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Artikel
Feedback control of oscillatory thermocapillary convection in a half-zone liquid bridge’
| Författare: |
Shiomi, J., Kudo, M., Ueno, I., Kawamura, H., Amberg, G.A. |
| Dokumenttyp: |
Artikel |
| Tillstånd: |
Publicerad |
| Tidskrift: |
J. Fluid Mech. |
| Volym: |
496
193-211 |
| År: |
2003 |
AbstractActive feedback control was applied to suppress oscillations in thermocapillary convection in a half-zone liquid bridge. The experiment utilizes an unit aspect ratio liquid bridge where the most dangerous mode has an azimuthal wave number of 2 when the control is absent. Active control was realized by locally modifying the surface temperature using the local temperature measured at different locations fed back through a simple control law. The performance of control was quantified by analyzing local temperature signals and the flow structure was simultaneously identified by flow visualization. With optimal placement of sensors and heaters, proportional control can raise the critical Marangoni number by more than 40 percent. The amplitude of the oscillation can be suppressed to less than 30 percent of the initial value for a wide range of $\epsilon (< 0.9)$. The proportional control was tested for a period doubling state to stabilize the oscillation to a periodic state. Weakly nonlinear control was applied by adding a cubic term in the control law to improve the performance of the control and to alter the bifurcation characteristics of the system.
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