On the flow over a rotationally oscillating flat plate: A numerical study
The characteristics of the flow in the wake of a plate that is normal to the free stream in its neutral position undergoing rotational oscillation has been investigated. The governing equations based on stream-function/vorticity formulation are solved numerically to determine the two-dimensional flo...
Gespeichert in:
Veröffentlicht in: | Journal of fluids and structures 2005-10, Vol.20 (7), p.961-974 |
---|---|
Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | The characteristics of the flow in the wake of a plate that is normal to the free stream in its neutral position undergoing rotational oscillation has been investigated. The governing equations based on stream-function/vorticity formulation are solved numerically to determine the two-dimensional flow field structure. The numerical simulations are performed in a rotating reference frame attached to the plate. The simulations focus on the lock-on phenomenon of vortex shedding for frequency ratios of forcing Strouhal number to natural shedding Strouhal number
St
e
/
St
n
=
0.96
–1.04 at a Reynolds number
Re
=
100
. The time histories of drag coefficient as well as surface vorticity of the plate show amplitude modulation when the vortex shedding is not-locked-on to the plate oscillation at smaller forcing amplitude. The modulation disappears once lock-on occurs where the vortex shedding is synchronized with the plate oscillation at larger amplitude. The limits of lock-on regime bounded by the forcing frequency and amplitude are found in good agreement with the experiments conducted at higher Reynolds numbers (
Re
=
3600
–
9800
). For the approach to lock-on from a lower frequency (
St
e
/
St
n
=
0.96
) and an upper frequency (
St
e
/
St
n
=
1.04
), the numerical simulations demonstrate significant differences in lock-on behavior, including the structure of vortices, fluctuation amplitudes of drag coefficient and surface vorticity, and route leading to lock-on. |
---|---|
ISSN: | 0889-9746 1095-8622 |
DOI: | 10.1016/j.jfluidstructs.2005.05.006 |