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Flow separation control over a rounded ramp with spanwise alternating wall actuation.
- Source :
- Physics of Fluids; Jan2019, Vol. 31 Issue 1, pN.PAG-N.PAG, 22p, 2 Diagrams, 3 Charts, 16 Graphs
- Publication Year :
- 2019
-
Abstract
- An implicit large-eddy simulation is carried out to study turbulent boundary-layer separation from a backward-facing rounded ramp with active wall actuation control. This method, called spanwise alternating distributed strips control, is imposed onto the flat plate surface upstream of a rounded ramp by alternatively applying out-of-phase control and in-phase control to the wall-normal velocity component in the spanwise direction. As a result, the local turbulence intensity is alternatively suppressed and enhanced, leading to the creation of vertical shear-layers, which is responsible for the presence of large-scale streamwise vortices. These vortices exert a predominant influence on the suppression of the flow separation. The interaction between the large-scale vortices and the downstream recirculation zone and free shear-layer is studied by examining flow statistics. It is found that in comparison with the non-controlled case, the flow separation is delayed, the reattachment point is shifted upstream, and the length of the mean recirculation zone is reduced up to 8.49%. The optimal control case is achieved with narrow in-phase control strips. An in-depth analysis shows that the delay of the flow separation is attributed to the activation of the near-wall turbulence by the in-phase control strips and the improvement of the reattachment location is mainly due to the large-scale streamwise vortices, which enhance the momentum transport between the main flow and separated region. [ABSTRACT FROM AUTHOR]
- Subjects :
- TURBULENT boundary layer
WHIRLWINDS
SHEAR (Mechanics)
ACTUATORS
VELOCITY
Subjects
Details
- Language :
- English
- ISSN :
- 10706631
- Volume :
- 31
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Physics of Fluids
- Publication Type :
- Academic Journal
- Accession number :
- 134425391
- Full Text :
- https://doi.org/10.1063/1.5055948