Аннотация:Internal wave attractors are formed as result of focusing of internal gravity waves in a confined domain of stably
stratified fluid due to peculiarities of reflections properties [1]. The energy injected into domain due to external
perturbation, is concentrated along the path formed by the attractor. The existence of attractors was predicted
theoretically and proved both experimentally and numerically [1-4]. Dynamics of attractors is greatly influenced
by geometrical focusing, viscous dissipation and nonlinearity. The experimental setup features Schmidt number
equal to 700 which impose constraints on resolution in numerical schemes. Also for investigation of stability on
large time intervals (about 1000 periods of external forcing) numerical viscosity may have significant impact.
For these reasons, we have chosen spectral element method for investigation of this problem, what allows
to carefully follow the nonlinear dynamics. We present cross-comparison of experimental observations and
numerical simulations of long-term behavior of wave attractors. Fourier analysis and subsequent application of
Hilbert transform are used for filtering of spatial components of internal-wave field [5]. The observed dynamics
shows a complicated coupling between the effects of local instability and global confinement of the fluid domain.
The unstable attractor is shown to act as highly efficient mixing box providing the efficient energy pathway from
global-scale excitation to small-scale wave motions and mixing.