Speaker
Roberta Bianchini
(Consiglio Nazionale delle Ricerche)
Description
Abstract: Stably stratified fluids (e.g., oceans and atmosphere) support internal waves that are fundamental to oceanic circulation and atmospheric dynamics. We present the first rigorous proof of instability for small-amplitude internal waves, establishing the existence of an unstable spectrum for the Boussinesq equations linearised about a traveling wave. The analysis combines a Floquet–Bloch decomposition with a variant of Kato’s similarity transformation, exploiting the wave’s structure. In a specific regime, the resulting growth rates agree with previous theoretical predictions for Triadic Resonant Instability of internal waves.