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Shihchuan Gou - One of the best experts on this subject based on the ideXlab platform.
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transition to quantum turbulence in a bose einstein condensate through the Bending Wave instability of a single vortex ring
Physical Review A, 2008Co-Authors: Tzyyleng Horng, C H Hsueh, Shihchuan GouAbstract:We investigate the dynamics of an unstable vortex ring in a pancake-shaped Bose-Einsten condensate by solving the Gross-Pitaevskii equation numerically. It is found that a quasisteady turbulent state with long relaxation time can be achieved through the disruption of a perturbed vortex ring in the condensate owing to the Bending-Wave instability. We verify that this quantum turbulent state is characterized by Kolmogorov energy spcetrum.
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Bending Wave instability of a vortex ring in a trapped bose einstein condensate
Physical Review A, 2006Co-Authors: Tzyyleng Horng, Shihchuan Gou, Taichia LinAbstract:use a scheme developed by Svidzinsky and Fetter, which utilizes the quantum analog of Biot-Savart law to determine the local velocity for each element of the vortex 16. The velocity formula is derived from the time dependent Gross-Pitaevskii equation by the method of matched asymptotic expansions in the Thomas-Fermi TF limit. To be specific, we shall consider a trapping potential Vx=m 2 r 2 +z z 2 /2 in the cylindrical coordinates r,,z, with the aspect ratio defined by =z/. The density profile of the condensate is given by x =01r 2 /R 2 z 2 /R z in the TF limit, where R =2/m 2 1/2 and Rz=2/m z 1/2 are, respectively, the radial and axial TF radii of the trapped BEC; is the chemical potential and 0=m/4 2 a is the central particle density. Thus, the velocity of a vortex line element at x in a nonrotating trap is given by 16
Tzyyleng Horng - One of the best experts on this subject based on the ideXlab platform.
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transition to quantum turbulence in a bose einstein condensate through the Bending Wave instability of a single vortex ring
Physical Review A, 2008Co-Authors: Tzyyleng Horng, C H Hsueh, Shihchuan GouAbstract:We investigate the dynamics of an unstable vortex ring in a pancake-shaped Bose-Einsten condensate by solving the Gross-Pitaevskii equation numerically. It is found that a quasisteady turbulent state with long relaxation time can be achieved through the disruption of a perturbed vortex ring in the condensate owing to the Bending-Wave instability. We verify that this quantum turbulent state is characterized by Kolmogorov energy spcetrum.
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Bending Wave instability of a vortex ring in a trapped bose einstein condensate
Physical Review A, 2006Co-Authors: Tzyyleng Horng, Shihchuan Gou, Taichia LinAbstract:use a scheme developed by Svidzinsky and Fetter, which utilizes the quantum analog of Biot-Savart law to determine the local velocity for each element of the vortex 16. The velocity formula is derived from the time dependent Gross-Pitaevskii equation by the method of matched asymptotic expansions in the Thomas-Fermi TF limit. To be specific, we shall consider a trapping potential Vx=m 2 r 2 +z z 2 /2 in the cylindrical coordinates r,,z, with the aspect ratio defined by =z/. The density profile of the condensate is given by x =01r 2 /R 2 z 2 /R z in the TF limit, where R =2/m 2 1/2 and Rz=2/m z 1/2 are, respectively, the radial and axial TF radii of the trapped BEC; is the chemical potential and 0=m/4 2 a is the central particle density. Thus, the velocity of a vortex line element at x in a nonrotating trap is given by 16
Andrew N. Norris - One of the best experts on this subject based on the ideXlab platform.
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Flexural edge Waves and comments on 'a new Bending Wave solution for the classical plate equation' [J. Acoust. Soc. Am. 104, 2220-2222 (1998)]
The Journal of the Acoustical Society of America, 2000Co-Authors: Andrew N. Norris, Victor V. Krylov, I.d. AbrahamsAbstract:A brief review is presented of the theory of flexural edge Waves, first predicted in 1960 by Yu K. Konenkov using Kirchhoff plate theory. It is demonstrated that the flexural edge Wave is also predicted by Mindlin’s plate theory, and that the prediction agrees with measured data. It is noted that the edge Wave was erroneously presented as a new type of Bending Wave solution in a recently published paper in this journal.
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Bending-Wave diffraction from strips and cracks on thin plates
The Quarterly Journal of Mechanics and Applied Mathematics, 1994Co-Authors: Andrew N. Norris, Zhang WangAbstract:Two canonical problems concerning scattering of Bending Waves in thin plates are solved. The scatterers are either a semi infinite rigid strip or a semi infinite crack in an otherwise uniform plate of infinite extent. The ewact scattered Waves are respresented by Fourier integrals obained using the Wiener Hopf method. The far field diffraction coefficient for the rigid strip isindependent of the material parameters, and is thus a universal parameter
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Experimental observation of Bending Wave localization
The Journal of the Acoustical Society of America, 1993Co-Authors: George D. Cody, Minyao Zhou, Ping Sheng, Andrew N. NorrisAbstract:Localization of Bending Waves has been observed for the first time for two-dimensional (2-D) acoustic Wave propagation in an inhomogeneous (rough) composite system consisting of a steel plate decorated with Lucite blocks. A significant experimental feature of the localized modes is an exponential decay of the mode intensity from their peaked centers, with a decay length that increases as (fo — f)-1 when the mode frequency f approaches a quasi-mobility edge fo. The minimum attenuation length is of the order of a block diagonal and is about 40% of the Bending Wave’s Wavelength. The experimental data, as well as results of finite-element calculations, suggest that the source of the localization phenomenon is strong scattering of the Bending Wave by shear resonances of the Lucite blocks. This result supports the theoretical prediction that resonant scattering enhances localization. It suggests that the Bending-Wave regime of a composite plate is particularly convenient for the study of classical localization in 2-D and at higher frequencies in 3-D. Finally, the generic nature of the localization phenomenon suggests its potential use as a tunable attenuation mechanism for Bending Waves.
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Observation of Bending Wave localization and quasi mobility edge in two dimensions.
Physical review letters, 1992Co-Authors: George D. Cody, Minyao Zhou, Ping Sheng, Andrew N. NorrisAbstract:Localization of Bending Waves is observed on a steel plate decorated with Lucite blocks. A significant experimental feature of the localized modes is an exponential decay of the mode intensity from their peaked centers, with a decay length that increases as (f 0 -f 1 ) -1 when the mode frequency f approaches a quasi mobility edge f 0 . Our experimental results, together with finite-element calculations, support the mechanism of strong Bending Wave scattering by the Lucite block resonances as the source of the localization phenomenon
Annie Ross - One of the best experts on this subject based on the ideXlab platform.
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Influence of partial constrained layer damping on the Bending Wave propagation in an impacted viscoelastic sandwich
International Journal of Solids and Structures, 2013Co-Authors: Boubaker Khalfi, Annie RossAbstract:AbstractThis paper presents a parametric model to study the transient Bending Wave propagation in a viscoelastic sandwich plate due to impact loading. The effect of partial constrained layer damping (PCLD) geometry on Wave propagation is investigated by comparing with propagation in single layer elastic plate. Several boundary conditions are also considered, and their effect on Wave propagation is highlighted.The equation of motion is obtained from Lagrange’s equations. For the single layer plate, the governing equation is solved in time domain using Newman and Wilson method. For the plate with PCLD, the frequency dependant viscoelastic behavior of the core is represented by Prony series; the equation of motion is converted into frequency domain using Fourier transform the displacement is obtained in the frequency domain and is converted into time domain with the Inverse Fast Fourier Transform.The model was validated in our previous paper (Khalfi and Ross (2013)) with experimental results, additional validation is carried in this paper with literature, and good agreement is recorded. The results show that the plate covered with PCLD remains a dispersive medium. The shape of the Wave is mainly related to the sandwich stiffness while the viscoelastic layer contributes in reducing the amplitude and speed of propagation. The particularity of this transient model lies in its ability to follow the shape of the Bending Wave at all times to observe formation, propagation and disappearance. With this model, the influence of any structural input parameters on the Bending Wave can be studied. The findings presented will also serve as a research base for more advanced horizons
Joseph M. Hahn - One of the best experts on this subject based on the ideXlab platform.
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The Secular Evolution of a Close Ring‐Satellite System: The Excitation of Spiral Bending Waves at a Nearby Gap Edge
The Astrophysical Journal, 2007Co-Authors: Joseph M. HahnAbstract:The secular perturbations exerted by an inclined satellite orbiting in a gap in a broad planetary ring tends to excite the inclinations of the nearby ring particles, and the ring's self-gravity can allow that disturbance to propagate away in the form of a spiral Bending Wave. The amplitude of this spiral Bending Wave is determined, as well as the Wavelength, which shrinks as the Waves propagate outwards due to the effects of the central planet's oblateness. The excitation of these Bending Waves also damps the satellite's inclination I. This secular I damping is also compared to the inclination excitation that is due to the satellite's many other vertical resonances in the ring, and the condition for inclination damping is determined. The secular I damping is likely responsible for confining the orbits of Saturn's two known gap-embedded moons, Pan and Daphnis, to the ring plane.Comment: 31 pages, 8 figure
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Damping of Orbital Inclinations by Bending Waves
Icarus, 1994Co-Authors: William R. Ward, Joseph M. HahnAbstract:Abstract An inclined secondary orbiting in a disk will launch Bending Waves from resonance sites where the Doppler shifted forcing frequency matches the disk's natural frequency for vertical oscillations. These vertical resonances are of two types: external resonances falling interior and exterior to the perturber's semimajor axis that excite its inclination and coorbiting resonances that fall at the perturber's orbit and damp its inclination. We show that torques from coorbiting resonances dominate the Bending Wave interaction for a constant density disk. In this case the inclination ultimately decays and an estimate of the characteristic time scale for this process is made.