Viviane S M Piassi | PubMed Health

PubMed2004

Bistability in bubble formation.

We obtain experimental data on time intervals of a bubble train generated from a nozzle with the air flow rate as the control parameter. Varying the length of the hose that connects the proportionating solenoid valve to the nozzle, we generate bifurcation diagrams showing period-adding cascades, among other dynamical phenomena. Then we construct a two-parameter family of one-dimensional maps whose bifurcation diagrams qualitatively match the experimental ones. The model indicates the existence of parameters where two attractors coexist, a phenomenon called bistability, and the same behavior is fully confirmed in the experiment.

Journal Article↗

PubMed2004

Period-adding bifurcations and chaos in a bubble column.

We obtained period-adding bifurcations in a bubble formation experiment. Using the air flow rate as the control parameter in this experiment, the bubble emission from the nozzle in a viscous fluid undergoes from single bubbling to a sequence of periodic bifurcations of k to k+1 periods, occasionally interspersed with some chaotic regions. Our main assumption is that this period-adding bifurcation in bubble formation depends on flow rate variations in the chamber under the nozzle. This assumption was experimentally tested by placing a tube between the air reservoir and the chamber under the nozzle in the bubble column experiment. By increasing the tube length, more period-adding bifurcations were observed. We associated two main types of bubble growth to the flow rate fluctuations inside the chamber for different bubbling regimes. We also studied the properties of piecewise nonlinear maps obtained from the experimental reconstructed attractors, and we concluded that this experiment is a spatially extended system.

Journal Article↗