Period Doubling in Bubbling from a Submerged Nozzle

Laura Grace

2016

A study was conducted of the period doubling route to chaos in rising bubbles. The impact of viscosity on the period doubling route was examined. To investigate this, a laser-photodiode system was used to detect nitrogen bubbles rising from a nozzle in the base of a jar. The liquid in the jar was a solution of water and glycerin. Concentrations of 0, 25, 50, 75, and 100% glycerin were used. The rising bubbles were detected by a photodiode as the laser beam was scattered by the bubble. From the start and end times where the bubble blocked and unblocked the laser, the period between successive bubbles and duration of each bubble was calculated in Igor Pro. The bubbling period was found to bifurcate for all solutions tested by increasing gas flow rates. The period bifurcated again in the range of flow rates tested for all solutions but pure glycerin due to the very high viscosity of pure glycerin compared to the other concentrations tested. This period doubling behavior indicates that the system may tend toward chaos for much higher flow rates. This supports the findings of previous experiments on transitions between bubbling stages in that the bubbling period doubles to chaotic jetting for high gas flow rates. First return maps show a trend toward a set of behaviors at high gas flow rates that my be worthy of future investigation.