• search hit 2 of 8
Back to Result List

Mean flow generation by Görtler vortices in a rotating annulus with librating side walls

  • Time periodic variation of the rotation rate of an annulus induces in supercritical regime an unstable Stokes boundary layer over the cylinder side walls, generating Görtler vortices in a portion of a libration cycle as a discrete event. Numerical results show that these vortices propagate into the fluid bulk and generate an azimuthal mean flow. Direct numerical simulations of the fluid flow in an annular container with librating outer (inner) cylinder side wall and Reynolds-averaged Navier–Stokes (RANS) equations as diagnostic equations are used to investigate generation mechanism of the retrograde (prograde) azimuthal mean flow in the bulk. First, we explain, phenomenologically, how absolute angular momentum of the bulk flow is mixed and changed due to the propagation of the Görtler vortices, causing a new vortex of basin size. Then we investigate the RANS equations for intermediate time scale of the development of the Görtler vortices and for long time scale of the order of several libration periods. The former exhibits signTime periodic variation of the rotation rate of an annulus induces in supercritical regime an unstable Stokes boundary layer over the cylinder side walls, generating Görtler vortices in a portion of a libration cycle as a discrete event. Numerical results show that these vortices propagate into the fluid bulk and generate an azimuthal mean flow. Direct numerical simulations of the fluid flow in an annular container with librating outer (inner) cylinder side wall and Reynolds-averaged Navier–Stokes (RANS) equations as diagnostic equations are used to investigate generation mechanism of the retrograde (prograde) azimuthal mean flow in the bulk. First, we explain, phenomenologically, how absolute angular momentum of the bulk flow is mixed and changed due to the propagation of the Görtler vortices, causing a new vortex of basin size. Then we investigate the RANS equations for intermediate time scale of the development of the Görtler vortices and for long time scale of the order of several libration periods. The former exhibits sign selection of the azimuthal mean flow. Investigating the latter, we predict that the azimuthal mean flow is proportional to the libration amplitude squared and to the inverse square root of the Ekman number and libration frequency and then confirms this using the numerical data. Additionally, presence of an upscale cascade of energy is shown, using the kinetic energy budget of fluctuating flow.show moreshow less

Export metadata

Additional Services

Search Google Scholar
Metadaten
Author: Abouzar Ghasemi, Marten KleinORCiD, Uwe HarlanderORCiD, Michael V. KurganskyORCiD, Eberhard Schaller, Andreas Will
DOI:https://doi.org/10.1063/1.4948406
Title of the source (English):Physics of Fluids
Document Type:Scientific journal article peer-reviewed
Language:English
Year of publication:2016
Contributing Corporation:University of Moscow
Tag:Centrifugal; Cylinder; Direct Numerical Simulation; Fluid Mechanics; Instability; Mean Flow; Mechanism; Rotation; Vortex
Volume/Year:28
Issue number:056603
First Page:1
Last Page:23
Faculty/Chair:Fakultät 2 Umwelt und Naturwissenschaften / FG Atmosphärische Prozesse
Fakultät 3 Maschinenbau, Elektro- und Energiesysteme / FG Aerodynamik und Strömungslehre
Einverstanden ✔
Diese Webseite verwendet technisch erforderliche Session-Cookies. Durch die weitere Nutzung der Webseite stimmen Sie diesem zu. Unsere Datenschutzerklärung finden Sie hier.