Non-Linear Dynamics of a Flow-Focusing Bubble Generator: An Inverted Dripping Faucet

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Physical Review Letters [0031-9007] P. Garstecki, M.J. Fuerstman, G. M. Whitesides (2005) vol:94 iss:23 pg:234502[1]

Brief Summary

Figure 1: Schematic of the flow focusing device.
Figure 2: Different bubbling regimes for for various liquid flow rates (<math>Q</math>).

This letter deals with the chaotic behaviour of a microfluidic bubble generator (the device reported in [2]). Briefly, a gaseous thread is forced through a small orifice while being squeezed by an outer liquid flow; the thread then becomes energetically unstable which results in a bubble being pinched off. Upon varying various parameters of the system such as the gas pressure and liquid flow rate, several bifurcations in the bubble producing behaviour are observed. The deviced is pictured in micrographs in figures 1 and 2. Figure 2 shows different higher-order regimes of bubble production; the figure letter corresponds to the flow rates demarcated in figure 3. The study of the chaotic behaviour of these types of devices is crucial in order to implement them as emulsion makers, for colloid production and in droplet-based microfluidics among many other applications.

Figure 2: Different bubbling regimes for for various liquid flow rates (<math>Q</math>).

Capillarity Phenomena