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Article
Control of thermocapillary instabilities far from threshold
| Authors: |
Brunet, P.B., Amberg, G.A., Alfredsson, P.H. |
| Document Type: |
Article |
| Pubstate: |
Published |
| Journal: |
Phys. Fluids |
| Volume: |
17
104109 |
| Year: |
2005 |
Abstract(With G. Amberg and P.H. Alfredsson). We report experiments on control of thermocapillary instabilities at high temperature differences, in an annular geometry. Previous studies (Phys. Fluids \textbf 3039-3045 (2002)) showed that a reasonable control of oscillatory instability could be achieved by optimizing a local heating feed-back process. We conducted experiments with a basic flow converging from periphery to center. This constitutes a more unstable configuration than previously, and enables appearance of higher-order instabilities and chaos. Applying successfully local feedback control to the periodic state close to the threshold, we extend the process to higher temperature differences, where non-linear as well as proportional/derivative control laws are necessary to obtain a significant decrease of the temperature fluctuations. Finally, proportional control allows us to synchronize a chaotic state, to a periodic one.
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