Bubbles in fluids: an approach using chaos theory

Author(s)

Felipe Augusto Cardoso Pereira

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2013-05-13

Examining board members

Jose Carlos Sartorelli; Ibere Luiz Caldas; Thadeu Josino Pereira Penna; Alexandre Megiorin Roma; Rero Marques Rubinger

• Advisor: Jose Carlos Sartorelli; Eduardo Colli

Abstract

We studied the bubble formation dynamics in viscous fluids. We developed new experimental techniques to provide a better understanding of the system with one bubbling nozzle on the bottom of a cylinder filled with a water and glycerol solution. In this system, we control the air flow with a mass flowme- ter and a solenoid valve. We have measured simultaneously: the time between successive bubbles, using a laser focused in a photo-diode that has his light scattered when one bubble passes between them; the pressure waves that the bubbling causes in the air injecting system using microphones placed between the solenoid valve and the nozzle; and the geometry of the growing bubbles, through the analysis of the images collected by a high speed camera. The re- sults from this system motivated us to make a model for the bubbles formation dynamics that describes the period-adding route observed in the experiment and is based on first principles. We also investigated a new experimental system, that has two bubbling nozzles inside the same cylinder. We used the same experimetal techniques developed to the one nozzle experiment. We identified that the bubbling on the nozzles synchronizes due the coupling introduced by the liquid circulation, as the air injecting systems are independent. We studied the synchronization by constructing bifurcation diagrams and parameter spaces that show the syn- chronized regions. We also adapted the one nozzle bubbling model to decribe this system. We discovered that the interaction between the two bubble forma- tion dynamics is stronger when we increase the liquid height. (AU)