an apparent behaviour with two convex interfaces; (b) the solution satisfying the existence criterion is always unique near the relatively stable state of system. Theoretical analysis is qualitatively consistent with the experimental results obtained.
Excitation spectra of solitary waves in scalar field models with polynomial self-interaction
Gani, Vakhid A; Lizunova, Mariya A; Mrozovskaya, Elizaveta V
2016-01-01
We study excitations of solitary waves -- the kinks -- in scalar models with degree eight polynomial self-interaction in (1+1) dimensions. We perform numerical studies of scattering of two kinks with an exponential asymptotic off each other and analyse the occurring resonance phenomena. We connect these phenomena to the energy exchange between the translational and the vibrational modes of the colliding kinks. We also point out that the interaction of two kinks with power-law asymptotic can lead to a long-range interaction between the two kinks.
Rickard, Graham; O'Callaghan, Joanne; Popinet, Stéphane
Two-dimensional, non-linear, Boussinesq, non-hydrostatic simulations of internal solitary waves breaking and running up uniform slopes have been performed using an adaptive, finite volume fluid code "Gerris". It is demonstrated that the Gerris dynamical core performs well in this specific but important geophysical context. The "semi-structured" nature of Gerris is exploited to enhance model resolution along the slope where wave breaking and run-up occur. Comparison with laboratory experiments reveals that the generation of single and multiple turbulent surges ("boluses") as a function of slope angle is consistently reproduced by the model, comparable with observations and previous numerical simulations, suggesting aspects of the dynamical energy transfers are being represented by the model in two dimensions. Adaptivity is used to explore model convergence of the wave breaking dynamics, and it is shown that significant cpu memory and time savings are possible with adaptivity.
Flow and Turbulence at Rubble-Mound Breakwater Armor Layers under Solitary Wave
DEFF Research Database (Denmark)
Jensen, Bjarne; Christensen, Erik Damgaard; Sumer, B. Mutlu;
2015-01-01
to the breakwater, and (3) a porous breakwater where the porous core was added below the breakwater front. One breakwater slope of 1:1.5 was applied. In this paper the focus is on the details of a single sequence of wave approach, run-up, and rundown. To isolate this sequence the experiments were performed applying......This paper presents the results of an experimental investigation of the flow and turbulence at the armor layer of rubble-mound breakwaters during wave action. The study focused on the details of the flow and turbulence in the armor layer and on the effect of the porous core on flow and stability...... a solitary wave. The individual sources of turbulence generation were distinguished using Laser Doppler anemometry measurements, and the effect of the armor layer and porous core was described in terms of a reduced impact of the rundown process, production of lee wake turbulence, and less transport...
Energy Technology Data Exchange (ETDEWEB)
Burde, Georgy I, E-mail: georg@bgu.ac.i [Jacob Blaustein Institutes for Desert Research, Ben-Gurion University, Sede Boker Campus 84990 (Israel)
2010-02-26
New types of exact explicit solitary wave solutions of the higher order KdV equations are identified by applying a direct method designed specifically for constructing solitary wave solutions of evolution equations. The first type is the 'generalized Kaup-Kupershmidt' (GKK) solitary waves, which unify the structures of the sech{sup 2} KdV-like soliton and the Kaup-Kupershmidt soliton and also provide solutions of some other equations. One of those equations is found to possess the multi-soliton solutions which makes it a good candidate for being integrable in terms of the GKK solitons. Another type of solutions of the higher order KdV equations identified by applying the method represents the steady-state localized structures. The variety of equations possessing such solutions includes the integrable (in terms of the sech{sup 2} solitons) Sawada-Kotera equation which thus appears to provide the localized solutions of two types.
A metasurface carpet cloak for electromagnetic, acoustic and water waves
Yihao Yang; Huaping Wang; Faxin Yu; Zhiwei Xu; Hongsheng Chen
2016-01-01
We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the re...
Institute of Scientific and Technical Information of China (English)
兰朝凤; 李凤臣; 陈欢; 卢迪; 杨德森; 张梦
2015-01-01
Based on the Burgers equation and Manley-Rowe equation, the derivation about nonlinear interaction of the acoustic waves has been done in this paper. After nonlinear interaction among the low-frequency weak waves and the pump wave, the analytical solutions of acoustic waves’ amplitude in the field are deduced. The relationship between normalized energy of high-frequency and the change of acoustic energy before and after the nonlinear interaction of the acoustic waves is analyzed. The experimental results about the changes of the acoustic energy are presented. The study shows that new frequencies are generated and the energies of the low-frequency are modulated in a long term by the pump waves, which leads the energies of the low-frequency acoustic waves to change in the pulse trend in the process of the nonlinear interaction of the acoustic waves. The increase and decrease of the energies of the low-frequency are observed under certain typical conditions, which lays a foundation for practical engineering applications.
The structure and stability of mode-2 internal solitary-like waves
Carr, Magda; Davies, Peter; Hoebers, Ruud
2015-04-01
Recent observational examples of Mode-2 internal solitary-like waves (ISWs) in the ocean (e.g. Yang et al., 2009; Schroyer et al., 2010) have motivated modelling studies. The present laboratory study investigates the structure and stability of mode-2 ISWs. A rank-ordered train of mode-2 ISWs is generated using a lock release configuration. The pycnocline is centred either on the mid-depth of the water column (the 0% offset case) or it is offset in the positive vertical direction by a fraction of 5%, 10% or 20% of the total fluid depth. It is found that offsetting the pycnocline has little effect on the basic wave properties but it does significantly affect wave stability. Instability takes the form of small K-H-like billows in the rear of the wave and small scale overturning in the core of the wave. In the 0% offset case, instability occurs on both the upper and lower interfaces of the pycnocline and is similar in extent and vigour over the two interfaces. As the offset percentage is increased, however, instability is more pronounced on the lower interface with little or no evidence of instability being observed on the upper interface. In the 20% offset case a mode-1 tail is associated with the wave and the wave characteristics resemble qualitatively the recent field observations of Shroyer et al., (2010).
NUMERICAL STUDIES OF INTERNAL SOLITARY WAVE GENERATION AND EVOLUTION BY GRAVITY COLLAPSE
Institute of Scientific and Technical Information of China (English)
LIN Zhen-hua; SONG Jin-bao
2012-01-01
In this study,an analysis on the internal wave generation via the gravity collapse mechanism is carried out based on the theoretical formulation and the numerical simulation.With the linear theoretical model,a rectangle shape wave is generated and propagates back and forth in the domain,while a two-dimensional non-hydrostatic numerical model could reproduce all the observed phenomena in the laboratory experiments conducted by Chen et al.(2007),and the related process realistically.The model results further provide more quantitative information in the whole domain,thus allowing an in depth understanding of the corresponding internal solitary wave generation and propagation.It is shown that the initial type of the internal wave is determined by the relative height between the perturbation and the environmental density interface,while the final wave type is related to the relative height of the upper and lower layers of the environmental fluid.The shape of the internal wave generated is consistent with that predicted by the KdV and EKdV theories if its amplitude is small,as the amplitude becomes larger,the performance of the EKdV becomes better after the wave adjusts itself to the ambient stratification and reaches an equilibrium state between the nonlinear and dispersion effects.The evolution of the mechanical energy is also analyzed.
Waveform inversion of acoustic waves for explosion yield estimation
Kim, K.; Rodgers, A.
2016-07-01
We present a new waveform inversion technique to estimate the energy of near-surface explosions using atmospheric acoustic waves. Conventional methods often employ air blast models based on a homogeneous atmosphere, where the acoustic wave propagation effects (e.g., refraction and diffraction) are not taken into account, and therefore, their accuracy decreases with increasing source-receiver distance. In this study, three-dimensional acoustic simulations are performed with a finite difference method in realistic atmospheres and topography, and the modeled acoustic Green's functions are incorporated into the waveform inversion for the acoustic source time functions. The strength of the acoustic source is related to explosion yield based on a standard air blast model. The technique was applied to local explosions (structure. The presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.
Louis, H; Tlidi, M; Louvergneaux, E
2016-07-11
We perform a statistical analysis of the optical solitary wave propagation in an ultra-slow stochastic non-local focusing Kerr medium such as liquid crystals. Our experimental results show that the localized beam trajectory presents a dynamical random walk whose beam position versus the propagation distance z depicts two different kind of evolutions A power law is found for the beam position standard deviation during the first stage of propagation. It obeys approximately z3/2 up to ten times the power threshold for solitary wave generation. PMID:27410887
Effects of Charge in Heavy Ions on Solitary Kinetic Alfvén Waves in Double-Ion Plasmas
Institute of Scientific and Technical Information of China (English)
YANG Lei; WU De-Jin
2006-01-01
@@ After the charge of heavy ions is considered, a Sagdeev equation is obtained for the solitary kinetic Alfvén waves (SKAWs) in a low-β(me/mp＜＜β＜＜1 or mp/me＞＞α＞＞1), three-component (electrons, protons, and highly charged heavy ions) plasma. Numerical results show that the charge number q of heavy ions can cause the width of the solitary structure to decrease, but increase for the maximum of electron density nem≤1.2 and the initial abundance of heavy ions Cb0 ≤ 0.1. The parallel phase speed of the waves increases with larger q.
Directory of Open Access Journals (Sweden)
J. S. Pickett
2009-06-01
Full Text Available Electrostatic Solitary Waves (ESWs have been observed by several spacecraft in the current layers of Earth's magnetosphere since 1982. ESWs are manifested as isolated pulses (one wave period in the high time resolution waveform data obtained on these spacecraft. They are thus nonlinear structures generated out of nonlinear instabilities and processes. We report the first observations of ESWs associated with the onset of a super-substorm that occurred on 24 August 2005 while the Cluster spacecraft were located in the magnetotail at around 18–19 R_{E} and moving northward from the plasma sheet to the lobes. These ESWs were detected in the waveform data of the WBD plasma wave receiver on three of the Cluster spacecraft. The majority of the ESWs were detected about 5 min after the super-substorm onset during which time 1 the PEACE electron instrument detected significant field-aligned electron fluxes from a few 100 eV to 3.5 keV, 2 the EDI instrument detected bursts of field-aligned electron currents, 3 the FGM instrument detected substantial magnetic fluctuations and the presence of Alfvén waves, 4 the STAFF experiment detected broadband electric and magnetic waves, ion cyclotron waves and whistler mode waves, and 5 CIS detected nearly comparable densities of H+ and O+ ions and a large tailward H+ velocity. We compare the characteristics of the ESWs observed during this event to those created in the laboratory at the University of California-Los Angeles Plasma Device (LAPD with an electron beam. We find that the time durations of both space and LAPD ESWs are only slightly larger than the respective local electron plasma periods, indicating that electron, and not ion, dynamics are responsible for generation of the ESWs. We have discussed possible mechanisms for generating the ESWs in space, including the beam and kinetic Buneman type instabilities and the acoustic instabilities. Future studies will examine these mechanisms in
Xie, Weifeng; Fan, Chenglei; Yang, Chunli; Lin, Sanbao
2016-03-01
As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius. PMID:26558995
Xie, Weifeng; Fan, Chenglei; Yang, Chunli; Lin, Sanbao
2016-03-01
As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius.
Persistent currents supported by solitary waves in toroidal Bose-Einstein condensates
Muñoz Mateo, A.; Gallemí, A.; Guilleumas, M.; Mayol, R.
2015-06-01
We analyze the nucleation of persistent currents in Bose-Einstein condensates of ultracold gases confined in a ring. This phenomenon has been recently investigated in an experiment [S. Eckel, J. G. Lee, F. Jendrzejewski, N. Murray, C. W. Clark, C. J. Lobb, W. D. Phillips, M. Edwards, and G. K. Campbell, Nature (London) 506, 200 (2014), 10.1038/nature12958], where hysteresis loops have been observed in the activation of quantized persistent currents by rotating weak links. In this work, we demonstrate the existence of three-dimensional stationary currents with nonquantized angular momentum. They are generated by families of solitary waves that exhibit a continuous variation in the angular momentum and provide a bridge between different winding numbers. We show that the size of hysteresis loops is determined by the range of existence within the weak link region of solitary waves which configure the energy barrier preventing phase slips. The barrier vanishes when the critical rotation leads winding number and solitonic states to a matching configuration. At this point, Landau and Feynman criteria for phase slips meet: the fluid flow reaches the local speed of sound, and stationary vortex lines (which are the building blocks of multidimensional solitons) can be excited inside the system.
Vlasov Simulation of Electrostatic Solitary Structures in Multi-Component Plasmas
Umeda, Takayuki; Ashour-Abdalla, Maha; Pickett, Jolene S.; Goldstein, Melvyn L.
2012-01-01
Electrostatic solitary structures have been observed in the Earth's magnetosheath by the Cluster spacecraft. Recent theoretical work has suggested that these solitary structures are modeled by electron acoustic solitary waves existing in a four-component plasma system consisting of core electrons, two counter-streaming electron beams, and one species of background ions. In this paper, the excitation of electron acoustic waves and the formation of solitary structures are studied by means of a one-dimensional electrostatic Vlasov simulation. The present result first shows that either electron acoustic solitary waves with negative potential or electron phase-space holes with positive potential are excited in four-component plasma systems. However, these electrostatic solitary structures have longer duration times and higher wave amplitudes than the solitary structures observed in the magnetosheath. The result indicates that a high-speed and small free energy source may be needed as a fifth component. An additional simulation of a five-component plasma consisting of a stable four-component plasma and a weak electron beam shows the generation of small and fast electron phase-space holes by the bump-on-tail instability. The physical properties of the small and fast electron phase-space holes are very similar to those obtained by the previous theoretical analysis. The amplitude and duration time of solitary structures in the simulation are also in agreement with the Cluster observation.
Groeskamp, S.; Nauw, J.J.; Maas, L.
2011-01-01
Despite vigorous tidal and wind mixing, observations in an estuarine tidal inlet in the Wadden Sea show that during part of the tidal cycle, vertical stratification and internal waves may still develop. Acoustic Doppler current profiler (ADCP) and conductivity, temperature, depth observations, colle
Nonlinear propagation and control of acoustic waves in phononic superlattices
Jiménez, Noé; Picó, Rubén; García-Raffi, Lluís M; Sánchez-Morcillo, Víctor J
2015-01-01
The propagation of intense acoustic waves in a one-dimensional phononic crystal is studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength, therefore Bragg effects such as band-gaps appear. We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g. cubic) nonlinearities, or extremely linear media (where distortion can be cancelled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime.
Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes
Ofman, Leon
2001-01-01
The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear. time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that nonlinear waves are generated in coronal holes by torsional Alfv\\'{e}n waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the, fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature. and magnetic field geometry,) that will become available from the recently launched SOHO spacecraft.
Application of the SPH method to solitary wave impact on an offshore platform
Pan, K.; IJzermans, R. H. A.; Jones, B. D.; Thyagarajan, A.; van Beest, B. W. H.; Williams, J. R.
2016-04-01
This paper investigates the interaction between large waves and floating offshore structures. Here, the fluid-structure interaction is considered using the weakly compressible smoothed particle hydrodynamics (SPH) method. To ensure the applicability of this method, we validate its prediction for fluid forces and rigid-body motion against two sets of experimental data. These are impact due to dam break, and wave induced motion of a floating cube. For the dam break problem, the SPH method is used to predict impact forces on a rectangular column located downstream. In the second case of a floating cube, the SPH method simulates the motion of a buoyant cube under the action of induced waves, where a wall placed upstream of the cube is displaced sinusoidally to induce waves. In both cases, the SPH framework implemented is able to accurately reproduce the experimental results. Following validation, we apply this framework to simulation of a toy model of a tension-leg platform upon impact of a large solitary wave. This analysis shows that the platform may be pulled into the water by stretched tension legs, where the extension of the tension legs also governs the rotational behavior of the platform. The result also indicates that a tension-leg platform is very unlikely to topple over during the arrival of an extreme wave.
Solitary Wave Solutions of the Boussinesq Equation and Its Improved Form
Directory of Open Access Journals (Sweden)
Reza Abazari
2013-01-01
Full Text Available This paper presents the general case study of previous works on generalized Boussinesq equations, (Abazari, 2011 and (Kılıcman and Abazari, 2012, that focuses on the application of G′/G-expansion method with the aid of Maple to construct more general exact solutions for the coupled Boussinesq equations. In this work, the mentioned method is applied to construct more general exact solutions of Boussinesq equation and improved Boussinesq equation, which the French scientist Joseph Valentin Boussinesq (1842–1929 described in the 1870s model equations for the propagation of long waves on the surface of water with small amplitude. Our work is motivated by the fact that the G′/G-expansion method provides not only more general forms of solutions but also periodic, solitary waves and rational solutions. The method appears to be easier and faster by means of a symbolic computation.
Complex solitary waves and soliton trains in KdV and mKdV equations
Modak, Subhrajit; Singh, Akhil Pratap; Panigrahi, Prasanta Kumar
2016-06-01
We demonstrate the existence of complex solitary wave and periodic solutions of the Korteweg-de Vries (KdV) and modified Korteweg-de Vries (mKdV) equations. The solutions of the KdV (mKdV) equation appear in complex-conjugate pairs and are even (odd) under the simultaneous actions of parity (𝓟) and time-reversal (𝓣) operations. The corresponding localized solitons are hydrodynamic analogs of Bloch soliton in magnetic system, with asymptotically vanishing intensity. The 𝓟𝓣-odd complex soliton solution is shown to be iso-spectrally connected to the fundamental sech2 solution through supersymmetry. Physically, these complex solutions are analogous to the experimentally observed grey solitons of non-liner Schödinger equation, governing the dynamics of shallow water waves and hence may also find physical verification.
Kinetic Alfven solitary waves in a magnetized plasma with superthermal electrons
International Nuclear Information System (INIS)
A study of the ion Larmor radius effects on the solitary kinetic Alfven waves (SKAWs) in a magnetized plasma with superthermal electrons is presented by employing the kinetic theory. The linear dispersion relation of SKAW is shown to depend on the superthermal parameter κ, ion to electron temperature ratio, and the angle of wave propagation. Using the Sagdeev potential approach, the energy balance equation has been derived to study the dynamics of SKAWs. The effects of various plasma parameters are investigated for the propagation of SKAWs. It is shown that only compressive solitons can exist and in the Maxwellian limit our results are in good agreement with previous studies. Further, the characteristics of small amplitude SKAWs are investigated. Present study could be useful for the understanding of SKAWs in a low β plasma in astrophysical environment, where particle distributions are superthermal in nature
Kinetic Alfven solitary waves in a magnetized plasma with superthermal electrons
Energy Technology Data Exchange (ETDEWEB)
Panwar, A., E-mail: anurajrajput@gmail.com, E-mail: ryu201@postech.ac.kr, E-mail: bainsphysics@yahoo.co.in; Ryu, C. M., E-mail: anurajrajput@gmail.com, E-mail: ryu201@postech.ac.kr, E-mail: bainsphysics@yahoo.co.in [POSTECH, Hyoja-Dong San 31, KyungBuk, Pohang 790-784 (Korea, Republic of); Bains, A. S., E-mail: anurajrajput@gmail.com, E-mail: ryu201@postech.ac.kr, E-mail: bainsphysics@yahoo.co.in [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatchewan S7N5E2 (Canada)
2015-09-15
A study of the ion Larmor radius effects on the solitary kinetic Alfven waves (SKAWs) in a magnetized plasma with superthermal electrons is presented by employing the kinetic theory. The linear dispersion relation of SKAW is shown to depend on the superthermal parameter κ, ion to electron temperature ratio, and the angle of wave propagation. Using the Sagdeev potential approach, the energy balance equation has been derived to study the dynamics of SKAWs. The effects of various plasma parameters are investigated for the propagation of SKAWs. It is shown that only compressive solitons can exist and in the Maxwellian limit our results are in good agreement with previous studies. Further, the characteristics of small amplitude SKAWs are investigated. Present study could be useful for the understanding of SKAWs in a low β plasma in astrophysical environment, where particle distributions are superthermal in nature.
Estimating propagation velocity through a surface acoustic wave sensor
Xu, Wenyuan; Huizinga, John S.
2010-03-16
Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.
Modulation of cavity-polaritons by surface acoustic waves
DEFF Research Database (Denmark)
de Lima, M. M.; Poel, Mike van der; Hey, R.;
2006-01-01
We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations.......We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations....
Optical transition radiation in presence of acoustic waves
Mkrtchyan, A R; Saharian, A A
2009-01-01
Transition radiation from relativistic electrons is investigated in an ultrasonic superlattice excited in a finite thickness plate. In the quasi-classical approximation formulae are derived for the vector potential of the electromagnetic field and for the spectral-angular distribution of the radiation intensity. The acoustic waves generate new resonance peaks in the spectral and angular distribution of the radiation intensity. The heights of the peaks can be tuned by choosing the parameters of the acoustic wave.
Chirped solitary pulses for a nonic nonlinear Schrödinger equation on a continuous-wave background
Triki, Houria; Porsezian, K.; Choudhuri, Amitava; Dinda, P. Tchofo
2016-06-01
A class of derivative nonlinear Schrödinger equation with cubic-quintic-septic-nonic nonlinear terms describing the propagation of ultrashort optical pulses through a nonlinear medium with higher-order Kerr responses is investigated. An intensity-dependent chirp ansatz is adopted for solving the two coupled amplitude-phase nonlinear equations of the propagating wave. We find that the dynamics of field amplitude in this system is governed by a first-order nonlinear ordinary differential equation with a tenth-degree nonlinear term. We demonstrate that this system allows the propagation of a very rich variety of solitary waves (kink, dark, bright, and gray solitary pulses) which do not coexist in the conventional nonlinear systems that have appeared so far in the literature. The stability of the solitary wave solution under some violation on the parametric conditions is investigated. Moreover, we show that, unlike conventional systems, the nonlinear Schrödinger equation considered here meets the special requirements for the propagation of a chirped solitary wave on a continuous-wave background, involving a balance among group velocity dispersion, self-steepening, and higher-order nonlinearities of different nature.
Acoustic Kappa-Density Fluctuation Waves in Suprathermal Kappa Function Fluids
Collier, Michael R.; Roberts, Aaron; Vinas, Adolfo
2007-01-01
We describe a new wave mode similar to the acoustic wave in which both density and velocity fluctuate. Unlike the acoustic wave in which the underlying distribution is Maxwellian, this new wave mode occurs when the underlying distribution is a suprathermal kappa function and involves fluctuations in the power law index, kappa. This wave mode always propagates faster than the acoustic wave with an equivalent effective temperature and becomes the acoustic wave in the Maxwellian limit as kappa g...
Bagheri, Abdollah
The in-situ measurement of thermal stress in civil and mechanical structures may prevent structural anomalies such as unexpected buckling. In the first half of the dissertation, we present a study where highly nonlinear solitary waves (HNSWs) were utilized to measure axial stress in slender beams. HNSWs are compact non-dispersive waves that can form and travel in nonlinear systems such as one-dimensional chains of particles. The effect of the axial stress acting in a beam on the propagation of HNSWs was studied. We found that certain features of the solitary waves enable the measurement of the stress. In general, most guided ultrasonic waves (GUWs)-based health monitoring approaches for structural waveguides are based on the comparison of testing data to baseline data. In the second half of the dissertation, we present a study where some baseline-free signal processing algorithms were presented and applied to numerical and experimental data for the structural health monitoring (SHM) of underwater or dry structures. The algorithms are based on one or more of the following: continuous wavelet transform, empirical mode decomposition, Hilbert transform, competitive optimization algorithm, probabilistic methods. Moreover, experimental data were also processed to extract some features from the time, frequency, and joint time-frequency domains. These features were then fed to a supervised learning algorithm based on artificial neural networks to classify the types of defect. The methods were validated using the numerical model of a plate and a pipe, and the experimental study of a plate in water. In experiment, the propagation of ultrasonic waves was induced by means of laser pulses or transducer and detected with an array of immersion transducers. The results demonstrated that the algorithms are effective, robust against noise, and able to localize and classify the damage.
Nozzleless Spray Cooling Using Surface Acoustic Waves
Ang, Kar Man; Yeo, Leslie; Friend, James; Hung, Yew Mun; Tan, Ming Kwang
2015-11-01
Due to its reliability and portability, surface acoustic wave (SAW) atomization is an attractive approach for the generation of monodispersed microdroplets in microfluidics devices. Here, we present a nozzleless spray cooling technique via SAW atomization with key advantage of downward scalability by simply increasing the excitation frequency. With generation of micron size droplets through surface destabilization using SAW, the clogging issues commonly encountered by spraying nozzle can be neutralized. Using deionised water, cooling is improved when the atomization rate is increased and the position of the device is optimized such that the atomized droplets can be easily seeded into the upstream of the flow circulation. Cooling is further improved with the use of nanofluids; a suspension of nanoparticles in water. By increasing nanoparticle mass concentration from 1% to 3%, cooling is enhanced due to the deposition and formation of nanoparticle clusters on heated surface and eventually increase the surface area. However, further increase the concentration to 10% reduces the cooling efficiency due to drastic increase in viscosity μ that leads to lower atomization rate which scales as ṁ ~μ - 1 / 2 .
Surface Acoustic Wave (SAW Vibration Sensors
Directory of Open Access Journals (Sweden)
Jerzy Filipiak
2011-12-01
Full Text Available In the paper a feasibility study on the use of surface acoustic wave (SAW vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.
Surface acoustic wave devices for sensor applications
Bo, Liu; Xiao, Chen; Hualin, Cai; Mohammad, Mohammad Ali; Xiangguang, Tian; Luqi, Tao; Yi, Yang; Tianling, Ren
2016-02-01
Surface acoustic wave (SAW) devices have been widely used in different fields and will continue to be of great importance in the foreseeable future. These devices are compact, cost efficient, easy to fabricate, and have a high performance, among other advantages. SAW devices can work as filters, signal processing units, sensors and actuators. They can even work without batteries and operate under harsh environments. In this review, the operating principles of SAW sensors, including temperature sensors, pressure sensors, humidity sensors and biosensors, will be discussed. Several examples and related issues will be presented. Technological trends and future developments will also be discussed. Project supported by the National Natural Science Foundation of China (Nos. 60936002, 61025021, 61434001, 61574083), the State Key Development Program for Basic Research of China (No. 2015CB352100), the National Key Project of Science and Technology (No. 2011ZX02403-002) and the Special Fund for Agroscientific Research in the Public Interest of China (No. 201303107). M.A.M is additionally supported by the Postdoctoral Fellowship (PDF) program of the Natural Sciences and Engineering Research Council (NSERC) of Canada and the China Postdoctoral Science Foundation (CPSF).
Nonlinear acoustic waves in micro-inhomogeneous solids
Nazarov, Veniamin
2014-01-01
Nonlinear Acoustic Waves in Micro-inhomogeneous Solids covers the broad and dynamic branch of nonlinear acoustics, presenting a wide variety of different phenomena from both experimental and theoretical perspectives. The introductory chapters, written in the style of graduate-level textbook, present a review of the main achievements of classic nonlinear acoustics of homogeneous media. This enables readers to gain insight into nonlinear wave processes in homogeneous and micro-inhomogeneous solids and compare it within the framework of the book. The subsequent eight chapters covering: Physical m
Directory of Open Access Journals (Sweden)
S. A. El-Wakil
2012-01-01
Full Text Available The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV equation for small- but finite-amplitude electrostatic ion-acoustic waves in weakly relativistic plasma consisting of warm ions and isothermal electrons. An algebraic method with computerized symbolic computation is applied in obtaining a series of exact solutions of the KdV equation. Numerical studies have been made using plasma parameters which reveal different solutions, that is, bell-shaped solitary pulses, rational pulses, and solutions with singularity at finite points, which called “blowup” solutions in addition to the propagation of an explosive pulses. The weakly relativistic effect is found to significantly change the basic properties (namely, the amplitude and the width of the ion-acoustic waves. The result of the present investigation may be applicable to some plasma environments, such as ionosphere region.
Searching for the (3+1)-Dimensional Painlevé Integrable Model and its Solitary Wave Solution
Institute of Scientific and Technical Information of China (English)
李画眉
2002-01-01
A (3+1)-dimensional integrable model constructed by conformal invariants is proven to be integrable. The solitary wave solution of the model is obtained by a simple algebraic transformation relation between the (3 + 1)-dimensional Harry-Dym equation and the cubic nonlinear Klein-Gordon equation.
Energy Technology Data Exchange (ETDEWEB)
Saha, Asit, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology, Majitar, Rangpo, East-Sikkim 737136 (India); Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India); Pal, Nikhil; Chatterjee, Prasanta, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India)
2014-10-15
The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.
Development of Surface Acoustic Wave Electronic Nose
Directory of Open Access Journals (Sweden)
S.K. Jha
2010-07-01
Full Text Available The paper proposes an effective method to design and develop surface acoustic wave (SAW sensor array-based electronic nose systems for specific target applications. The paper suggests that before undertaking full hardware development empirically through hit and trial for sensor selection, it is prudent to develop accurate sensor array simulator for generating synthetic data and optimising sensor array design and pattern recognition system. The latter aspects are most time-consuming and cost-intensive parts in the development of an electronic nose system. This is because most of the electronic sensor platforms, circuit components, and electromechanical parts are available commercially-off-the-shelve (COTS, whereas knowledge about specific polymers and data analysis software are often guarded due to commercial or strategic interests. In this study, an 11-element SAW sensor array is modelled to detect and identify trinitrotoluene (TNT and dinitrotoluene (DNT explosive vapours in the presence of toluene, benzene, di-methyl methyl phosphonate (DMMP and humidity as interferents. Additive noise sources and outliers were included in the model for data generation. The pattern recognition system consists of: (i a preprocessor based on logarithmic data scaling, dimensional autoscaling, and singular value decomposition-based denoising, (ii principal component analysis (PCA-based feature extractor, and (iii an artificial neural network (ANN classifier. The efficacy of this approach is illustrated by presenting detailed PCA analysis and classification results under varied conditions of noise and outlier, and by analysing comparative performance of four classifiers (neural network, k-nearest neighbour, naïve Bayes, and support vector machine.Defence Science Journal, 2010, 60(4, pp.364-376, DOI:http://dx.doi.org/10.14429/dsj.60.493
A Solitary Wave-Based Sensor to Monitor the Setting of Fresh Concrete
Directory of Open Access Journals (Sweden)
Piervincenzo Rizzo
2014-07-01
Full Text Available We present a proof-of-principle study about the use of a sensor for the nondestructive monitoring of strength development in hydrating concrete. The nondestructive evaluation technique is based on the propagation of highly nonlinear solitary waves (HNSWs, which are non-dispersive mechanical waves that can form and travel in highly nonlinear systems, such as one-dimensional particle chains. A built-in transducer is adopted to excite and detect the HNSWs. The waves are partially reflected at the transducer/concrete interface and partially transmitted into the concrete. The time-of-flight and the amplitude of the waves reflected at the interface are measured and analyzed with respect to the hydration time, and correlated to the initial and final set times established by the penetration test (ASTM C 403. The results show that certain features of the HNSWs change as the concrete curing progresses indicating that it has the potential of being an efficient, cost-effective tool for monitoring strengths/stiffness development.
Observation of equatorial Kelvin solitary waves in a slowly varying thermocline
Directory of Open Access Journals (Sweden)
Q. Zheng
1998-01-01
Full Text Available TOPEX/POSEIDON (T/P sea level deviation (SLD time series from 3 October 1992 to 15 May 1997 combined with upper ocean thermal structures are used to observe the characteristics and analyze the dynamics of equatorial waves in the Pacific Ocean. The evolution of the Kelvin wave propagating along an eastward shoaling thermocline in the equatorial Pacific is investigated. The behaviour of this wave as it propagates eastward can be approximately described with the solutions of the perturbed Korteweg-de Vries (PKDV equation and modified Green's Law. Assuming that the nonlinear term and dispersive term of this equation are balanced, the amplitude increases as the thermocline decreases to the power -3/8. Approaching the eastern Pacific, the nonlinearity increases and the relation changes to the power -9/8. The dispersion relation, and mass and energy conservations are investigated. The results indicate that under a varying thermocline, the nonlinear Kelvin solitary waves indeed exist in the real ocean.
Surface wave patterns on acoustically levitated viscous liquid alloys
Hong, Z. Y.; Yan, N.; Geng, D. L.; Wei, B.
2014-04-01
We demonstrate two different kinds of surface wave patterns on viscous liquid alloys, which are melted and solidified under acoustic levitation condition. These patterns are consistent with the morphologies of standing capillary waves and ensembles of oscillons, respectively. The rapid solidification of two-dimensional liquid alloy surfaces may hold them down.
INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS
Energy Technology Data Exchange (ETDEWEB)
Chou, Dean-Yi; Zhao Hui; Yang, Ming-Hsu; Liang, Zhi-Chao, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)
2012-10-20
Solar acoustic waves are scattered by a sunspot due to the interaction between the acoustic waves and the sunspot. The sunspot, excited by the incident wave, generates the scattered wave. The scattered wave is added to the incident wave to form the total wave around the sunspot. The interference fringes between the scattered wave and the incident wave are visible in the intensity of the total wave because the coherent time of the incident wave is of the order of a wave period. The strength of the interference fringes anti-correlates with the width of temporal spectra of the incident wave. The separation between neighboring fringes increases with the incident wavelength and the sunspot size. The strength of the fringes increases with the radial order n of the incident wave from n = 0 to n = 2, and then decreases from n = 2 to n = 5. The interference fringes play a role analogous to holograms in optics. This study suggests the feasibility of using the interference fringes to reconstruct the scattered wavefields of the sunspot, although the quality of the reconstructed wavefields is sensitive to the noise and errors in the interference fringes.
Non Planar Electrostatic Solitary Wave Structures in Negative Ion Degenerate Plasma
Institute of Scientific and Technical Information of China (English)
S.Hussain; N.Akhtar; Saeed-ur-Rehman
2011-01-01
@@ Theoretical and numerical studies are performed for quantum ion acoustic solitons in planar and non-planar geometries in an unmagnetized homogenous plasma consisting of warm positive and negative ions with nonthermal electrons.A deformed Korteweg de Vries(DKdV)equation is derived by using the reductive perturbation method.The numerical solution to the DKdV equation indicates that the quantum parameter, temperatures of positive ions, temperture of negative ions and electron density blatantly influence the propagation speed and the structure of quantum ion acoustic solitons.The geometrical effects on the structure of quantum ion acoustic wave are discussed.It is shown that the amplitude and propagation speed in spherical geometry is larger as compared to cylinderical and planar geometries for different values of the above-mentioned parameters.%Theoretical and numerical studies are performed for quantum ion acoustic solitons in planar and non-planar geometries in an unmagnetized homogenous plasma consisting of warm positive and negative ions with nonthermal electrons. A deformed Korteweg de Vries (DKdV) equation is derived by using the reductive perturbation method.The numerical solution to the DKdV equation indicates that the quantum parameter, temperatures of positive ions, temperture of negative ions and electron density blatantly influence the propagation speed and the structure of quantum ion acoustic solitons. The geometrical effects on the structure of quantum ion acoustic wave are discussed. It is shown that the amplitude and propagation speed in spherical geometry is larger as compared to cylinderical and planar geometries for different values of the above-mentioned parameters.
Tohya, Hirokazu; Toya, Noritaka
2014-01-01
The novel solitary electromagnetic wave (SEMW) theory and the novel design methodologies of the switching mode power supply circuit (SMPC) are presented. The SEMW theory was developed as a basic theory of the design of all kinds of the switching mode circuit including SMPC by fusing the physics of semiconductor, nonlinear undulation, and electromagnetic wave. When the SEMW theory is used, the electromagnetic analysis of SMPC becomes possible by using only the real parameters based on the phys...
Thermo-acoustic engineering of silicon microresonators via evanescent waves
Energy Technology Data Exchange (ETDEWEB)
Tabrizian, R., E-mail: rtabrizi@umich.edu [Electrical Engineering and Computer Science Department, University of Michigan, Ann Arbor, Michigan 48109 (United States); Ayazi, F. [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30308 (United States)
2015-06-29
A temperature-compensated silicon micromechanical resonator with a quadratic temperature characteristic is realized by acoustic engineering. Energy-trapped resonance modes are synthesized by acoustic coupling of propagating and evanescent extensional waves in waveguides with rectangular cross section. Highly different temperature sensitivity of propagating and evanescent waves is used to engineer the linear temperature coefficient of frequency. The resulted quadratic temperature characteristic has a well-defined turn-over temperature that can be tailored by relative energy distribution between propagating and evanescent acoustic fields. A 76 MHz prototype is implemented in single crystal silicon. Two high quality factor and closely spaced resonance modes, created from efficient energy trapping of extensional waves, are excited through thin aluminum nitride film. Having different evanescent wave constituents and energy distribution across the device, these modes show different turn over points of 67 °C and 87 °C for their quadratic temperature characteristic.
Propagation of acoustic gravity waves excited by explosions
International Nuclear Information System (INIS)
Acoustic gravity waves excited by low-altitude nuclear explosions have been observed in the ionosphere, by H.F. Doppler soundings, at horizontal distances from the source between 100 and 1200 km. The characteristics of the initial shock wave, which is observed at short range, are progressively replaced by those of the atmospheric wave guide. In particular, the dispersion properties of the signal observed in the ionosphere at long range are those of the first acoustic and gravity modes. Detailed study of the propagation times to middle and long range shows that the wave guide is mainly excited by the focalisation of acoustic energy which is produced by non-linear mechanisms at an altitude of about 100 km and at a small horizontal distance from the explosion
Thermo-acoustic engineering of silicon microresonators via evanescent waves
International Nuclear Information System (INIS)
A temperature-compensated silicon micromechanical resonator with a quadratic temperature characteristic is realized by acoustic engineering. Energy-trapped resonance modes are synthesized by acoustic coupling of propagating and evanescent extensional waves in waveguides with rectangular cross section. Highly different temperature sensitivity of propagating and evanescent waves is used to engineer the linear temperature coefficient of frequency. The resulted quadratic temperature characteristic has a well-defined turn-over temperature that can be tailored by relative energy distribution between propagating and evanescent acoustic fields. A 76 MHz prototype is implemented in single crystal silicon. Two high quality factor and closely spaced resonance modes, created from efficient energy trapping of extensional waves, are excited through thin aluminum nitride film. Having different evanescent wave constituents and energy distribution across the device, these modes show different turn over points of 67 °C and 87 °C for their quadratic temperature characteristic
Propagation of Acoustic Waves in Troposphere and Stratosphere
Kashyap, J M
2016-01-01
Acoustic waves are those waves which travel with the speed of sound through a medium. H. Lamb has derived a cutoff frequency for stratified and isothermal medium for the propagation of acoustic waves. In order to find the cutoff frequency many methods were introduced after Lamb's work. In this paper, we have chosen the method to determine cutoff frequencies for acoustic waves propagating in non-isothermal media. This turning point frequency method can be applied to various atmospheres like solar atmosphere, stellar atmosphere, earth's atmosphere etc. Here, we have analytically derived the cutoff frequency and have graphically analyzed and compared with the Lamb's cut-off frequencyfor earth's troposphere, lower and upper stratosphere.
Ionospheric signatures of acoustic waves generated by transient tropospheric forcing
Zettergren, M. D.; Snively, J. B.
2013-10-01
Acoustic waves generated by tropospheric sources may attain significant amplitudes in the thermosphere and overlying ionosphere. Although they are weak precursors to gravity waves in the mesosphere below, acoustic waves may achieve temperature and vertical wind perturbations on the order of approximately tens of Kelvin and m/s throughout the E and F regions. Their perturbations to total electron content are predicted to be detectable by ground-based radar and GPS receivers; they also drive field-aligned currents that may be detectable in situ via magnetometers. Although transient and short lived, ionospheric signatures of acoustic waves may provide new and quantitative insight into the forcing of the upper atmosphere from below.
Variational methods in nonlinear field equations solitary waves, hylomorphic solitons and vortices
Benci, Vieri
2014-01-01
The book analyzes the existence of solitons, namely of finite energy solutions of field equations which exhibit stability properties. The book is divided in two parts. In the first part, the authors give an abstract definition of solitary wave and soliton and we develop an abstract existence theory for hylomorphic solitons, namely for those solitons which minimize the energy for a given charge. In the second part, the authors apply this theory to prove the existence of hylomorphic solitons for some classes of field equations (nonlinear Klein-Gordon-Maxwell equations, nonlinear Schrödinger-Maxwell equations, nonlinear beam equation,..). The abstract theory is sufficiently flexible to be applied to other situations, like the existence of vortices. The books is addressed to Mathematicians and Physicists.
Quantum reflection of bright solitary matter-waves from a narrow attractive potential
Marchant, A L; Yu, M M H; Rakonjac, A; Helm, J L; Polo, J; Weiss, C; Gardiner, S A; Cornish, S L
2015-01-01
We report the observation of quantum reflection from a narrow, attractive, potential using bright solitary matter-waves formed from a 85Rb Bose-Einstein condensate. We create narrow potentials using a tightly focused, red-detuned laser beam, and observe reflection of up to 25% of the atoms, along with the trapping of atoms at the position of the beam. We show that the observed reflected fraction is much larger than theoretical predictions for a narrow Gaussian potential well; a more detailed model of bright soliton propagation, accounting for the generic presence of small subsidiary intensity maxima in the red-detuned beam, suggests that these small intensity maxima are the cause of this enhanced reflection.
Site-specific Quantification of Bone Quality using Highly Nonlinear Solitary Waves
Yang, Jinkyu; Borkowski, Sean; Silvestro, Claudio; De Nardo, Luigi; Daraio, Chiara; Ebramzadeh, Edward
2010-01-01
Osteoporosis is a well recognized problem affecting millions of individuals worldwide. Consequently, the need to effectively, efficiently, and affordably diagnose and identify those at risk is essential; moreover, site-specific assessment of bone quality is necessary, not only in the process of risk assessment, but may also be desirable for other applications. The present study evaluated a new one-dimensional granular crystal sensor, composed of a tightly packed chain of beads under Hertzian contact interaction, representing the most suitable fundamental component for solitary wave generation and propagation. First, the sensitivity of the novel sensor was tested using densities of rigid polyurethane foam, representing clinical bone quality ranging from healthy, to severely osteoporotic. Once the relationship between the signal response and known densities was established, the sensor was used to measure several sites located in the proximal femur of ten human cadaveric specimens. The accuracy of the model was ...
GPU acceleration of a nonhydrostatic model for the internal solitary waves simulation
Institute of Scientific and Technical Information of China (English)
CHEN Tong-qing; ZHANG Qing-he
2013-01-01
The parallel computing algorithm for a nonhydrostatic model on one or multiple Graphic Processing Units (GPUs) for the simulation of internal solitary waves is presented and discussed.The computational efficiency of the GPU scheme is analyzed by a series of numerical experiments,including an ideal case and the field scale simulations,performed on the workstation and the supercomputer system.The calculated results show that the speedup of the developed GPU-based parallel computing scheme,compared to the implementation on a single CPU core,increases with the number of computational grid cells,and the speedup can increase quasilinearly with respect to the number of involved GPUs for the problem with relatively large number of grid cells within 32 GPUs.
Broadband enhanced transmission of acoustic waves through serrated metal gratings
Qi, Dong-Xiang; Fan, Ren-Hao; Deng, Yu-Qiang; Peng, Ru-Wen; Wang, Mu; Jiangnan University Collaboration
In this talk, we present our studies on broadband properties of acoustic waves through metal gratings. We have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing and new acoustic devices. References: [1] Dong-Xiang Qi, Yu-Qiang Deng, Di-Hu Xu, Ren-Hao Fan, Ru-Wen Peng, Ze-Guo Chen, Ming-Hui Lu, X. R. Huang and Mu Wang, Appl. Phys. Lett. 106, 011906 (2015); [2] Dong-Xiang Qi, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Ming-Hui Lu, Xu Ni, Qing Hu, and Mu Wang, Applied Physics Letters 101, 061912 (2012).
Yang, Yunqing; Yan, Zhenya; Mihalache, Dumitru
2015-05-01
In this paper, we study the families of solitary-wave solutions to the inhomogeneous coupled nonlinear Schrödinger equations with space- and time-modulated coefficients and source terms. By means of the similarity reduction method and Möbius transformations, many types of novel temporal solitary-wave solutions of this nonlinear dynamical system are analytically found under some constraint conditions, such as the bright-bright, bright-dark, dark-dark, periodic-periodic, W-shaped, and rational wave solutions. In particular, we find that the localized rational-type solutions can exhibit both bright-bright and bright-dark wave profiles by choosing different families of free parameters. Moreover, we analyze the relationships among the group-velocity dispersion profiles, gain or loss distributions, external potentials, and inhomogeneous source profiles, which provide the necessary constraint conditions to control the emerging wave dynamics. Finally, a series of numerical simulations are performed to show the robustness to propagation of some of the analytically obtained solitary-wave solutions. The vast class of exact solutions of inhomogeneous coupled nonlinear Schrödinger equations with source terms might be used in the study of the soliton structures in twin-core optical fibers and two-component Bose-Einstein condensates.
Institute of Scientific and Technical Information of China (English)
Wang Feng-Jiao; Ding Jian-Wen; Yan Xiao-Hong; Wang Deng-Long
2009-01-01
Taking into account both gain/loss and time-dependent atomic scattering length, this paper analytically derives an exact bright solitary wave in a cigar-shaped attractive condensate in the presence of an expulsive parabolic potential. Due to the balance of the scattering length and gain/loss, the bright solitary wave is shown to have constant amplitude. Especially, it is found that the bright solitary wave is accelerated by expuisive force, whose velocity can be modulated by changing the axial and transverse angular frequencies. The results are in good agreement with the experimental observations by Khaykovich et al (2002 Science 296 1290).
Oblique amplitude modulation of dust-acoustic plasma waves
Kourakis, I.; Shukla, P. K.
2004-01-01
Theoretical and numerical studies are presented of the nonlinear amplitude modulation of dust-acoustic (DA) waves propagating in an unmagnetized three component, weakly-coupled, fully ionized plasma consisting of electrons, positive ions and charged dust particles, considering perturbations oblique to the carrier wave propagation direction. The stability analysis, based on a nonlinear Schroedinger-type equation (NLSE), shows that the wave may become unstable; the stability criteria depend on ...
Directory of Open Access Journals (Sweden)
Z. L. Wu
1998-01-01
Full Text Available A one-dimensional Burridge-Knopoff spring-block model with slip-dependent friction was studied to explore the possibility of a solitary wave solution existing for the problem of earthquake faulting. The result may be used as an alternative case of the crack model (e.g., Madariaga and Cochard, 1996 and the spring-block model with velocity-dependent friction (e.g., Carlson and Langer, 1989 in the understanding of the mechanism of the self-healing slip pulse proposed by Heaton (1990. In general, the conditions for a solitary wave solution to exist are discussed by the trajectory in the phase space. By taking the first order approximation, it is demonstrated that a solitary wave solution exists in which the slip behaves as a propagating solitary wave with the propagation velocity less than that of an acoustic (seismic wave, and the source time function at each position remains the same. As an alternative approach other than numerical calculations, the analytical solution, although simple, sheds light on some of the properties of the self-healing slip pulse. From the solution it is seen that the width of the pulse depends on its propagation velocity and the friction, consistent with experience in physics. It is pointed out that the self-healing slip pulse may exist for a broad class of frictional constitutive laws which, to some extent, explains the fact that the self-healing slip pulse may be observed for a variety of earthquakes occurring within different seismogenic environments.
Acoustic tweezers via sub–time-of-flight regime surface acoustic waves
Collins, David J.; Devendran, Citsabehsan; Ma, Zhichao; Ng, Jia Wei; Neild, Adrian; Ai, Ye
2016-01-01
Micrometer-scale acoustic waves are highly useful for refined optomechanical and acoustofluidic manipulation, where these fields are spatially localized along the transducer aperture but not along the acoustic propagation direction. In the case of acoustic tweezers, such a conventional acoustic standing wave results in particle and cell patterning across the entire width of a microfluidic channel, preventing selective trapping. We demonstrate the use of nanosecond-scale pulsed surface acoustic waves (SAWs) with a pulse period that is less than the time of flight between opposing transducers to generate localized time-averaged patterning regions while using conventional electrode structures. These nodal positions can be readily and arbitrarily positioned in two dimensions and within the patterning region itself through the imposition of pulse delays, frequency modulation, and phase shifts. This straightforward concept adds new spatial dimensions to which acoustic fields can be localized in SAW applications in a manner analogous to optical tweezers, including spatially selective acoustic tweezers and optical waveguides. PMID:27453940
Effects of Tidal Currents on Nonlinear Internal Solitary Waves in the South China Sea
Institute of Scientific and Technical Information of China (English)
FAN Zhisong; SHI Xingang; Antony K. Liu; LIU Hailong; LI Peiliang
2013-01-01
The propagation and fission process of intemal solitary waves (ISWs) with amplitudes of about 170m are simulated in the northeast of the South China Sea (NSCS) by using the generalized Korteweg-de Vries (KdV) equation under continuous stratification.More attention is paid to the effects of the ebb and flood background currents on the fission process of ISWs.This kind of background current is provided by the composed results simulated in terms of monthly mean baroclinic circulation and barotropic tidal current.It is found that the obtained relation of the number of fission solitons to the water depth and stratification is roughly in accordance with the fission law derived by Djordjevic and Redekopp in 1978; however,there exists obvious difference between the effects of the ebb and flood background currents on the wave-lengths of fission solitons (defined as the distance between two neighboring peaks of ISWs).The difference in nonlinearity coefficient α between the ebb and flood background currents is a main cause for the different wave-lengths of fission solitons.
Dust kinetic Alfvén solitary and rogue waves in a superthermal dusty plasma
International Nuclear Information System (INIS)
Dust kinetic Alfvén solitary waves (DKASWs) have been examined in a low-β dusty plasma comprising of negatively charged dust grains, superthermal electrons, and ions. A nonlinear Korteweg-de Vries (KdV) equation has been derived using the reductive perturbation method. The combined effects of superthermality of charged particles (via κ), plasma β, obliqueness of propagation (θ), and dust concentration (via f) on the shape and size of the DKASWs have been examined. Only negative potential (rarefactive) structures are observed. Further, characteristics of dust kinetic Alfvén rogue waves (DKARWs), by deriving the non-linear Schrödinger equation (NLSE) from the KdV equation, are studied. Rational solutions of NLSE show that rogue wave envelopes are supported by this plasma model. It is observed that the influence of various plasma parameters (superthermality, plasma β, obliqueness, and dust concentration) on the characteristics of the DKARWs is very significant. This fundamental study may be helpful in understanding the formation of coherent nonlinear structures in space and astrophysical plasma environments where superthermal particles are present
Dissipation of acoustic-gravity waves: an asymptotic approach.
Godin, Oleg A
2014-12-01
Acoustic-gravity waves in the middle and upper atmosphere and long-range propagation of infrasound are strongly affected by air viscosity and thermal conductivity. To characterize the wave dissipation, it is typical to consider idealized environments, which admit plane-wave solutions. Here, an asymptotic approach is developed that relies instead on the assumption that spatial variations of environmental parameters are gradual. It is found that realistic assumptions about the atmosphere lead to rather different predictions for wave damping than do the plane-wave solutions. A modification to the Sutherland-Bass model of infrasound absorption is proposed. PMID:25480091
High coupling materials for thin film bulk acoustic wave resonators
Conde, Janine
2009-01-01
Radio frequency (RF) filters based on bulk acoustic wave resonances in piezoelectric thin films have become indispensable components in mobile communications. The currently used material, AlN, exhibits many excellent properties for this purpose. However, its bandwidth is often a limiting factor. In addition, no tuning is possible with AlN. Ferroelectrics would offer both larger coupling to achieve larger bandwidths, and tunability. However, their acoustic properties are not well known, especi...
On acoustic wave generation in uniform shear flow
Gogoberidze, G.
2016-07-01
The linear dynamics of acoustic waves and vortices in uniform shear flow is studied. For flows with very low shear rates, the dynamics of perturbations is adiabatic and can be described by the WKB approximation. However, for flows with moderate and high shear rates the WKB approximation is not appropriate, and alternative analysis shows that two important phenomena occur: acoustic wave over-reflection and wave generation by vortices. The later phenomenon is a known linear mechanisms for sound generation in shear flows, a mechanism that is related to the continuous spectrum that arises in linear shear flow dynamics. A detailed analytical study of these phenomena is performed and the main quantitative and qualitative characteristics of the radiated acoustic field are obtained and analyzed.
Drift and ion acoustic wave driven vortices with superthermal electrons
Energy Technology Data Exchange (ETDEWEB)
Ali Shan, S. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, QAU Campus, 44000 Islamabad (Pakistan); Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad (Pakistan); Haque, Q. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, QAU Campus, 44000 Islamabad (Pakistan)
2012-08-15
Linear and nonlinear analysis of coupled drift and acoustic mode is presented in an inhomogeneous electron-ion plasma with {kappa}-distributed electrons. A linear dispersion relation is found which shows that the phase speed of both the drift wave and the ion acoustic wave decreases in the presence of superthermal electrons. Several limiting cases are also discussed. In the nonlinear regime, stationary solutions in the form of dipolar and monopolar vortices are obtained. It is shown that the condition for the boundedness of the solution implies that the speed of drift wave driven vortices reduces with increase in superthermality effect. Ignoring density inhomogeniety, it is investigated that the lower and upper limits on the speed of the ion acoustic driven vortices spread with the inclusion of high energy electrons. The importance of results with reference to space plasmas is also pointed out.
Resonance scattering of radio waves in the acoustically disturbed ionosphere
International Nuclear Information System (INIS)
It is known that acoustic waves are excited in the atmosphere for a variety of reasons, including seismic oscillations of the earth's surface as a result of earthquakes, volcanic eruptions, explosions, and in the operation of other powerful sources of natural or artificial origin. When sound waves are sufficiently intense, they can create disturbances in the electron density at ionospheric heights. In this paper, we consider the properties of radio wave scattering off such disturbances created by infrasound waves, i.e., we consider Mandel'shtam-Brillouin scattering in the ionosphere. The authors discuss the possibility of a radiophysical enhancement of the effect connected with the phenomenon of resonance scattering of the radiowaves off the disturbances created in the medium by the acoustic wave
Generation of second mode solitary waves by the interaction of a first mode soliton with a sill
Directory of Open Access Journals (Sweden)
V. I. Vlasenko
2001-01-01
Full Text Available Results of an experimental and theoretical study of the interaction of a first mode internal solitary wave with a localised bottom topography (sill are presented. Laboratory experiments have been performed in a 10m long and 0.33m wide channel filled with a stratified fluid. The interface between the two layers (fresh and salt water is diffuse and has a finite thickness. Soliton-type disturbances of the interface having characteristics of the first baroclinic mode are generated at one channel end. They move along the channel and encounter an underwater obstacle (sill in the middle of the channel, where they break into reflected and transmitted waves. Two types of internal waves are produced by the interaction: a fast first mode internal soliton and a slower (by a factor of approximately 3 second mode soliton-like wave. A numerical model, based on the two-dimensional Navier-Stokes equations in the Boussinesq approximation, is used tore produce the laboratory experiment. The detailed analysis of the horizontal and vertical structures of transmitted and reflected waves showed that the fast reflected and transmitted waves observed in the experiment can be interpreted as a first mode internal solitary wave whose characteristics are very close to those of the K-dV solitons. It is also demonstrated that the slow speed waves, generated during the interaction behind the first fast wave have vertical and horizontal structures very close to the second mode internal K-dV solitons.
A metasurface carpet cloak for electromagnetic, acoustic and water waves
Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng
2016-01-01
We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak.
A metasurface carpet cloak for electromagnetic, acoustic and water waves.
Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng
2016-01-01
We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak. PMID:26822429
Precessional magnetization switching by a surface acoustic wave
Thevenard, L.; Camara, I. S.; Majrab, S.; Bernard, M.; Rovillain, P.; Lemaître, A.; Gourdon, C.; Duquesne, J.-Y.
2016-04-01
Precessional switching allows subnanosecond and deterministic reversal of magnetic data bits. It relies on triggering a large-angle, highly nonlinear precession of magnetic moments around a bias field. Here we demonstrate that a surface acoustic wave (SAW) propagating on a magnetostrictive semiconducting material produces an efficient torque that induces precessional switching. This is evidenced by Kerr microscopy and acoustic behavior analysis in a (Ga,Mn)(As,P) thin film. Using SAWs should therefore allow remote and wave control of individual magnetic bits at potentially GHz frequencies.
An Unconditionally Stable Method for Solving the Acoustic Wave Equation
Directory of Open Access Journals (Sweden)
Zhi-Kai Fu
2015-01-01
Full Text Available An unconditionally stable method for solving the time-domain acoustic wave equation using Associated Hermit orthogonal functions is proposed. The second-order time derivatives in acoustic wave equation are expanded by these orthogonal basis functions. By applying Galerkin temporal testing procedure, the time variable can be eliminated from the calculations. The restriction of Courant-Friedrichs-Levy (CFL condition in selecting time step for analyzing thin layer can be avoided. Numerical results show the accuracy and the efficiency of the proposed method.
Revil, A.; Cathles, L. M.
2002-09-01
The Red Fault system is one of the main growth faults found in the South Eugene Island Basin, a salt withdrawal minibasin located offshore Louisiana, in the Gulf of Mexico. This fault system corresponds to a lateral boundary between fluid overpressured compartments. In addition, there is a set of observations indicating that the Red Fault system exhibits rapid episodic migration of fluids. This fault represents an example of preferential pathway for the upward episodic migration of overpressured hydrocarbons from deep, heavily pressured, compartments on time scales of years. The migrations of fluids into active growing faults could take the form of propagating surges (solitary waves) that propagate upward along the fault planes in a wave-like manner at km/yr. Solitary waves represent a very efficient mechanism for the upward transport of fluids along growth faults in sedimentary basins generating its own permeability. In addition, this mechanism is compatible with the fact that the fault plane is observed to sustain a static pore fluid pressure difference between its two sides. The propagation of solitary waves in active growth faults appears as a fundamental mechanism to understand the nature of upward fast migration of fluids along active growth faults in compartimentalized sedimentary basins.
An extreme internal solitary wave event observed in the northern South China Sea
Huang, Xiaodong; Chen, Zhaohui; Zhao, Wei; Zhang, Zhiwei; Zhou, Chun; Yang, Qingxuan; Tian, Jiwei
2016-01-01
With characteristics of large amplitude and strong current, internal solitary wave (ISW) is a major hazard to marine engineering and submarine navigation; it also has significant impacts on marine ecosystems and fishery activity. Among the world oceans, ISWs are particular active in the northern South China Sea (SCS). In this spirit, the SCS Internal Wave Experiment has been conducted since March 2010 using subsurface mooring array. Here, we report an extreme ISW captured on 4 December 2013 with a maximum amplitude of 240 m and a peak westward current velocity of 2.55 m/s. To the authors’ best knowledge, this is the strongest ISW of the world oceans on record. Full-depth measurements also revealed notable impacts of the extreme ISW on deep-ocean currents and thermal structures. Concurrent mooring measurements near Batan Island showed that the powerful semidiurnal internal tide generation in the Luzon Strait was likely responsible for the occurrence of the extreme ISW event. Based on the HYCOM data-assimilation product, we speculate that the strong stratification around Batan Island related to the strengthening Kuroshio may have contributed to the formation of the extreme ISW. PMID:27444063
An extreme internal solitary wave event observed in the northern South China Sea
Huang, Xiaodong; Chen, Zhaohui; Zhao, Wei; Zhang, Zhiwei; Zhou, Chun; Yang, Qingxuan; Tian, Jiwei
2016-07-01
With characteristics of large amplitude and strong current, internal solitary wave (ISW) is a major hazard to marine engineering and submarine navigation; it also has significant impacts on marine ecosystems and fishery activity. Among the world oceans, ISWs are particular active in the northern South China Sea (SCS). In this spirit, the SCS Internal Wave Experiment has been conducted since March 2010 using subsurface mooring array. Here, we report an extreme ISW captured on 4 December 2013 with a maximum amplitude of 240 m and a peak westward current velocity of 2.55 m/s. To the authors’ best knowledge, this is the strongest ISW of the world oceans on record. Full-depth measurements also revealed notable impacts of the extreme ISW on deep-ocean currents and thermal structures. Concurrent mooring measurements near Batan Island showed that the powerful semidiurnal internal tide generation in the Luzon Strait was likely responsible for the occurrence of the extreme ISW event. Based on the HYCOM data-assimilation product, we speculate that the strong stratification around Batan Island related to the strengthening Kuroshio may have contributed to the formation of the extreme ISW.
Directory of Open Access Journals (Sweden)
Hongwei Yang
2014-01-01
Full Text Available In the paper, by using multiple-scale method, the Benjamin-Ono-Burgers-MKdV (BO-B-MKdV equation is obtained which governs algebraic Rossby solitary waves in stratified fluids. This equation is first derived for Rossby waves. By analysis and calculation, some conservation laws are derived from the BO-B-MKdV equation without dissipation. The results show that the mass, momentum, energy, and velocity of the center of gravity of algebraic Rossby waves are conserved and the presence of a small dissipation destroys these conservations.
International Nuclear Information System (INIS)
When a point-focused acoustic lens in the scanning acoustic microscope (SAM) is faced to test specimen and defocused to some extent, two effective echoes can be obtained. One is the echo of longitudinal wave, which is normally incident upon the specimen of an on-axis beam in the central region of the lens and is reflected normal to the lens surface, hence detected by the transducer. The other is of leaky surface acoustic waves(LSAW), which are mode converted front a narrow beam of off-axis longitudinal wave, then propagate across the surface of the specimen and reradiate at angles normal to the lens surface, thus detected by the transducer. These two echoes are either interfered or separated with each other depending ell the defocused distance. It turned out theoretically that the LSAW have a narrow focal spot in the central region of the point-focused acoustic lens, whose size is approximately 40% of the LSAW wavelength. On top of that, a wavelength of LSAW is about 50% short as that of longitudinal wave. So, It is expected that high resolution images can be obtained provided LSAW are used in the scanning acoustic microscope.
Reflection and Transmission of Acoustic Waves at Semiconductor - Liquid Interface
Directory of Open Access Journals (Sweden)
J. N. Sharma
2011-09-01
Full Text Available The study of reflection and transmission characteristics of acoustic waves at the interface of a semiconductor halfspace underlying an inviscid liquid has been carried out. The reflection and transmission coefficients of reflected and transmitted waves have been obtained for quasi-longitudinal (qP wave incident at the interface from fluid to semiconductor. The numerical computations of reflection and transmission coefficients have been carried out with the help of Gauss elimination method by using MATLAB programming for silicon (Si, germanium (Ge and silicon nitride (Si3N4 semiconductors. In order to interpret and compare, the computer simulated results are plotted graphically. The study may be useful in semiconductors, seismology and surface acoustic wave (SAW devices in addition to engines of the space shuttles.
Surface spin-electron acoustic waves in magnetically ordered metals
Andreev, Pavel A
2015-01-01
Degenerate plasmas with motionless ions show existence of three surface waves: the Langmuir wave, the electromagnetic wave, and the zeroth sound. Applying the separated spin evolution quantum hydrodynamics to half-space plasma we demonstrate the existence of the surface spin-electron acoustic wave (SSEAW). We study dispersion of the SSEAW. We show that there is hybridization between the surface Langmuir wave and the SSEAW at rather small spin polarization. In the hybridization area the dispersion branches are located close to each other. In this area there is a strong interaction between these waves leading to the energy exchange. Consequently, generating the Langmuir waves with the frequencies close to hybridization area we can generate the SSEAWs. Thus, we report a method of creation of the SEAWs.
Xie, X. H.; Cuypers, Y.; Bouruet-Aubertot, P.; Pichon, A.; Lourenco, A.; Ferron, Bruno
2015-01-01
High-frequency mooring data were collected near the northern shelf edge of the Bay of Biscay to investigate the generation and propagation of internal tides and internal solitary waves (ISWs). During spring tide, strong nonlinear internal tides and large amplitude ISWs are observed every semidiurnal tidal period. While onshore propagation was expected since the mooring is located shoreward of the maximum internal tidal generation location, both onshore and seaward traveling internal tides are...
Discrete doubly periodic and solitary wave solutions for the semi-discrete coupled mKdV equations
Institute of Scientific and Technical Information of China (English)
Wu Xiao-Fei; Zhu Jia-Min; Ma Zheng-Yi
2007-01-01
In this paper, the improved Jacobian elliptic function expansion approach is extended and applied to constructing discrete solutions of the semi-discrete coupled modified Korteweg de Vries (mKdV) equations with the aid of the symbolic computation system Maple. Some new discrete Jacobian doubly periodic solutions are obtained. When the modulus M → 1, these doubly periodic solutions degenerate into the corresponding solitary wave solutions, including kink-type, bell-type and other types of excitations.
Institute of Scientific and Technical Information of China (English)
ZHANG Shan-wu; FAN Zhi-song
2013-01-01
A variable coefficient,rotation-modified extended Kortweg-deVries (vReKdV) model is applied to the study of the South China Sea (SCS),with focus on the effects of the high-order (cubic) nonlinearity and the rotation on the disintegration process of large-amplitude (170 m) Internal Solitary Waves (ISWs) and the semi-diurnal internal tide propagating from the deep basin station to the slope and shelf regions in a continuously stratified system.The numerical solutions show that the high-order nonlinearity significantly affects the wave profile by increasing the wave amplitude and the phase speed in the simulated area.It is shown that the initial KdV-type ISW will decay faster when the rotation dispersion is considered,however the wave profile does not change significantly and the rotation effect is not important.The simulations of the semi-diumal intemaI tide indicate that the phase of the wave profile is shifted earlier when the rotation effect is included.A solitary wave packet emerges on the shelf,and the wave speed is also greater when considering the rotation dispersion.In addition,the effects of the background currents are discussed further in this paper.It is found that the background currents generally change the magnitude and occasionally change the sign of the nonlinear coefficients in the northern SCS.
Sayyar, M.; Zahed, H.; Pestehe, S. J.; Sobhanian, S.
2016-07-01
Using the Sagdeev pseudo-potential method, the oblique propagation of dust-ion acoustic solitary waves is studied in a magnetized dusty plasma. By considering non-thermal distribution of electrons, the related pseudo-potential is obtained using the Poisson equation. The behavior of the wave is investigated for some ranges of parameters. It is demonstrated that the increase in ion density, lz, β, and also δ1 can lead to the increases in the width and amplitude of the pseudo-potential, while any increase of a2, the coefficient that describes the first nonlinear term in the G ( ϕ ) , increases the amplitude of the V ( ϕ ) .
Energy Technology Data Exchange (ETDEWEB)
El-Hanbaly, A. M.; Sallah, M., E-mail: msallahd@mans.edu.eg [Mansoura University, Physics Department, Faculty of Science (Egypt); El-Shewy, E. K. [Taibah University Al-Madinah Al-Munawarah, Department of Physics (Saudi Arabia); Darweesh, H. F. [Mansoura University, Physics Department, Faculty of Science (Egypt)
2015-10-15
Linear and nonlinear dust-acoustic (DA) waves are studied in a collisionless, unmagnetized and dissipative dusty plasma consisting of negatively charged dust grains, Boltzmann-distributed electrons, and nonthermal ions. The normal mode analysis is used to obtain a linear dispersion relation illustrating the dependence of the wave damping rate on the carrier wave number, the dust viscosity coefficient, the ratio of the ion temperature to the electron temperatures, and the nonthermal parameter. The plasma system is analyzed nonlinearly via the reductive perturbation method that gives the KdV-Burgers equation. Some interesting physical solutions are obtained to study the nonlinear waves. These solutions are related to soliton, a combination between a shock and a soliton, and monotonic and oscillatory shock waves. Their behaviors are illustrated and shown graphically. The characteristics of the DA solitary and shock waves are significantly modified by the presence of nonthermal (fast) ions, the ratio of the ion temperature to the electron temperature, and the dust kinematic viscosity. The topology of the phase portrait and the potential diagram of the KdV-Burgers equation is illustrated, whose advantage is the ability to predict different classes of traveling wave solutions according to different phase orbits. The energy of the soliton wave and the electric field are calculated. The results in this paper can be generalized to analyze the nature of plasma waves in both space and laboratory plasma systems.
International Nuclear Information System (INIS)
Linear and nonlinear dust-acoustic (DA) waves are studied in a collisionless, unmagnetized and dissipative dusty plasma consisting of negatively charged dust grains, Boltzmann-distributed electrons, and nonthermal ions. The normal mode analysis is used to obtain a linear dispersion relation illustrating the dependence of the wave damping rate on the carrier wave number, the dust viscosity coefficient, the ratio of the ion temperature to the electron temperatures, and the nonthermal parameter. The plasma system is analyzed nonlinearly via the reductive perturbation method that gives the KdV-Burgers equation. Some interesting physical solutions are obtained to study the nonlinear waves. These solutions are related to soliton, a combination between a shock and a soliton, and monotonic and oscillatory shock waves. Their behaviors are illustrated and shown graphically. The characteristics of the DA solitary and shock waves are significantly modified by the presence of nonthermal (fast) ions, the ratio of the ion temperature to the electron temperature, and the dust kinematic viscosity. The topology of the phase portrait and the potential diagram of the KdV-Burgers equation is illustrated, whose advantage is the ability to predict different classes of traveling wave solutions according to different phase orbits. The energy of the soliton wave and the electric field are calculated. The results in this paper can be generalized to analyze the nature of plasma waves in both space and laboratory plasma systems
Directory of Open Access Journals (Sweden)
Jia Lin Wu
2013-06-01
Full Text Available In macromolecular self-avoiding random walk, movement of each chain-particle accompanies an instantaneous spin system with de Gennes n = 0 that provides extra energy, extra vacancy volume and relaxation time needed for chain-particles co-movement. Using these additional and instantaneous spin systems not only directly yields the same Brownian motion mode in glass transition (GT and reptation-tube model, but also proves that the entangled chain length corresponding to the Reynolds number in hydrodynamics and the inherent diffusion - delocalization mode of entangled chains, from frozen glass state to melt liquid state, is a chain-size solitary wave with transverse ripplon-like soft wave. Thus, the order parameter of GT is found. The various currently available GT theories, such as Static Replica, Random First-Order Transition, Potential Energy Landscape, Mode-Coupling and Nanoscale Heterogeneity, can be unified using the additional and instantaneous spin system. GT served as an inspiration and continues to serve as the paradigm in the universal random delocalization transitions from disorder to more disorder until turbulence.
Numerical modelling of nonlinear full-wave acoustic propagation
International Nuclear Information System (INIS)
The various model equations of nonlinear acoustics are arrived at by making assumptions which permit the observation of the interaction with propagation of either single or joint effects. We present here a form of the conservation equations of fluid dynamics which are deduced using slightly less restrictive hypothesis than those necessary to obtain the well known Westervelt equation. This formulation accounts for full wave diffraction, nonlinearity, and thermoviscous dissipative effects. A two-dimensional, finite-volume method using Roe’s linearisation has been implemented to obtain numerically the solution of the proposed equations. This code, which has been written for parallel execution on a GPU, can be used to describe moderate nonlinear phenomena, at low Mach numbers, in domains as large as 100 wave lengths. Applications range from models of diagnostic and therapeutic HIFU, to parametric acoustic arrays and nonlinear propagation in acoustic waveguides. Examples related to these applications are shown and discussed
Numerical modelling of nonlinear full-wave acoustic propagation
Energy Technology Data Exchange (ETDEWEB)
Velasco-Segura, Roberto, E-mail: roberto.velasco@ccadet.unam.mx; Rendón, Pablo L., E-mail: pablo.rendon@ccadet.unam.mx [Grupo de Acústica y Vibraciones, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Ciudad Universitaria, Apartado Postal 70-186, C.P. 04510, México D.F., México (Mexico)
2015-10-28
The various model equations of nonlinear acoustics are arrived at by making assumptions which permit the observation of the interaction with propagation of either single or joint effects. We present here a form of the conservation equations of fluid dynamics which are deduced using slightly less restrictive hypothesis than those necessary to obtain the well known Westervelt equation. This formulation accounts for full wave diffraction, nonlinearity, and thermoviscous dissipative effects. A two-dimensional, finite-volume method using Roe’s linearisation has been implemented to obtain numerically the solution of the proposed equations. This code, which has been written for parallel execution on a GPU, can be used to describe moderate nonlinear phenomena, at low Mach numbers, in domains as large as 100 wave lengths. Applications range from models of diagnostic and therapeutic HIFU, to parametric acoustic arrays and nonlinear propagation in acoustic waveguides. Examples related to these applications are shown and discussed.
Acoustic nonlinearity of ultrasonic wave by crack face contacting effect
International Nuclear Information System (INIS)
Nonlinear acoustic effect accompanied by the propagation of ultrasonic wave has been discussed from log time before and the effort to evaluate material degradation or degree of damage by measuring this effect has been tried in recent. The mechanism for the generation of nonlinear acoustic effect was proposed by several researchers and these previous studies have identified two primary sources of the nonlinearity. One source is the anharmonicity of lattice itself. The other source is associated with the contribution of dislocation displacement. In this paper, an another new source of nonlinearity generated due to the partial contact of crack face when the ultrasonic wave passes through tiny crack is considered. At first, the mechanism of the generation of acoustic nonlinearity at the crack face by half wave model was explained and the relationship between the separation distance of crack faces and. the magnitude of nonlinearity was investigated quantitatively by fourier transform of the half wave and computer simulation. In next, the existence of the proposed new source of nonlinearity at crack face was shown experimentally in the actual case, SAM signal obtained for the Newton ring. From the result, we confirmed that the crack face contacting effect should be considered as a additive source of acoustic nonlinearity when we apply the ultrasonic nonlinearity analysis to the evaluation of material degradation.
Monolithic ZnO SAW (Surface Acoustic Waves) structures
Gunshor, R. L.; Pierret, R. F.
1983-07-01
ZnO-on-silicon surface acoustic wave devices have been fabricated and tested. Electronic erasure of a stored correlator reference was demonstrated, the effect of laser annealing on propagation loss was examined, preliminary ageing studies were performed, and a conceptually new mode conversion resonator configuration was reported.
Ion Acoustic Waves in the Presence of Langmuir Oscillations
DEFF Research Database (Denmark)
Pécseli, Hans
1976-01-01
The dielectric function for long-wavelength, low-frequency ion acoustic waves in the presence of short-wavelength, high-frequency electron oscillations is presented, where the ions are described by the collision-free Vlasov equation. The effect of the electron oscillations can be appropriately...
Gasoline identifier based on SH0 plate acoustic waves.
Kuznetsova, Iren E; Zaitsev, Boris D; Seleznev, Eugenii P; Verona, Enrico
2016-08-01
The present paper is devoted to the development of gasoline identifier based on zero order shear-horizontal (SH0) acoustic wave propagating in piezoelectric plate. It has been found that the permittivity of gasoline is increased when its octane number rises. The development of such identifier is experimentally demonstrated to be possible. PMID:27125559
Enhancing Plasma Surface Modification using high Intensity and high Power Ultrasonic Acoustic Waves
DEFF Research Database (Denmark)
2010-01-01
high intensity and high power acoustic waves (102) by at least one ultrasonic high intensity and high power acoustic wave generator (101 ), wherein the ultrasonic acoustic waves are directed to propagate towards said surface (314) of the object (100) so that a laminar boundary layer (313) of a gas or a...
Liu, Chuangye; Nguyen, Nghiem V.; Wang, Zhi-Qiang
2016-10-01
In this paper, we investigate the orbital stability of solitary-wave solutions for an m-coupled nonlinear Schrödinger system i /∂ ∂ t u j + /∂ 2 ∂ x 2 u j + ∑ i = 1 m b i j |" separators=" u i | 2 u j = 0 , j = 1 , … , m , where m ≥ 2, uj are complex-valued functions of (x, t) ∈ ℝ2, bjj ∈ ℝ, j = 1, 2, …, m, and bij, i ≠ j are positive coupling constants satisfying bij = bji. It will be shown that spatially synchronized solitary-wave solutions of the m-coupled nonlinear Schrödinger system exist and are orbitally stable. Here, by synchronized solutions we mean solutions in which the components are proportional to one another. Our results completely settle the question on the existence and stability of synchronized solitary waves for the m-coupled system while only partial results were known in the literature for the cases of m ≥ 3 heretofore. Furthermore, the conditions imposed on the symmetric matrix B = (bij) satisfied here are both sufficient and necessary for the m-coupled nonlinear Schrödinger system to admit synchronized ground-state solutions.
Propagation-invariant waves in acoustic, optical, and radio-wave fields
Salo, Janne
2003-01-01
The physical phenomena considered in this thesis are associated with electromagnetic and acoustic waves that propagate in free space or in homogeneous media without diffraction. The concept of rotationally periodic wave propagation is introduced in the first journal article included in the thesis and it is subsequently used to analyse waves that avoid diffractive deterioration by repeatedly returning to their initial shape, possibly rotated around the optical axis. Such waves constitute an es...
Indian Academy of Sciences (India)
M Singh; P N Deka
2006-03-01
A theoretical study is made on the generation mechanism of ion acoustics wave in the presence of lower hybrid wave turbulence field in inhomogeneous plasma on the basis of plasma-maser interaction. The lower hybrid wave turbulence field is taken as the low-frequency turbulence field. The growth rate of test high frequency ion acoustics wave is obtained with the involvement of spatial density gradient parameter. A comparative study of the role of density gradient for the generation of ion acoustics wave on the basis of plasma-maser effect is presented. It is found that the density gradient influences the growth rate of ion acoustics wave.
Surface acoustic wave mode conversion resonator
Martin, S. J.; Gunshor, R. L.; Melloch, M. R.; Datta, S.; Pierret, R. F.
1983-08-01
The fact that a ZnO-on-Si structure supports two distinct surface waves, referred to as the Rayleigh and the Sezawa modes, if the ZnO layer is sufficiently thick is recalled. A description is given of a unique surface wave resonator that operates by efficiently converting between the two modes at the resonant frequency. Since input and output coupling is effected through different modes, the mode conversion resonator promises enhanced out-of-band signal rejection. A Rayleigh wave traversing the resonant cavity in one direction is reflected as a Sezawa wave. It is pointed out that the off-resonance rejection of the mode conversion resonator could be enhanced by designing the transducers to minimize the level of cross coupling between transducers and propagating modes.
On the generation and propagation of internal solitary waves in the southern Bay of Biscay
Azevedo, A.; da Silva, J. C. B.; New, A. L.
2006-06-01
Internal solitary waves (ISWs), travelling towards the South-South-West (SSW), are now well documented in the northern and central Bay of Biscay. These are formed from large-amplitude internal tides which result from the interaction of the barotropic tide with the steep shelf-break topography. In the present paper, we investigate available satellite imagery (Synthetic Aperture Radar (SAR) and ASAR data) to reveal that the southern Bay of Biscay is also a "hotspot" region which has a high level of ISW activity. Here, the ISWs travel towards the East-North-East from the Cape Finisterre region off North-West Spain. In fact, we reveal the presence of two wave-trains travelling in slightly different directions (055°T and 040°T). By calculating the strength of the barotropic tidal forcing in the region, and identifying the likely propagation pathways (rays) of internal tidal (IT) energy, we identify the generation sites for these wave-trains as lying on either side of the Ortegal Promontory (OP). This is an undersea "headland" projecting towards the North-West from the north-western coast of Spain (near 44°N, 8.5°W), and over which the barotropic tides are forced to flow. For each generation site, IT rays emanating from "critical" topography (where the ray slope is equal to the topographic slope) in regions of strong barotropic forcing, rise to the surface (for one site after a reflection from the sea-floor) and pass through the thermocline close to the earliest occurrences of the ISWs in the respective wave trains. These rays would then produce, through nonlinear processes, the ISWs through the same "local generation" mechanism that has been used to explain the occurrence of the ISWs in the northern and central Bay. The "local generation" mechanism may therefore be more widely applicable than previously thought. In addition, the methods we have used to deduce the generation sites for these waves are expected to prove equally useful for studies in other areas of the
Monthly variation of some parameters about internal solitary waves in the South China sea
Cai, Shuqun; Xie, Jieshuo; Xu, Jiexin; Wang, Dongxiao; Chen, Zhiwu; Deng, Xiaodong; Long, Xiaomin
2014-02-01
In this paper, by non-dimensional analysis, it is found that finite-depth theory is more appropriate to the study of internal solitary waves (ISWs) in the South China Sea (SCS) than shallow-water theory. The 1-degree grid data of monthly mean temperature and salinity data at standard levels in the SCS are used to solve the linearized vertical eigenvalue problem. The nonlinear parameter and the wave phase speed are computed, then the nonlinear phase speed and the characteristic half-width of ISWs are calculated respectively by two different theories to investigate the difference between these two parameters in the SCS. The nonlinearity is the strongest near the continental slope of the SCS or islands where the bottom topography changes sharply, it is stronger in summer than that in winter; it increases (decreases) as pycnocline depth deepens (shallows), stratification strengthens (weakens) and pycnocline thickness thins (thickens). The nonlinear wave phase speed and the characteristic half-width are the largest in deep sea area, they then reduce peripherally in shallower water. The nonlinear wave phase speed in the SCS changes slightly with time, but the characteristic half-width changes somewhat larger with time. In most of the SCS basin, the nonlinear wave phase speed derived from shallow-water theory is very close to that derived from finite-depth theory, but the characteristic half-width derived from shallow-water theory is about 0.2-0.6 times larger than that derived from finite-depth theory. The ISW induced horizontal current velocity derived from shallow-water theory is larger than that derived from finite-depth theory. Some observed and numerical modeled ISW characteristic half-widths are compared with those derived from shallow-water and finite-depth theories, respectively. It is shown that, the characteristic half-widths derived from finite-depth theory agree better with observational and numerical modeled results than those derived from shallow
Electron-Acoustic Compressive Soliton and Electron Density Hole in Aurora
Institute of Scientific and Technical Information of China (English)
王德焴
2003-01-01
Electron-acoustic solitary waves have been studied in an electron-beam plasma system. It is found that the solution of compressive soliton only exists within a limited range of soliton velocity around the electron beam velocity. A compressive electron-acoustic soliton always accompanies with a cold electron density hole. This theoretical model is used to explain the ‘fast solitary wave' event observed by the FAST satellite in the midaltitude auroral zone.
Influence of Ion Nonlinear Polarization Drift and Warm Ions on Solitary Kinetic Alfven Wave
Institute of Scientific and Technical Information of China (English)
DUANSu-Ping; LIZhong-Yuan
2003-01-01
Considering the effects of ion nonlinear polarization drift and warm ions, we adopt two-fluid model to investigate the character of low-frequency Solitary Kinetic Alfven Wave (SKAW hereafter) in a magnetic plasma. The results derived in this paper indicate that dip SKAW and hump SKAW both exist in a wide range in magnetosphere (for the pressure parameter β-10-5 -0.01, where β is the ratio of thermal pressure to magnetic pressure, i.e.β=2μonT/B02 ). These two kinds of SKAWs propagate at either Super-Alfvenic velocity or Sub-Alfvenic velocity. In the inertial region β>β>>me/mi. These results are different from previous ones. That indicates that the effects of ion nonlinear polarization drift and warm ions are important and they cannot be neglected. The SKAW has an electric field parallel to the ambient magnetic field, which makes the SKAW take an important role in the acceleration and energization of field-aligned charged particles in magnetic plasmas. And the SKAW is also important for the heating of a local plasma.So it makes a novel physical mechanism of energy transmission possible.
da Silva, Jose C. B.; Grimshaw, Roger H. J.; Magalhaes, Jorge M.
2010-05-01
A recent study revealed that Race Point Channel (in Cape Cod, Massachusetts) is a hotspot of internal solitary wave generation. SAR images suggest that the waves are generated within the channel (which has a flat bottom) during the ebb phase of the tide (flowing offshore) and propagate upstream during the initial stages of their formation. Some of these waves propagate into Massachusetts Bay (further North) and interact with the well known Stellwagen Bank internal waves that are generated on the lee-side of the Bank. The southern flank of Stellwagen Bank has very sharp bathymetric gradients and can be considered as a vertical step. Here we discuss the results of analysis of 25 TerraSAR-X radar images (in very high spatial resolution, 3 meters) and a collection of ENVISAT/ERS tandem mission acquisitions (separated in time by approximately 30 minutes) that reveal details about internal wave reflection at the southern flank of Stellwagen Bank. The SAR data also show transmission of internal waves over the Bank and subsequent interaction with lee-waves generated at the eastern side of Stellwagen Bank. The radar backscatter profiles are compared with theory of the transformation of a weakly nonlinear interfacial solitary wave in a two-layer model over a step. The coefficients of wave reflection and transmission are calculated based on typical stratification of the region and assuming linear theory of long interfacial waves. In addition, collision of reflected waves from the Bank with internal waves generated at the Race Point channel (one tidal cycle after) has been occasionally observed. The radar backscatter profiles suggest that the total wave amplitude during the interaction is greater than that obtained by simply adding the individual solitary wave amplitudes, which is in agreement with the theory of obliquely interacting solitary waves at a near critical angle (150°). This may imply localized turbulent mixing as a result of internal solitary wave interaction at
El-Labany, S. K.; El-Taibany, W. F.; Behery, E. E.; Zedan, N. A.
2015-12-01
Propagation of dust acoustic solitary waves (DASWs) in a magnetized dusty plasma consisting of extremely massive, negatively/positively charged dust fluid and Boltzmann distributed electrons and ions is studied. A nonlinear Zakharov-Kuznetsov (ZK) equation adequate for describing the solitary waves is derived by applying a reductive perturbation technique. Moreover, an extended Zakharov Kuznetsov (EZK) equation is derived at the vicinity of the critical phase velocity. The effects of the polarization force are explicitly discussed and the growth rate of the produced waves is calculated. It is found that the physical parameters have strong effects on the instability criterion as well as on the growth rate. It is noted that the phase velocity decreases as the polarization force, the effective-to-ion temperature ratio, and the ion-to-electron temperature ratio increase. Moreover, the nonlinearity coefficient and the critical phase velocity increase by increasing the polarization force. The relevance of these findings to a recent plasma experiment and astrophysical plasma observations is briefly discussed.
Synchronization of self-excited dust acoustic waves
Suranga Ruhunusiri, W. D.; Goree, John
2012-10-01
Synchronization is a nonlinear phenomenon where a self-excited oscillation, like a wave in a plasma, interacts with an external driving, resulting in an adjustment of the oscillation frequency. Dust acoustic wave synchronization has been experimentally studied previously in laboratory and in microgravity conditions, e.g. [Pilch PoP 2009] and [Menzel PRL 2010]. We perform a laboratory experiment to study synchronization of self-excited dust acoustic waves. An rf glow discharge argon plasma is formed by applying a low power radio frequency voltage to a lower electrode. A 3D dust cloud is formed by levitating 4.83 micron microspheres inside a glass box placed on the lower electrode. Dust acoustic waves are self-excited with a natural frequency of 22 Hz due to an ion streaming instability. A cross section of the dust cloud is illuminated by a vertical laser sheet and imaged from the side with a digital camera. To synchronize the waves, we sinusoidally modulate the overall ion density. Differently from previous experiments, we use a driving electrode that is separate from the electrode that sustains the plasma, and we characterize synchronization by varying both driving amplitude and frequency.
Solitary Waves under the Influence of a Long-Wave Mode
Riecke, H
1995-01-01
The dynamics of solitons of the nonlinear Schrödinger equation under the influence of dissipative and dispersive perturbations is investigated. In particular a coupling to a long-wave mode is considered using extended Ginzburg-Landau equations. The study is motivated by the experimental observation of localized wave trains (`pulses') in binary-liquid convection. These pulses have been found to drift exceedingly slowly. The perturbation analysis reveals two distinct mechanisms which can lead to a `trapping' of the pulses by the long-wave concentration mode. The are given by the effect of the concentration mode on the local growth rate and on the frequency of the wave. The latter, dispersive mechanism has not been recognized previously, despite the fact that it dominates over the dissipative contribution within the perturbation theory. A second unexpected result is that the pulse can be accelerated by the concentration mode despite the reduced growth rate ahead of the pulse. The dependence of the pulse velocit...
Optimization of Surface Acoustic Wave-Based Rate Sensors
Directory of Open Access Journals (Sweden)
Fangqian Xu
2015-10-01
Full Text Available The optimization of an surface acoustic wave (SAW-based rate sensor incorporating metallic dot arrays was performed by using the approach of partial-wave analysis in layered media. The optimal sensor chip designs, including the material choice of piezoelectric crystals and metallic dots, dot thickness, and sensor operation frequency were determined theoretically. The theoretical predictions were confirmed experimentally by using the developed SAW sensor composed of differential delay line-oscillators and a metallic dot array deposited along the acoustic wave propagation path of the SAW delay lines. A significant improvement in sensor sensitivity was achieved in the case of 128° YX LiNbO3, and a thicker Au dot array, and low operation frequency were used to structure the sensor.
Langasite Surface Acoustic Wave Sensors: Fabrication and Testing
Energy Technology Data Exchange (ETDEWEB)
Zheng, Peng; Greve, David W.; Oppenheim, Irving J.; Chin, Tao-Lun; Malone, Vanessa
2012-02-01
We report on the development of harsh-environment surface acoustic wave sensors for wired and wireless operation. Surface acoustic wave devices with an interdigitated transducer emitter and multiple reflectors were fabricated on langasite substrates. Both wired and wireless temperature sensing was demonstrated using radar-mode (pulse) detection. Temperature resolution of better than ±0.5°C was achieved between 200°C and 600°C. Oxygen sensing was achieved by depositing a layer of ZnO on the propagation path. Although the ZnO layer caused additional attenuation of the surface wave, oxygen sensing was accomplished at temperatures up to 700°C. The results indicate that langasite SAW devices are a potential solution for harsh-environment gas and temperature sensing.
Chromospheric heating by acoustic waves compared to radiative cooling
Sobotka, M; Švanda, M; Jurčák, J; del Moro, D; Berrilli, F
2016-01-01
Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of solar atmosphere. A weak chromospheric plage near a large solar pore NOAA 11005 was observed on October 15, 2008 in the lines Fe I 617.3 nm and Ca II 853.2 nm with the Interferometric Bidimemsional Spectrometer (IBIS) attached to the Dunn Solar Telescope. Analyzing the Ca II observations with spatial and temporal resolutions of 0.4" and 52 s, the energy deposited by acoustic waves is compared with that released by radiative losses. The deposited acoustic flux is estimated from power spectra of Doppler oscillations measured in the Ca II line core. The radiative losses are calculated using a grid of seven 1D hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 72 %. In quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only of about 15 %. In active areas with photospheric ma...
Institute of Scientific and Technical Information of China (English)
YAN ZhenYa; XIE FuDing; ZHANG HongQing
2001-01-01
Both the direct method due to Clarkson and Kruskal and the improved direct method due to Lou are extended to reduce the high-order modified Boussinesq equation with the damping term (HMBEDT) arising in the general Fermi-Pasta-Ulam model. As a result, several types of similarity reductions are obtained. It is easy to show that the nonlinear wave equation is not integrable under the sense of AblowRz's conjecture from the reduction results obtained. In addition, kink-shaped solitary wave solutions, which are of important physical significance, are found for HMBEDT based on the obtained reduction equation.``
Seismic wave imaging in visco-acoustic media
Institute of Scientific and Technical Information of China (English)
WANG Huazhong; ZHANG Libin; MA Zaitian
2004-01-01
Realistic representation of the earth may be achieved by combining the mechanical properties of elastic solids and viscousliquids. That is to say, the amplitude will be attenuated withdifferent frequency and the phase will be changed in the seismicdata acquisition. In the seismic data processing, this effect mustbe compensated. In this paper, we put forward a visco-acoustic wavepropagator which is of better calculating stability and tolerablecalculating cost (little more than an acoustic wave propagator).The quite good compensation effect is demonstrated by thenumerical test results with synthetic seismic data and real data.
Indian Academy of Sciences (India)
Jalil Manafian; Mehrdad Lakestani
2015-07-01
An application of the (′/)-expansion method to search for exact solutions of nonlinear partial differential equations is analysed. This method is used for Burgers, Fisher, Huxley equations and combined forms of these equations. The (′/)-expansion method was used to construct periodic wave and solitary wave solutions of nonlinear evolution equations. This method is developed for searching exact travelling wave solutions of nonlinear partial differential equations. It is shown that the (′/)-expansion method, with the help of symbolic computation, provides a straightforward and powerful mathematical tool for solving nonlinear partial differential equations.
Tuneable film bulk acoustic wave resonators
Gevorgian, Spartak Sh; Vorobiev, Andrei K
2013-01-01
To handle many standards and ever increasing bandwidth requirements, large number of filters and switches are used in transceivers of modern wireless communications systems. It makes the cost, performance, form factor, and power consumption of these systems, including cellular phones, critical issues. At present, the fixed frequency filter banks based on Film Bulk Acoustic Resonators (FBAR) are regarded as one of the most promising technologies to address performance -form factor-cost issues. Even though the FBARs improve the overall performances the complexity of these systems remains high. Attempts are being made to exclude some of the filters by bringing the digital signal processing (including channel selection) as close to the antennas as possible. However handling the increased interference levels is unrealistic for low-cost battery operated radios. Replacing fixed frequency filter banks by one tuneable filter is the most desired and widely considered scenario. As an example, development of the softwa...
Making structured metals transparent for ultrabroadband electromagnetic waves and acoustic waves
Energy Technology Data Exchange (ETDEWEB)
Fan, Ren-Hao [National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Peng, Ru-Wen, E-mail: rwpeng@nju.edu.cn [National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Huang, Xian-Rong [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Wang, Mu [National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)
2015-07-15
In this review, we present our recent work on making structured metals transparent for broadband electromagnetic waves and acoustic waves via excitation of surface waves. First, we theoretically show that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic waves by relying on surface plasmons or spoof surface plasmons. Second, we experimentally demonstrate that metallic gratings with narrow slits are highly transparent for broadband terahertz waves at oblique incidence and high transmission efficiency is insensitive to the metal thickness. Further, we significantly develop oblique metal gratings transparent for broadband electromagnetic waves (including optical waves and terahertz ones) under normal incidence. In the third, we find the principles of broadband transparency for structured metals can be extended from one-dimensional metallic gratings to two-dimensional cases. Moreover, similar phenomena are found in sonic artificially metallic structures, which present the transparency for broadband acoustic waves. These investigations provide guidelines to develop many novel materials and devices, such as transparent conducting panels, antireflective solar cells, and other broadband metamaterials and stealth technologies. - Highlights: • Making structured metals transparent for ultrabroadband electromagnetic waves. • Non-resonant excitation of surface plasmons or spoof surface plasmons. • Sonic artificially metallic structures transparent for broadband acoustic waves.
SILICON COMPATIBLE ACOUSTIC WAVE RESONATORS: DESIGN, FABRICATION AND PERFORMANCE
Directory of Open Access Journals (Sweden)
Aliza Aini Md Ralib
2014-12-01
Full Text Available ABSTRACT: Continuous advancement in wireless technology and silicon microfabrication has fueled exciting growth in wireless products. The bulky size of discrete vibrating mechanical devices such as quartz crystals and surface acoustic wave resonators impedes the ultimate miniaturization of single-chip transceivers. Fabrication of acoustic wave resonators on silicon allows complete integration of a resonator with its accompanying circuitry. Integration leads to enhanced performance, better functionality with reduced cost at large volume production. This paper compiles the state-of-the-art technology of silicon compatible acoustic resonators, which can be integrated with interface circuitry. Typical acoustic wave resonators are surface acoustic wave (SAW and bulk acoustic wave (BAW resonators. Performance of the resonator is measured in terms of quality factor, resonance frequency and insertion loss. Selection of appropriate piezoelectric material is significant to ensure sufficient electromechanical coupling coefficient is produced to reduce the insertion loss. The insulating passive SiO2 layer acts as a low loss material and aims to increase the quality factor and temperature stability of the design. The integration technique also is influenced by the fabrication process and packaging. Packageless structure using AlN as the additional isolation layer is proposed to protect the SAW device from the environment for high reliability. Advancement in miniaturization technology of silicon compatible acoustic wave resonators to realize a single chip transceiver system is still needed. ABSTRAK: Kemajuan yang berterusan dalam teknologi tanpa wayar dan silikon telah menguatkan pertumbuhan yang menarik dalam produk tanpa wayar. Saiz yang besar bagi peralatan mekanikal bergetar seperti kristal kuarza menghalang pengecilan untuk merealisasikan peranti cip. Silikon serasi gelombang akustik resonator mempunyai potensi yang besar untuk menggantikan unsur
Effect of Bohm quantum potential in the propagation of ion-acoustic waves in degenerate plasmas
Hasan, M. M.; Hossen, M. A.; Rafat, A.; Mamun, A. A.
2016-10-01
A theoretical investigation has been carried out on the propagation of the ion-acoustic (IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of inertial non-relativistic light ion fluid. The Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and mixed mK-dV (mmK-dV) equations are derived by adopting the reductive perturbation method. In order to analyze the basic features (phase speed, amplitude, width, etc.) of the IA solitary waves (SWs), the SWs solutions of the K-dV, mK-dV, and mmK-dV are numerically analyzed. It is found that the degenerate pressure, inclusion of the new phenomena like the Fermi temperatures and quantum mechanical effects (arising due to the quantum diffraction) of both electrons and positrons, number densities, etc., of the plasma species remarkably change the basic characteristics of the IA SWs which are found to be formed either with positive or negative potential. The implication of our results in explaining different nonlinear phenomena in astrophysical compact objects, e.g., white dwarfs, neutron stars, etc., and laboratory plasmas like intense laser-solid matter interaction experiments, etc., are mentioned.
Superresolution through the topological shaping of sound with an acoustic vortex wave antenna
Guild, Matthew D; Martin, Theodore P; Rohde, Charles A; Orris, Gregory J
2016-01-01
In this paper, we demonstrate far-field acoustic superresolution using shaped acoustic vortices. Compared with previously proposed near-field methods of acoustic superresolution, in this work we describe how far-field superresolution can be obtained using an acoustic vortex wave antenna. This is accomplished by leveraging the recent advances in optical vortices in conjunction with the topological diversity of a leaky wave antenna design. In particular, the use of an acoustic vortex wave antenna eliminates the need for a complicated phased array consisting of multiple active elements, and enables a superresolving aperture to be achieved with a single simple acoustic source and total aperture size less than a wavelength in diameter. A theoretical formulation is presented for the design of an acoustic vortex wave antenna with arbitrary planar arrangement, and explicit expressions are developed for the radiated acoustic pressure field. This geometric versatility enables variously-shaped acoustic vortex patterns t...
Lay, E. H.; Shao, X. M.; Kendrick, A.
2014-12-01
Gravity waves with periods greater than 5 minutes and acoustic waves with periods between 3 and 5 minutes have been detected at ionospheric heights (250-350 km) and associated with severe thunderstorms. Modeling results support these findings, indicating that acoustic waves should be able to reach 250-350 km within ~250 km horizontally of the source, and gravity waves should be able to propagate significantly further. However, the mechanism by which the acoustic waves are generated and the ubiquity of occurrence of both types of wave is unknown. We use GPS total electron content measurements to detect gravity and acoustic waves in the ionosphere. We perform a statistical study from 2005 May - July to compare the occurrence rate and horizontal extent of the waves to storm size and convective height from NEXRAD radar measurements. It is found that both gravity waves and acoustic wave horizontal extent is primarily associated with storm size and not convective height.
A device for locating acoustic wave emitting sources
International Nuclear Information System (INIS)
The invention relates to a device for locating acoustic wave emitting sources. A two dimensional sensor network, with diamond-shaped (or the like) meshes, is placed on the surface of a structure in which acoustic wave emitting sources are to be located. The sensors are arranged according to two groups, each of which is connected to a clock and a counter. Every signal fed into a mesh of the network inhibits all the other sensors not belonging to said mesh; the location of the source within the diamond-shaped mesh is achieved by triangulation. This can be applied to the detection of flaws in metal structures, e.g. in nuclear reactor vessels
High-Temperature Piezoelectric Crystals for Acoustic Wave Sensor Applications.
Zu, Hongfei; Wu, Huiyan; Wang, Qing-Ming
2016-03-01
In this review paper, nine different types of high-temperature piezoelectric crystals and their sensor applications are overviewed. The important materials' properties of these piezoelectric crystals including dielectric constant, elastic coefficients, piezoelectric coefficients, electromechanical coupling coefficients, and mechanical quality factor are discussed in detail. The determination methods of these physical properties are also presented. Moreover, the growth methods, structures, and properties of these piezoelectric crystals are summarized and compared. Of particular interest are langasite and oxyborate crystals, which exhibit no phase transitions prior to their melting points ∼ 1500 °C and possess high electrical resistivity, piezoelectric coefficients, and mechanical quality factor at ultrahigh temperature ( ∼ 1000 °C). Finally, some research results on surface acoustic wave (SAW) and bulk acoustic wave (BAW) sensors developed using this high-temperature piezoelectric crystals are discussed.
HF Doppler observations of acoustic waves excited by the earthquake
Ichinose, T.; Takagi, K.; Tanaka, T.; Okuzawa, T.; Shibata, T.; Sato, Y.; Nagasawa, C.; Ogawa, T.
1985-01-01
Ionospheric disturbances caused by the earthquake of a relatively small and large epicentral distance have been detected by a network of HF-Doppler sounders in central Japan and Kyoto station, respectively. The HF-Doppler data of a small epicentral distance, together with the seismic data, have been used to formulate a mechanism whereby ionospheric disturbances are produced by the Urakawa-Oki earthquake in Japan. Comparison of the dynamic spectra of these data has revealed experimentally that the atmosphere acts as a low-pass filter for upward-propagating acoustic waves. By surveying the earthquakes for which the magnitude M is larger than 6.0, researchers found the ionospheric effect in 16 cases of 82 seismic events. As almost all these effects have occurred in the daytime, it is considered that it may result from the filtering effect of the upward-propagating acoustic waves.
Impact of Acoustic Standing Waves on Structural Responses
Kolaini, Ali R.
2014-01-01
For several decades large reverberant chambers and most recently direct field acoustic testing have been used in the aerospace industry to test larger structures with low surface densities such as solar arrays and reflectors to qualify them and to detect faults in the design and fabrication. It has been reported that in reverberant chamber and direct acoustic testing, standing acoustic modes may strongly couple with the fundamental structural modes of the test hardware (Reference 1). In this paper results from a recent reverberant chamber acoustic test of a composite reflector are discussed. These results provide further convincing evidence of the acoustic standing wave and structural modes coupling phenomenon. The purpose of this paper is to alert test organizations to this phenomenon so that they can account for the potential increase in structural responses and ensure that flight hardware undergoes safe testing. An understanding of the coupling phenomenon may also help minimize the over and/or under testing that could pose un-anticipated structural and flight qualification issues.
Reformed Solitary Kinetic Alfvén Waves due to Dissipations and Auroral Electron Acceleration
Institute of Scientific and Technical Information of China (English)
WU De-Jin; CHAO Jih-Kwin; LEE Luo-Chuan; FENG Xue-Shang
2001-01-01
The physical nature of the auroral electron acceleration has been an outstanding problem in space physics for decades.Some recent observations from the auroral orbit satellites,FREJA and FAST,showed that large amplitude solitary kinetic Alfvén waves (SKAWs) are a common electromagnetic active phenomenon in the auroral magnetosphere. In a Iow-ββ/2 (i.e.,β/2 < me/mi < 1) plasma,the drift velocity of electrons relative to ions within SKAWs is much larger than thermal velocities of both electrons and ions.This leads to instabilities and causes dissipations of SKAWs.In the present work,based on the analogy of classical particle motion in a potential well,it is shown that a shock-like structure can be formed from SKAWs if dissipation effects are included.The reformed SKAWs with a shock-like structure have a local density jump and a net field-aligned electric potential drop of order of mev2A/e over a characteristic width of several )e.As a consequence,the reformed SKAWs can efficiently accelerate electrons field-aligned to the order of the local Alfvén velocity.In particular,we argue that this electron acceleration mechanism by reformed SKAWs can play an important role in the auroral electron acceleration problem.The result shows that not only the location of acceleration regions predicted by this model is well consistent with the observed auroral electron acceleration region of I 2 RE above the auroral ionosphere,but also the accelerated electrons from this region can obtain an energy of several keV and carry a field-aligned current of several/A/m2 which are comparable to the observations of auroral electrons.
High-Temperature Surface-Acoustic-Wave Transducer
Zhao, Xiaoliang; Tittmann, Bernhard R.
2010-01-01
Aircraft-engine rotating equipment usually operates at high temperature and stress. Non-invasive inspection of microcracks in those components poses a challenge for the non-destructive evaluation community. A low-profile ultrasonic guided wave sensor can detect cracks in situ. The key feature of the sensor is that it should withstand high temperatures and excite strong surface wave energy to inspect surface/subsurface cracks. As far as the innovators know at the time of this reporting, there is no existing sensor that is mounted to the rotor disks for crack inspection; the most often used technology includes fluorescent penetrant inspection or eddy-current probes for disassembled part inspection. An efficient, high-temperature, low-profile surface acoustic wave transducer design has been identified and tested for nondestructive evaluation of structures or materials. The development is a Sol-Gel bismuth titanate-based surface-acoustic-wave (SAW) sensor that can generate efficient surface acoustic waves for crack inspection. The produced sensor is very thin (submillimeter), and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. One major uniqueness of the Sol-Gel bismuth titanate SAW sensor is that it is easy to implement to structures of various shapes. With a spray coating process, the sensor can be applied to surfaces of large curvatures. Second, the sensor is very thin (as a coating) and has very minimal effect on airflow or rotating equipment imbalance. Third, it can withstand temperatures up to 530 C, which is very useful for engine applications where high temperature is an issue.
Surface acoustic wave probe implant for predicting epileptic seizures
Gopalsami, Nachappa; Kulikov, Stanislav; Osorio, Ivan; Raptis, Apostolos C.
2012-04-24
A system and method for predicting and avoiding a seizure in a patient. The system and method includes use of an implanted surface acoustic wave probe and coupled RF antenna to monitor temperature of the patient's brain, critical changes in the temperature characteristic of a precursor to the seizure. The system can activate an implanted cooling unit which can avoid or minimize a seizure in the patient.
Surface acoustic wave applications of lithium niobate thin films
International Nuclear Information System (INIS)
A technique combining metalorganic decomposition and rf sputtering is used to grow lithium niobate (LiNbO3) thin films on diamond/silicon substrates, and surface acoustic wave (SAW) filters are fabricated by depositing interdigital transducers onto the multilayer LiNbO3/diamond/silicon structures. Microwave characterization is achieved by using a network analyzer. Evidence is found for SAW propagation in these structures. These experimental findings agree with theoretical predictions
Electron-acoustic plasma waves: oblique modulation and envelope solitons
Kourakis, I.; Shukla, P. K.
2004-01-01
Theoretical and numerical studies are presented of the amplitude modulation of electron-acoustic waves (EAWs) propagating in space plasmas whose constituents are inertial cold electrons, Boltzmann distributed hot electrons and stationary ions. Perturbations oblique to the carrier EAW propagation direction have been considered. The stability analysis, based on a nonlinear Schroedinger equation (NLSE), reveals that the EAW may become unstable; the stability criteria depend on the angle $\\theta$...
Extremely Low-Loss Acoustic Phonons in a Quartz Bulk Acoustic Wave Resonator
Goryachev, Maxim; Ivanov, Eugene N; Galliou, Serge; Bourquin, Roger; Tobar, Michael E
2012-01-01
Low-loss, high frequency acoustic resonators cooled to millikelvin temperatures are a topic of great interest for application to hybrid quantum systems. When cooled to 20 mK, we show that resonant acoustic phonon modes in a Bulk Acoustic Wave (BAW) quartz resonator demonstrate exceptionally low loss (with $Q$-factors of order billions) at frequencies of 15.6 and 65.4 MHz, with a maximum $f.Q$ product of 7.8$\\times10^{16}$ Hz. Given this result, we show that the $Q$-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained. Such resonators possess the low losses crucial for electromagnetic cooling to the phonon ground state, and the possibility of long coherence and interaction times of a few seconds, allowing multiple quantum gate operations.
Volumetric measurements of a spatially growing dust acoustic wave
Williams, Jeremiah D.
2012-11-01
In this study, tomographic particle image velocimetry (tomo-PIV) techniques are used to make volumetric measurements of the dust acoustic wave (DAW) in a weakly coupled dusty plasma system in an argon, dc glow discharge plasma. These tomo-PIV measurements provide the first instantaneous volumetric measurement of a naturally occurring propagating DAW. These measurements reveal over the measured volume that the measured wave mode propagates in all three spatial dimensional and exhibits the same spatial growth rate and wavelength in each spatial direction.
Volumetric measurements of a spatially growing dust acoustic wave
Energy Technology Data Exchange (ETDEWEB)
Williams, Jeremiah D. [Physics Department, Wittenberg University, Springfield, Ohio 45504 (United States)
2012-11-15
In this study, tomographic particle image velocimetry (tomo-PIV) techniques are used to make volumetric measurements of the dust acoustic wave (DAW) in a weakly coupled dusty plasma system in an argon, dc glow discharge plasma. These tomo-PIV measurements provide the first instantaneous volumetric measurement of a naturally occurring propagating DAW. These measurements reveal over the measured volume that the measured wave mode propagates in all three spatial dimensional and exhibits the same spatial growth rate and wavelength in each spatial direction.
Energy scavenging system by acoustic wave and integrated wireless communication
Kim, Albert
The purpose of the project was developing an energy-scavenging device for other bio implantable devices. Researchers and scientist have studied energy scavenging method because of the limitation of traditional power source, especially for bio-implantable devices. In this research, piezoelectric power generator that activates by acoustic wave, or music was developed. Follow by power generator, a wireless communication also integrated with the device for monitoring the power generation. The Lead Zirconate Titanate (PZT) bimorph cantilever with a proof mass at the free end tip was studied to convert acoustic wave to power. The music or acoustic wave played through a speaker to vibrate piezoelectric power generator. The LC circuit integrated with the piezoelectric material for purpose of wireless monitoring power generation. However, wireless monitoring can be used as wireless power transmission, which means the signal received via wireless communication also can be used for power for other devices. Size of 74 by 7 by 7cm device could generate and transmit 100mVp from 70 mm distance away with electrical resonant frequency at 420.2 kHz..
VARIATION METHOD FOR ACOUSTIC WAVE IMAGING OF TWO DIMENSIONAL TARGETS
Institute of Scientific and Technical Information of China (English)
冯文杰; 邹振祝
2003-01-01
A new way of acoustic wave imaging was investigated. By using the Green function theory a system of integral equations, which linked wave number perturbation function with wave field, was firstly deduced. By taking variation on these integral equations an inversion equation, which reflected the relation between the little variation of wave number perturbation function and that of scattering field, was further obtained. Finally, the perturbation functions of some identical targets were reconstructed, and some properties of the novel method including converging speed, inversion accuracy and the abilities to resist random noise and identify complex targets were discussed. Results of numerical simulation show that the method based on the variation principle has great theoretical and applicable value to quantitative nondestructive evaluation.
Ion acoustic shock wave in collisional equal mass plasma
Energy Technology Data Exchange (ETDEWEB)
Adak, Ashish, E-mail: ashish-adak@yahoo.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Ghosh, Samiran, E-mail: sran-g@yahoo.com [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700 064 (India)
2015-10-15
The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.
Ion acoustic shock wave in collisional equal mass plasma
International Nuclear Information System (INIS)
The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments
Dual mode acoustic wave sensor for precise pressure reading
Mu, Xiaojing; Kropelnicki, Piotr; Wang, Yong; Randles, Andrew Benson; Chuan Chai, Kevin Tshun; Cai, Hong; Gu, Yuan Dong
2014-09-01
In this letter, a Microelectromechanical system acoustic wave sensor, which has a dual mode (lateral field exited Lamb wave mode and surface acoustic wave (SAW) mode) behavior, is presented for precious pressure change read out. Comb-like interdigital structured electrodes on top of piezoelectric material aluminium nitride (AlN) are used to generate the wave modes. The sensor membrane consists of single crystalline silicon formed by backside-etching of the bulk material of a silicon on insulator wafer having variable device thickness layer (5 μm-50 μm). With this principle, a pressure sensor has been fabricated and mounted on a pressure test package with pressure applied to the backside of the membrane within a range of 0 psi to 300 psi. The temperature coefficient of frequency was experimentally measured in the temperature range of -50 °C to 300 °C. This idea demonstrates a piezoelectric based sensor having two modes SAW/Lamb wave for direct physical parameter—pressure readout and temperature cancellation which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications using the dual mode behavior of the sensor and differential readout at the same time.
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
By making use of the generalized sine-Gordon equation expansion method, we find cnoidal periodic wave solutions and fundamental bright and dark optical solitarywave solutions for the fourth-order dispersive and the quintic nonlinear Schrodinger equation with self-steepening, and self-frequency shift. Moreover, we discuss the formation conditions of the bright and dark solitary waves.
Acoustic Wave Stimulated Enhanced Oil Recovery
Reichmann, Sven; Giese, Rüdiger; Amro, Mohammed
2013-04-01
High demand and the finite oil deposits will be a problem in the future. To temper the impact of a shortage in crude oil, a lot of research in the field of enhanced oil recovery (EOR) is worldwide ongoing. Using seismic waves to stimulate recovery of oil is known as seismic-EOR. The development of a stimulation procedure using seismic sources and the evaluation of the obtained data in a real oil field is the aim of the project WAVE.O.R. The project is funded by the German scientific society for oil, gas and coal (DGMK). The Technical University of Freiberg (TUBAF) and the German Research Center for Geosciences (GFZ) in Potsdam developed a flooding cell connected with magnetostrictive actuators as sources for seismic energy. This device is eligible to survey the impact of different seismic stimulation parameter like frequency, alignment, amplitude and rock characteristics on oil recovery. The obtained laboratory data of flooding experiments using seismic waves were analyzed for key features like water breakthrough point, oil recovery and oil fraction. New approach has been developed, which consists of the connection of a principal component analysis with a clustering algorithm. This new technique allows us a better understanding and thus prediction of the recovery behavior of oil bearing sediments. The experiments show promising possibilities to enhance oil recovery with seismic stimulation. Especially the combination of different frequencies between 100 Hz and 4000 Hz had a positive impact on oil recovery. The responsible mechanisms were identified and discussed. Data obtained with the laboratory device will be applied in a field test using a borehole device developed by the GFZ in the project "Seismic Prediction While Drilling" (SPWD). For this purpose experiments are conducted to obtain the radiation pattern of the seismic sources used by the SPWD device in a borehole. In addition, the development of a control setup for the 1-D actuator array is an aim of the
Guided wave opto-acoustic device
Energy Technology Data Exchange (ETDEWEB)
Jarecki, Jr., Robert L.; Rakich, Peter Thomas; Camacho, Ryan; Shin, Heedeuk; Cox, Jonathan Albert; Qiu, Wenjun; Wang, Zheng
2016-02-23
The various technologies presented herein relate to various hybrid phononic-photonic waveguide structures that can exhibit nonlinear behavior associated with traveling-wave forward stimulated Brillouin scattering (forward-SBS). The various structures can simultaneously guide photons and phonons in a suspended membrane. By utilizing a suspended membrane, a substrate pathway can be eliminated for loss of phonons that suppresses SBS in conventional silicon-on-insulator (SOI) waveguides. Consequently, forward-SBS nonlinear susceptibilities are achievable at about 3000 times greater than achievable with a conventional waveguide system. Owing to the strong phonon-photon coupling achievable with the various embodiments, potential application for the various embodiments presented herein cover a range of radiofrequency (RF) and photonic signal processing applications. Further, the various embodiments presented herein are applicable to applications operating over a wide bandwidth, e.g. 100 MHz to 50 GHz or more.
Acoustic tests of Lorentz symmetry using Bulk Acoustic Wave quartz oscillators
Goryachev, M; Haslinger, Ph; Mizrachi, E; Anderegg, L; Müller, H; Hohensee, M; Tobar, M E
2016-01-01
A new method of probing Lorentz invariance in the neutron sector is described. The method is baed on stable quartz bulk acoustic wave oscillators compared on a rotating table. Due to Lorentz-invariance violation, the resonance frequencies of acoustic wave resonators depend on the direction in space via a corresponding dependence of masses of the constituent elements of solids. This dependence is measured via observation of oscillator phase noise built around such devices. The first such experiment now shows sensitivity to violation down to the limit $\\tilde{c}^n_Q=(-1.8\\pm2.2)\\times 10^{-14}$ GeV. Methods to improve the sensitivity are described together with some other applications of the technology in tests of fundamental physics.
All-Optical Detection of Acoustic Pressure Waves with applications in Photo-Acoustic Spectroscopy
Westergaard, Philip G
2016-01-01
An all-optical detection method for the detection of acoustic pressure waves is demonstrated. The detection system is based on a stripped (bare) single-mode fiber. The fiber vibrates as a standard cantilever and the optical output from the fiber is imaged to a displacement-sensitive optical detector. The absence of a conventional microphone makes the demonstrated system less susceptible to the effects that a hazardous environment might have on the sensor. The sensor is also useful for measurements in high temperature (above $200^{\\circ}$C) environments where conventional microphones will not operate. The proof-of-concept of the all-optical detection method is demonstrated by detecting sound waves generated by the photo-acoustic effect of NO$_2$ excited by a 455 nm LED, where a detection sensitivity of approximately 50 ppm was achieved.
Uphill diffusion, zero-flux planes and transient chemical solitary waves in garnet
Vielzeuf, D.; Saúl, A.
2011-05-01
Diffusion profiles in minerals are increasingly used to determine the duration of geological events. For this purpose, the distinction between growth and diffusion zoning is critical; it requires the understanding of complex features associated with multicomponent diffusion. Seed-overgrowth interdiffusion experiments carried out in the range 1,050-1,250°C at 1.3 GPa have been designed to quantify and better understand Fe-Mg-Ca interdiffusion in garnet. Some of the diffusion profiles measured by analytical transmission electron microscope show characteristic features of multicomponent diffusion such as uphill diffusion, chemical solitary waves, zero-flux planes and complex diffusion paths. We implemented three different methods to calculate the interdiffusion coefficients of the D matrix from the experimental penetration curves and determined that with Ca as the dependent component, the crossed coefficients of the D matrix are negative. Experiments and numerical simulations indicate that: (1) uphill diffusion in garnet can be observed indifferently on the three components Fe, Mg and Ca, (2) it takes the form of complementary depletion/repletion waves and (3) chemical waves occur preferentially on initially flat concentration profiles. Derived D matrices are used to simulate the fate of chemical waves in time, in finite crystals. These examples show that the flow of atoms in multicomponent systems is not necessarily unidirectional for all components; it can change both in space along the diffusion profile and in time. Moving zero-flux planes in finite crystals are transitory features that allow flux reversals of atoms in the diffusion zone. Interdiffusion coefficients of the D matrices are also analyzed in terms of eigenvalues and eigenvectors. This analysis and the experimental results show that depending on the composition of the diffusion couple, (1) the shape of chemical waves and diffusion paths changes; (2) the width of the diffusion zone for each component
Ultrafast strain gauge: Observation of THz radiation coherently generated by acoustic waves
International Nuclear Information System (INIS)
The study of nanoscale, terahertz frequency (THz) acoustic waves has great potential for elucidating material and chemical interactions as well as nanostructure characterization. Here we report the first observation of terahertz radiation coherently generated by an acoustic wave. Such emission is directly related to the time-dependence of the stress as the acoustic wave crosses an interface between materials of differing piezoelectric response. This phenomenon enables a new class of strain wave metrology that is fundamentally distinct from optical approaches, providing passive remote sensing of the dynamics of acoustic waves with ultrafast time resolution. The new mechanism presented here enables nanostructure measurements not possible using existing optical or x-ray approaches
Ultrafast strain gauge: Observation of THz radiation coherently generated by acoustic waves
Energy Technology Data Exchange (ETDEWEB)
Armstrong, M; Reed, E; Kim, K; Glownia, J; Howard, W M; Piner, E; Roberts, J
2008-08-14
The study of nanoscale, terahertz frequency (THz) acoustic waves has great potential for elucidating material and chemical interactions as well as nanostructure characterization. Here we report the first observation of terahertz radiation coherently generated by an acoustic wave. Such emission is directly related to the time-dependence of the stress as the acoustic wave crosses an interface between materials of differing piezoelectric response. This phenomenon enables a new class of strain wave metrology that is fundamentally distinct from optical approaches, providing passive remote sensing of the dynamics of acoustic waves with ultrafast time resolution. The new mechanism presented here enables nanostructure measurements not possible using existing optical or x-ray approaches.
Structural changes of small amplitude kinetic Alfvén solitary waves due to second-order corrections
Energy Technology Data Exchange (ETDEWEB)
Choi, Cheong R. [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)
2015-10-15
The structural changes of kinetic Alfvén solitary waves (KASWs) due to higher-order terms are investigated. While the first-order differential equation for KASWs provides the dispersion relation for kinetic Alfvén waves, the second-order differential equation describes the structural changes of the solitary waves due to higher-order nonlinearity. The reductive perturbation method is used to obtain the second-order and third-order partial differential equations; then, Kodama and Taniuti's technique [J. Phys. Soc. Jpn. 45, 298 (1978)] is applied in order to remove the secularities in the third-order differential equations and derive a linear second-order inhomogeneous differential equation. The solution to this new second-order equation indicates that, as the amplitude increases, the hump-type Korteweg-de Vries solution is concentrated more around the center position of the soliton and that dip-type structures form near the two edges of the soliton. This result has a close relationship with the interpretation of the complex KASW structures observed in space with satellites.
Flow velocity measurement with the nonlinear acoustic wave scattering
Didenkulov, Igor; Pronchatov-Rubtsov, Nikolay
2015-10-01
A problem of noninvasive measurement of liquid flow velocity arises in many practical applications. To this end the most often approach is the use of the linear Doppler technique. The Doppler frequency shift of signal scattered from the inhomogeneities distributed in a liquid relatively to the emitted frequency is proportional to the sound frequency and velocities of inhomogeneities. In the case of very slow flow one needs to use very high frequency sound. This approach fails in media with strong sound attenuation because acoustic wave attenuation increases with frequency and there is limit in increasing sound intensity, i.e. the cavitation threshold. Another approach which is considered in this paper is based on the method using the difference frequency Doppler Effect for flows with bubbles. This method is based on simultaneous action of two high-frequency primary acoustic waves with closed frequencies on bubbles and registration of the scattered by bubbles acoustic field at the difference frequency. The use of this method is interesting since the scattered difference frequency wave has much lower attenuation in a liquid. The theoretical consideration of the method is given in the paper. The experimental examples confirming the theoretical equations, as well as the ability of the method to be applied in medical diagnostics and in technical applications on measurement of flow velocities in liquids with strong sound attenuation is described. It is shown that the Doppler spectrum form depends on bubble concentration velocity distribution in the primary acoustic beams crossing zone that allows one to measure the flow velocity distribution.
Flow velocity measurement with the nonlinear acoustic wave scattering
Energy Technology Data Exchange (ETDEWEB)
Didenkulov, Igor, E-mail: din@appl.sci-nnov.ru [Institute of Applied Physics, 46 Ulyanov str., Nizhny Novgorod, 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin ave., Nizhny Novgorod, 603950 (Russian Federation); Pronchatov-Rubtsov, Nikolay, E-mail: nikvas@rf.unn.ru [Lobachevsky State University of Nizhny Novgorod, 23 Gagarin ave., Nizhny Novgorod, 603950 (Russian Federation)
2015-10-28
A problem of noninvasive measurement of liquid flow velocity arises in many practical applications. To this end the most often approach is the use of the linear Doppler technique. The Doppler frequency shift of signal scattered from the inhomogeneities distributed in a liquid relatively to the emitted frequency is proportional to the sound frequency and velocities of inhomogeneities. In the case of very slow flow one needs to use very high frequency sound. This approach fails in media with strong sound attenuation because acoustic wave attenuation increases with frequency and there is limit in increasing sound intensity, i.e. the cavitation threshold. Another approach which is considered in this paper is based on the method using the difference frequency Doppler Effect for flows with bubbles. This method is based on simultaneous action of two high-frequency primary acoustic waves with closed frequencies on bubbles and registration of the scattered by bubbles acoustic field at the difference frequency. The use of this method is interesting since the scattered difference frequency wave has much lower attenuation in a liquid. The theoretical consideration of the method is given in the paper. The experimental examples confirming the theoretical equations, as well as the ability of the method to be applied in medical diagnostics and in technical applications on measurement of flow velocities in liquids with strong sound attenuation is described. It is shown that the Doppler spectrum form depends on bubble concentration velocity distribution in the primary acoustic beams crossing zone that allows one to measure the flow velocity distribution.
Overstability of acoustic waves in strongly magnetized anisotropic MHD shear flows
Uchava, E S; Tevzadze, A G; Poedts, S
2014-01-01
We present a linear stability analysis of the perturbation modes in anisotropic MHD flows with velocity shear and strong magnetic field. Collisionless or weakly collisional plasma is described within the 16-momentum MHD fluid closure model, that takes into account not only the effect of pressure anisotropy, but also the effect of anisotropic heat fluxes. In this model the low frequency acoustic wave is revealed into a standard acoustic mode and higher frequency fast thermo-acoustic and lower frequency slow thermo-acoustic waves. It is shown that thermo-acoustic waves become unstable and grow exponentially when the heat flux parameter exceeds some critical value. It seems that velocity shear makes thermo-acoustic waves overstable even at subcritical heat flux parameters. Thus, when the effect of heat fluxes is not profound acoustic waves will grow due to the velocity shear, while at supercritical heat fluxes the flow reveals compressible thermal instability. Anisotropic thermal instability should be also impor...
Determination of hydrocarbon levels in water via laser-induced acoustics wave
Bidin, Noriah; Hossenian, Raheleh; Duralim, Maisarah; Krishnan, Ganesan; Marsin, Faridah Mohd; Nughro, Waskito; Zainal, Jasman
2016-04-01
Hydrocarbon contamination in water is a major environmental concern in terms of foreseen collapse of the natural ecosystem. Hydrocarbon level in water was determined by generating acoustic wave via an innovative laser-induced breakdown in conjunction with high-speed photographic coupling with piezoelectric transducer to trace acoustic wave propagation. A Q-switched Nd:YAG (40 mJ) was focused in cuvette-filled hydrocarbon solution at various concentrations (0-2000 ppm) to induce optical breakdown, shock wave generation and later acoustic wave propagation. A nitro-dye (ND) laser (10 mJ) was used as a flash to illuminate and frozen the acoustic wave propagation. Lasers were synchronised using a digital delay generator. The image of acoustic waves was grabbed and recorded via charged couple device (CCD) video camera at the speed of 30 frames/second with the aid of Matrox software version 9. The optical delay (0.8-10.0 μs) between the acoustic wave formation and its frozen time is recorded through photodetectors. A piezo-electric transducer (PZT) was used to trace the acoustic wave (sound signal), which cascades to a digital oscilloscope. The acoustic speed is calculated from the ratio of acoustic wave radius (1-8 mm) and optical time delay. Acoustic wave speed is found to linearly increase with hydrocarbon concentrations. The acoustic signal generation at higher hydrocarbon levels in water is attributed to supplementary mass transfer and impact on the probe. Integrated high-speed photography with transducer detection system authenticated that the signals indeed emerged from the laser-induced acoustic wave instead of photothermal processes. It is established that the acoustic wave speed in water is used as a fingerprint to detect the hydrocarbon levels.
Synchronization of the dust acoustic wave under microgravity
Ruhunusiri, W. D. Suranga; Goree, J.
2013-10-01
Synchronization is a nonlinear phenomenon where a self-excited oscillation, like a wave in a plasma, interacts with an external driving, resulting in an adjustment of the oscillation frequency. To prepare for experiments under microgravity conditions using the PK-4 facility on the International Space Station, we perform a laboratory experiment to observe synchronization of the self-excited dust acoustic wave. An rf glow discharge argon plasma is formed by applying a low power radio frequency voltage to a lower electrode. A 3D dust cloud is formed by levitating 4.83 micron microspheres inside a glass box placed on the lower electrode. The dust acoustic wave is self-excited with a natural frequency of 22 Hz due to an ion streaming instability. A cross section of the dust cloud is illuminated by a vertical laser sheet and imaged from the side with a digital camera. To synchronize the wave, we sinusoidally modulate the overall ion density. Differently from previous experiments, we use a driving electrode that is separate from the electrode that sustains the plasma, and we characterize synchronization by varying both driving amplitude and frequency. Supported by NASA's Physical Science Research Program.