000014575 001__ 14575
000014575 005__ 20161115100155.0
000014575 04107 $$aeng
000014575 046__ $$k2016-08-21
000014575 100__ $$aChomaz, Jean-Marc
000014575 24500 $$aOptimal Perturbations of a Counter-rotating Vortex Pair in Stratified Flows

000014575 24630 $$n24.$$p24th International Congress of Theoretical and Applied Mechanics - Book of Papers
000014575 260__ $$bInternational Union of Theoretical and Applied Mechanics, 2016
000014575 506__ $$arestricted
000014575 520__ $$2eng$$aThis paper investigates the three dimensional perturbations developping on a pair of horizontal counter-rotating vortices in stably stratified flow. The 2D flow is unsteady and the stability is reformulated by searching transient energy growth of perturbations around a time varying flow. For weak and moderate stratifications (large Froude numbers), the stratification acts on a long timescale compared to the advection time of the dipole, when 3D instabilities are added, transient analysis at different instant retrieves the instability peaks corresponding to the Crow instability for the long wavelengths and to the elliptic instability. This shows the validity of the quasi-steady approximation and that stratification destabilizes the flow by bringing vortices closer. For strong stratifications (Froude numbers smaller than 2), the quasi-steady approximation is not valid. Optimal perturbations depart from their homogeneous counterpart with large perturbation in the wake of the dipole associated with density effects.

000014575 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000014575 653__ $$a

000014575 7112_ $$a24th International Congress of Theoretical and Applied Mechanics$$cMontreal (CA)$$d2016-08-21 / 2016-08-26$$gICTAM2016
000014575 720__ $$aChomaz, Jean-Marc
000014575 8560_ $$ffischerc@itam.cas.cz
000014575 8564_ $$s195262$$uhttps://invenio.itam.cas.cz/record/14575/files/TS.FM07-3.06.pdf$$yOriginal version of the author's contribution as presented on CD,  page 945, code TS.FM07-3.06
.
000014575 962__ $$r13812
000014575 980__ $$aPAPER