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On the lock-on of vortex shedding to oscillatory actuation around a circular cylinder
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10.1063/1.4772977
/content/aip/journal/pof2/25/1/10.1063/1.4772977
http://aip.metastore.ingenta.com/content/aip/journal/pof2/25/1/10.1063/1.4772977

Figures

Image of FIG. 1.
FIG. 1.

Computational setup for the present study. (a) Control setup for separated flow around a circular cylinder. (b) Computational domain setup with 5 different multi domains. The inner most domain (domain 1) is of size (, ) ∈ [−1, 3] × [−2, 2], and the largest one (domain 5) is [−31, 33] × [−32, 32]. Each domain has 200 × 200 cells.

Image of FIG. 2.
FIG. 2.

Steady and oscillatory momentum coefficients ( and ) for tangential non-zero-mean sinusoidal actuation (Eq. (4) ) with varied forcing amplitude .

Image of FIG. 3.
FIG. 3.

Representative cases with (left, / = 1.05) and without (right, / = 0.3) lock-on, for = 0.05. Shown on top are phase diagrams with ( , ) and on the bottom are the frequency contents of the drag coefficient time series.

Image of FIG. 4.
FIG. 4.

Time-average coefficient of drag ( ) shown for different forcing amplitudes over a range of actuation frequency ( / ). The dashed line (−− −) corresponds to the average baseline drag. Actuation is applied normal (left) and tangential (right) to the surface at the separation point (θ = 58°).

Image of FIG. 5.
FIG. 5.

Contour plots for the change in time-average drag ( ) resulting from normal and tangential forcing for varied actuation amplitude () and frequency ( / ). Actuators located at θ = 58°. Solid lines represent the boundaries between cases with (○) and without (•) lock-on.

Image of FIG. 6.
FIG. 6.

Contour plots of the flow without actuation and with normal sinusoidal actuation with Eq. (4) and = 0.50.

Image of FIG. 7.
FIG. 7.

Comparison of the time-average drag coefficient for different actuator positions on the cylinder. All cases are for tangential forcing and = 0.06, using Eq. (4) . Results for zero-average forcing with Eq. (8) is also shown.

Image of FIG. 8.
FIG. 8.

Different lock-on profiles observed for = 0.05 with non-zero-mean forcing, Eq. (4) . Cases (i)-(v) are described in text.

Image of FIG. 9.
FIG. 9.

Contour plots of flows with non-zero-mean tangential sinusoidal actuation and = 0.05 (Eq. (4) ). All cases are related to Fig. 8 .

Image of FIG. 10.
FIG. 10.

The left figure shows the reduction in for increasing actuator strength with steady blowing, Eq. (7) . The dashed line (−− −) corresponds to the average drag from the case without actuation. The right plot shows the corresponding maximum amplitude in the frequency spectrum for each amplitude.

Image of FIG. 11.
FIG. 11.

Contour plots of flows with steady tangential actuation for = 0.05 and 0.09 with Eq. (7) .

Image of FIG. 12.
FIG. 12.

The change in and lock-on characteristics for zero-mean tangential actuation. The left figure shows for different forcing amplitudes over a range of actuation frequency ( / ). The dashed line (−−−) corresponds to the average baseline drag. The right plot represents the corresponding lock-on characteristics with the change in shown by the counters for varied actuation amplitude () and frequency ( / ). Solid lines represent the boundaries between cases with (○) and without (•) lock-on.

Image of FIG. 13.
FIG. 13.

Time history of the drag coefficient for Cases (I)-(III) (see text) using non-zero-mean sinusoidal forcing with Eq. (4) and = 0.03. Shown by the dashed line (−−−) is the baseline average drag . Inserted contour plots represent the vorticity fields for Case (III).

Tables

Generic image for table
Table I.

Lift and drag coefficients and Strouhal number for flow over a circular cylinder at = 100.

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/content/aip/journal/pof2/25/1/10.1063/1.4772977
2013-01-02
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: On the lock-on of vortex shedding to oscillatory actuation around a circular cylinder
http://aip.metastore.ingenta.com/content/aip/journal/pof2/25/1/10.1063/1.4772977
10.1063/1.4772977
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