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186<br />
Boundary conditions and the effect of an electrical field<br />
gradient in the water dripping dynamics.<br />
J. C. Sartorelli a , T. N. Nogueira a , and J. S. Ribeiro a<br />
We have studied the effect of different nozzle shapes on the dynamics<br />
of water drop formation using two metallic nozzles with different levels. By<br />
keeping fixed the level of the water reservoir and having the faucet opening<br />
(S) as a control parameter we measured the time (Tn) between successive<br />
drops as well as their average volume 1 . For each nozzle, we have obtained<br />
regular, chaotic, and intermittent behaviors, boundary and interior crises.<br />
Comparing the two routes to chaos we have observed: a) for the same<br />
water flow (Φ) the reconstructed attractors Tn+1 vs. Tn are not necessarily<br />
the same and neither the dripping rate (f); b) At the crises, in spite of the<br />
sudden changes in the attractors shape and in the mean dripping rate, the<br />
water flow remained fixed because the average drops volume also<br />
changed; and c) for each nozzle we have observed hysteresis in the faucet<br />
opening/closing loop 2 .<br />
We have established an electrical field gradient in the region where the<br />
drop formation took place by assembling one of the nozzles inside a<br />
metallic cylindrical shell in which we applied an electrical voltage 3 (V) that<br />
was used as a second control parameter, while the metallic nozzle was<br />
kept grounded. This way, by keeping the faucet opening at a fixed position,<br />
the pendant water columns were polarized by the electrical field gradient<br />
that in turn was distorted by the column. The drops were ejected with net<br />
electrical charge proportional to the applied voltage. For V
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