Stability of elliptic flow with a horizontal axis under stable stratification

Effects of stratification on the three dimensional instability of elliptic flow having a horizontal axis are investigated. It is revealed that the stratification works fundamentally to suppress the instability. However, its responses to increasing stratification are different depending on situations of the elliptic flow in a vertical plane. Generally, the instability tends to be dumped further when the longer axis of the elliptic flow is oriented vertical rather than horizontal.