Spatial aspect of wave transformations in astrophysical flows

The phenomenon of Shear Induced wave Transformations (SITs) (Chagelishvili et al. 1996), is a common feature of flows, sustaining n > 1 mode of wave m otion. Until now this "nonmodal" phenomenon was described only in terms of the time evolution of individual Fourier harmonics of perturbations in the space of wave numbers (k-space). In this paper we present the results of th e first, direct numerical simulations of SITs, giving compelling evidence i n favor of the robust and recognizable character of SITs. The importance of these results for an understanding of physical processes in astrophysical shear flows is pointed out. Namely, concrete astrophysical situations (sola r plasma flows, galactic gaseous disks, accretion disks and accretion-eject ion flows), where this approach may help to shed some light on observationa l appearances of related objects, are indicated and discussed.