Heat exchange and deceleration of a magnetized body in a rarefied plasma flow

It is shown that the rotation of the intrinsic magnetic field relative to the velocity vector of an incoming plasma flow is an effective means of controlling convective heat transfer and aerodynamic efficiency of a magnetized axisymmetric dielectric body.     

On the impact of anisotropy on dispersion spectra of acoustic waves in platesImpact de l'anisotropie sur les spectres de dispersion des ondes élastiques dans des plaques

A brief overview is given of specific features that can (or cannot) appear in the dispersion spectra of traction-free elastic homogeneous plates due to anisotropy. Its effect on the overall spectral configuration and on the short and long wave trends is illuminated with a link to anisotropic traits of bulk and surface waves. Relevant classical and recent results are put together, and new points are established. To cite this article: A.L. Shuvalov, C. R. Mecanique 334 (2006).     

On the backward Lamb waves near thickness resonances in anisotropic plates

A closed-form expression for the leading-order dispersion coefficient, describing the trend of Lamb-wave branches at their onset from thickness resonances, is derived for an arbitrary anisotropic plate. The sign of this coefficient and hence of the in-plane group velocity near cutoffs decides the existence or non-existence of the backward Lamb waves without a necessity to calculate the dispersion branches. A link between the near-cutoff dispersion of Lamb waves and the curvature of bulk-wave slowness curves in a sagittal plane is analyzed. It is established that a locally concave slowness curve of a bulk mode entails the backward Lamb waves at the onset of branches emerging from this bulk mode resonances of high enough order. A simple sufficient condition for no backward Lamb waves near the resonances associated with a convex slowness curve is also noted. Two special cases are discussed: the first involves the coupled resonances of degenerate bulk waves, and the second concerns quasi-degenerate resonances which give rise to pairs of dispersion branches with a quasilinear positive and negative onset. Occasions of the backward Lamb waves in isotropic plate materials are tabulated.