Experimental investigations on the bubble dynamics in a symmetric bifurcating channel

The flow of bubbles in a continuous liquid phase in a bifurcating microchannel is a commonly occurring phenomenon in micro-structured devices and physiological flows. Depending on the fluid properties, flow rates, and bifurcation geometry, different bubble dynamics can be observed at the bifurcation. In this work, the flow of bubbles in a continuous liquid stream is investigated experimentally in a Y-shaped bifurcating channel. Experiments are performed for three Newtonian liquids of different viscosities. For short bubbles and at low values of capillary numbers, bubbles remain unsplit and move to one of the daughter tubes. On a Ca-Re plane, long bubbles (lb > dm) are observed to split when Reynolds number (Re) is less than 20, whereas bubble splitting does not occur for higher value of Reynolds numbers. When the bubble splitting occurs, the mother bubble squeezes against the carina of the bifurcation, and a neck forms. The thinning of the neck with time is investigated for the three liquids.