The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform

Elena Tobisch - One of the best experts on this subject based on the ideXlab platform.

  • Energy spectrum of the ensemble of weakly nonlinear gravity-capillary waves on a Fluid Surface
    Journal of Experimental and Theoretical Physics, 2014
    Co-Authors: Elena Tobisch
    Abstract:

    We consider nonlinear gravity-capillary waves with the nonlinearity parameter ɛ ∼ 0.1–0.25. For this nonlinearity, time scale separation does not occur and the kinetic wave equation does not hold. An energy cascade in this case is built at the dynamic time scale (D-cascade) and is computed by the increment chain equation method first introduced in [15]. We for the first time compute an analytic expression for the energy spectrum of nonlinear gravity-capillary waves as an explicit function of the ratio of Surface tension to the gravity acceleration. We show that its two limits—pure capillary and pure gravity waves on a Fluid Surface—coincide with the previously obtained results. We also discuss relations of the D-cascade model with a few known models used in the theory of nonlinear waves such as Zakharov’s equation, resonance of modes with nonlinear Stokes-corrected frequencies, and the Benjamin-Feir index. These connections are crucial in understanding and forecasting specifics of the energy transport in a variety of multicomponent wave dynamics, from oceanography to optics, from plasma physics to acoustics.

  • Energy spectrum of ensemble of weakly nonlinear gravity-capillary waves on a Fluid Surface
    arXiv: Fluid Dynamics, 2014
    Co-Authors: Elena Tobisch
    Abstract:

    In this Letter we regard nonlinear gravity-capillary waves with parameter of nonlinearity being $\varepsilon \sim 0.1 \div 0.25$. For this nonlinearity time scale separation does not occur and kinetic wave equation does not hold. An energy cascade in this case is built at the dynamic time scale (D-cascade) and is computed by the increment chain equation method first introduced in \emph{Kartashova, \emph{EPL} \textbf{97} (2012), 30004.} We compute for the first time an analytical expression for the energy spectrum of nonlinear gravity-capillary waves as an explicit function depending on the ratio of Surface tension to the gravity acceleration. It is shown that its two limits - pure capillary and pure gravity waves on a Fluid Surface - coincide with the previously obtained results. We also discuss relations of the model of D-cascade with a few known models used in the theory of nonlinear waves such as Zakharov's equation, resonance of the modes with nonlinear Stokes corrected frequencies and Benjamin-Feir index. These connections are crucial in the understanding and forecasting specifics of the energy transport in a variety of multi-component wave dynamics, from oceanography to optics, from plasma physics to acoustics.

Hany Ghoneim - One of the best experts on this subject based on the ideXlab platform.

  • Experimental investigation of the Fluid Surface damping technique
    Smart Structures and Materials 1998: Passive Damping and Isolation, 1998
    Co-Authors: Shpend Demiri, Hany Ghoneim
    Abstract:

    A Fluid Surface damping (FSD) element has been designed, produced and applied for the vibration suppression of a cantilever aluminum beam. The experimental steady-state frequency response of the treated beam, measured at the free end and subjected to a burst white noise excitation at the base, is determined and compared with the corresponding analytical results. The comparison shows a disagreement between the predicted and experimental results. Discussion of the potential sources of disagreement and of possible remedial measures is presented.

  • Fluid Surface Damping: A Technique for Vibration Suppression of Beams
    Shock and Vibration, 1997
    Co-Authors: Hany Ghoneim
    Abstract:

    A Fluid Surface damping (FSD) technique for vibration suppression of beamlikestructures is proposed. The technique is a modification of the Surface layer damping method. Two viscoelastic Surface layers containing Fluid-filled cavities are attached symmetrically to the opposite Surfaces of the beam. The cavities on one side are attached to the corresponding cavities on the other side via connection passages. As the beam vibrates, the Fluid is pumped back and forth through the connecting passages. Therefore, in addition to the viscoelastic damping provided by the Surface layers, the technique offers viscous damping due to the Fluid flow through the passage. A mathematical model for the proposed technique is developed, normalized, and solved in the frequency domain to investigate the effect of various parameters on the vibration suppression of a cantilever beam. The steady-state frequency response for a base white-noise excitation is calculated at the beam's free tip and over a frequency range containing the first five resonant frequencies. The parameters investigated are the flow-through passage viscous resistance, the length and location of the layers, the hydraulic capacitance of the Fluid-filled cavities, and inertia of the moving Fluid (hydraulic inertance). Results indicate that the proposed technique has promising potential in the field of vibration suppression of beamlike structures. With two FSD elements, all peak vibration amplitudes can be well suppressed over the entire frequency spectrum studied.

  • Fluid Surface damping versus constrained layer damping for vibration suppression of simply supported beams
    Smart Structures and Materials 1997: Passive Damping and Isolation, 1997
    Co-Authors: Hany Ghoneim
    Abstract:

    A Fluid Surface damping (FSD) technique proposed for vibration suppression of beam-like structures is applied to a generic simply supported aluminum beam. The steady-state frequency response of the FSD-treated beam at the vicinity of one end, due to an applied white noise displacement excitation at the other end, is determined using the finite element method. The response is found over a range of frequency covering the first four resonant frequencies and over a wide temperature range. Comparison of the results with the corresponding ones of a beam treated with the constrained layer damping method indicates that the FSD technique has a much greater potential for the vibration suppression of beam-like structures. Results also indicate that the FSD technique can provide a good vibration suppression over a wider temperature range.

Sidney R Nagel - One of the best experts on this subject based on the ideXlab platform.

  • scaling at the selective withdrawal transition through a tube suspended above the Fluid Surface
    Physical Review Letters, 2002
    Co-Authors: Itai Cohen, Sidney R Nagel
    Abstract:

    In the selective withdrawal experiment Fluid is withdrawn through a tube with its tip suspended a distance S above an unperturbed two-Fluid interface. At low withdrawal rates, Q, the interface forms a steady state hump and only the upper Fluid is withdrawn. When Q is increased (or S decreased), the interface undergoes a transition so that the lower Fluid is entrained with the upper one, forming a thin steady-state spout. Near this discontinuous transition the hump curvature becomes very large and displays power-law scaling behavior. This scaling is used to show that steady-state profiles for humps at different flow rates and tube heights can all be scaled onto a single similarity profile.

Eiki Goto - One of the best experts on this subject based on the ideXlab platform.

  • Quantification of tear interference image: tear Fluid Surface nanotechnology.
    Cornea, 2004
    Co-Authors: Eiki Goto
    Abstract:

    PURPOSE: To review the literature on lipid supplementation therapy for dry eye and on image analysis using tear interference images from the specific tear lipid layer interference camera DR-1. METHODS: Systematic literature review of lipid supplementation therapy for lipid tear deficiency dry eye, kinetic analysis of tear interference images using DR-1 camera, and computer-synthesized interference color chart for DR-1 camera. CONCLUSION: To establish lipid supplementation therapy, a quantification system of tear lipid layer is required. Tear lipid thickness could be quantified using a computer-synthesized interference color chart system.

Song Ji - One of the best experts on this subject based on the ideXlab platform.