English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

An analytical approach is carried out that provides an inviscid stabilitycriterion for the strato-rotational instability (in short SRI) occurring in aTaylor-Couette system. The control parameters of the problem are the rotationratio $\mu$ and the radius ratio $\eta$. The study is motivated by recentexperimental \cite{legal} and numerical \cite{rudi, rudi2} results reportingthe existence of unstable modes beyond the Rayleigh line for centrifugalinstability ($\mu =\eta^2$). The modified Rayleigh criterion for stablystratified flows provides the instability condition, $\mu<1$, while inexperiments unstable modes were never found beyond the line $\mu=\eta$. Takinginto account finite gap effects, we consider non axisymmetric perturbationswith azimuthal wavenumber $l$ in the limit $l Fr<<1$, where $Fr$ is the Froudenumber. We derive a necessary condition for instability : $\mu < \mu^*$ where$\mu^*$, a function of $\eta$, takes the asymptotic values, $\mu^* \to 1$ inthe narrow gap limit, and $\mu^* \to 2\eta^2(1+\eta)$ in the wide gap limit, inagreement with recent numerical findings. A stronger condition, $\mu<\eta$, isfound when $\eta>0.38$, in agreement with experimental results obtained for$\eta=0.8$. Whatever the gap size, instability is predicted for values of $\mu$larger than the critical one, $\mu_c=\eta^2$, corresponding to centrifugalinstability.

Instability criterion for oblique modes in stratified circular Couette flow