Skip to Main content Skip to Navigation
Journal articles

The stability of stratified spatially periodic shear flows at low Péclet number

Pascale Garaud 1, * Basile Gallet 2 Tobias Bischoff 3 
* Corresponding author
2 SPHYNX - Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes
SPEC - UMR3680 - Service de physique de l'état condensé, IRAMIS - Institut Rayonnement Matière de Saclay
Abstract : This work addresses the question of the stability of stratified, spatially periodic shear flows at low Péclet number but high Reynolds number. This little-studied limit is motivated by astrophysical systems, where the Prandtl number is often very small. Furthermore, it can be studied using a reduced set of “low-Péclet-number equations” proposed by Lignières [“The small-Péclet-number approximation in stellar radiative zones, (Astron. Astrophys. 348, 933–939 (1999). Through a linear stability analysis, we first determine the conditions for instability to infinitesimal perturbations. We formally extend Squire’s theorem to the low-Péclet-number equations, which shows that the first unstable mode is always two-dimensional. We then perform an energy stability analysis of the low-Péclet-number equations and prove that for a given value of the Reynolds number, above a critical strength of the stratification, any smooth periodic shear flow is stable to perturbations of arbitrary amplitude. In that parameter regime, the flow can only be laminar and turbulent mixing does not take place. Finding that the conditions for linear and energy stability are different, we thus identify a region in parameter space where finite-amplitude instabilities could exist. Using direct numerical simulations, we indeed find that the system is subject to such finite-amplitude instabilities. We determine numerically how far into the linearly stable region of parameter space turbulence can be sustained
Document type :
Journal articles
Complete list of metadata

Cited literature [33 references]  Display  Hide  Download
Contributor : Dominique GIRARD Connect in order to contact the contributor
Submitted on : Wednesday, March 29, 2017 - 3:11:41 PM
Last modification on : Thursday, March 10, 2022 - 3:58:07 PM
Long-term archiving on: : Friday, June 30, 2017 - 3:25:25 PM


Files produced by the author(s)



Pascale Garaud, Basile Gallet, Tobias Bischoff. The stability of stratified spatially periodic shear flows at low Péclet number. Physics of Fluids, American Institute of Physics, 2015, 27, pp.84104. ⟨10.1063/1.4928164⟩. ⟨cea-01497917⟩



Record views


Files downloads