The onset of three-dimensional centrifugal global modes and their nonlinear development in a recirculating flow over a flat surface
Article dans une revue avec comité de lecture
Abstract
The three-dimensional stability dynamics of a separation bubble over a flat plate has been studied in both linear and nonlinear conditions. Using a global eigenvalue analysis, two centrifugal global modes are identified: an asymptotically unstable three-dimensional weakly growing mode which appears to be originated by a Rayleigh instability; a marginally stable three-dimensional steady mode which is originated by a convective Gortler instability. Direct numerical simulations show that both modes play a role in the route to transition toward the turbulent flow. A structural sensitivity analysis is used to investigate the mechanism of selection of the path toward transition when small perturbations are considered. Finally, a scenario of transition via Gortler modes breakdown is studied in detail, revealing the formation of trains of hairpin vortices in streamwise succession.
Files in this item
Collections
Related items
Showing items related by title, author, creator and subject.
-
Article dans une revue avec comité de lectureFARANO, Mirko; CHERUBINI, Stefania; DE PALMA, Pietro; ROBINET, Jean-Christophe (Springer Verlag, 2017)Bursts are recurrent, transient, highly energetic events characterized by localized variations of velocity and vorticity in turbulent wall-bounded flows. In this work, a nonlinear energy optimization strategy is employed ...
-
Article dans une revue avec comité de lecturePARENTE, ENZA; DE PALMA, Pietro; CHERUBINI, Stefania; ROBINET, Jean-Christophe (Cambridge University Press, 2022)Recently, many authors have investigated the origin and growth of turbulent bands in shear flows, highlighting the role of streaks and their inflectional instability in the process of band generation and sustainment. ...
-
Article dans une revue avec comité de lectureWe use direct numerical simulations in the presence of free-stream turbulence having different values of intensity, T u, and integral length scale, L, in order to determine which kind of structures are involved in the path ...
-
Article dans une revue avec comité de lectureCHERUBINI, Stefania; DE PALMA, Pietro; BOTTARO, Alessandro; ROBINET, Jean-Christophe (IOP Publishing, 2012)The understanding of transition in shear flows has recently progressed along new paradigms based on the central role of coherent flow structures and their nonlinear interactions. We follow such paradigms to identify, by ...
-
Article dans une revue avec comité de lectureCHERUBINI, Stefania; DE PALMA, Pietro; BOTTARO, Alessandro; ROBINET, Jean-Christophe (American Physical Society (APS), 2010)Recent studies have suggested that in some cases transition can be triggered by some purely nonlinear mechanisms. Here we aim at verifying such an hypothesis, looking for a localized perturbation able to lead a boundary-layer ...