Experimental analysis of the Strato-rotational Instability in a cylindrical Couette flow

TL;DR

This paper experimentally investigates the Strato-rotational Instability in cylindrical Couette flow, confirming non-axisymmetric, oscillatory unstable modes below the Rayleigh line, with implications for accretion disk dynamics.

Contribution

First detailed experimental analysis of SRI destabilization below the Rayleigh line in stratified cylindrical Couette flow.

Findings

Unstable modes are non-axisymmetric and oscillatory.

SRI occurs as azimuthal velocity decreases radially.

Results align with recent theoretical and numerical predictions.

Abstract

This study is devoted to the experimental analysis of the Strato-rotational Instability (SRI). This instability affects the classical cylindrical Couette flow when the fluid is stably stratified in the axial direction. In agreement with recent theoretical and numerical analyses, we describe for the first time in detail the destabilization of the stratified flow below the Rayleigh line (i.e. the stability threshold without stratification). We confirm that the unstable modes of the SRI are non axisymmetric, oscillatory, and take place as soon as the azimuthal linear velocity decreases along the radial direction. This new instability is relevant for accretion disks.