Longitudinal wave

About: Longitudinal wave is a research topic. Over the lifetime, 16891 publications have been published within this topic receiving 349170 citations.

Elastic Waves in Layered Media

Abstract: (1958). Elastic Waves in Layered Media. Geologiska Foreningen i Stockholm Forhandlingar: Vol. 80, No. 1, pp. 128-129.

Waves in plasmas

Abstract: Wave normal surfaces waves in a cold uniform plasma causality, acoustic waves and simple drift waves energy flow and accessibility Kruskal-Schwarzschild solutions for a bounded plasma oscillations in bonded plasmas plasma models with discrete structure longitudinal oscillations in a plasma of continuous structure absolute and convective instability susceptibilities for a hot plasma in a magnetic field waves in magnetized uniform media effects on waves from weak collisions reflection, absorption and mode conversion nonuniform plasmas the straight-trajectory approximation quasilinear diffusion quasilinear diffusion in a magnetized plasma bounce-averaged quasilinear diffusion in a magnetized plasma bounce-averaged quasilinear diffusion.

The propagation of electromagnetic waves in plasmas.

Abstract: Green's function techniques are used to treat the propagation of electromagnetic waves in uniform, weakly interacting plasmas near equilibrium in the absence of external magnetic fields. The frequency and the damping of electromagnetic waves in a medium are related to the local complex conductivity tensor, which is calculated by the diagrammatic techniques of modern field theory. Physical quantities are calculated in terms of a consistent many-particle perturbation expansion in powers of a (weak) coupling parameter. An open-diagram technique is introduced which simplifies the calculation of absorptive parts. For longwavelength longitudinal waves (i.e., electron plasma oscillations) it is found that the main absorption mechanism in the electron-ion plasma is the two-particle collision process appropriately corrected for collective effects and not the one-particle (or Landau) damping process. Electron-ion collisions produce a damping effect which remains finite for long wavelengths. The effect of electron-electron collisions vanishes in this limit. The absorption of transverse radiation is also considered; calculations for the electron-ion plasma are in essential agreement with the recent work of Dawson and Oberman. The results for the absorptive part of the conductivity tensor for long-wavelength electromagnetic waves in a plasma where the phase velocity au/k is much greater than the rms particle velocity is for the electron-ion plasma: O„O,~kgb C, ( )

On the generation of surface waves by shear flows

Abstract: A mechanism for the generation of surface waves by a parallel shear flow U(y) is developed on the basis of the inviscid Orr-Sommerfeld equation. It is found that the rate at which energy is transferred to a wave of speed c is proportional to the profile curvature -U"(y) at that elevation where U = c. The result is applied to the generation of deep-water gravity waves by wind. An approximate solution to the boundary value problem is developed for a logarithmic profile and the corresponding spectral distribution of the energy transfer coefficient calculated as a function of wave speed. The minimum wind speed for the initiation of gravity waves against laminar dissipation in water having negligible mean motion is found to be roughly 100cm/sec. A spectral mean value of the sheltering coefficient, as defined by Munk, is found to be in order-of-magnitude agreement with total wave drag measurements of Van Dorn. It is concluded that the model yields results in qualitative agreement with observation, but truly quantitative comparisons would require a more accurate solution of the boundary value problem and more precise data on wind profiles than are presently available. The results also may have application to the flutter of membranes and panels.