Methods of Plasma Theory B.Flow and its Non-Hermiticity

Abstract

A complete spectral analysis of a non-Hermitian generator has been shown for a surface-wave model describing the Kelvin-Helmholtz instability. The canonical form of the generator contains a Jordan block in the con- tinuous spectrum, which represents resonant interaction of a surface wave and ambient shear flow due to the overlapping of their frequencies. Secular amplification (or a long-term modulation) of oscillations is induced by the resonant (or near resonant) interactions.